Systemic Therapy

Patient Story

James was 68 when he learned his prostate cancer had spread to his bones. "You need hormone therapy," his oncologist said. James felt his stomach drop. He imagined losing everything that made him feel like himself — his energy, his strength, his desire. "Will I still be me?" he asked. His doctor paused and said, "You will still be you. But some things will change, and we are going to prepare you for every one of them." Over the next two years, James learned to manage hot flashes with a simple medication, kept his bones strong with exercise and a twice-yearly injection, and found that while his body changed, his spirit did not. His story is not unusual — and the tools to manage these changes are better than ever.

Part 1: What Is Systemic Therapy and Why Is It Needed?

When doctors talk about treating prostate cancer, they often divide treatments into two categories: local treatments (surgery and radiation) that target the prostate and surrounding area, and systemic treatments (medications) that work throughout the entire body.

Systemic therapy is needed when:

• Cancer has spread beyond the prostate (metastatic disease)
• Cancer is at high risk of spreading, even if it has not yet (combined with radiation for intermediate- and high-risk localized disease)
• Cancer has come back after local treatment (recurrence)
• Cancer continues to grow despite initial hormone treatment (castration-resistant disease)

The reason systemic therapy works in prostate cancer is rooted in a Nobel Prize-winning discovery from the 1940s. Doctors Charles Huggins and Clarence Hodges showed that prostate cancer depends on testosterone — the primary male hormone — to grow. Remove the testosterone, and the cancer slows or stops. This principle remains the foundation of prostate cancer treatment more than 80 years later.¹

Most testosterone (~95%) is produced in the testicles, with a small amount (~5%) made in the adrenal glands. Some prostate cancer cells can even produce their own testosterone. Modern systemic therapies target these sources at multiple levels.

📊 Illustration 12.1 — The testosterone pathway and where each drug blocks it

Part 2: Androgen Deprivation Therapy (ADT) — The Foundation

How ADT Works

The brain controls testosterone production through a chain of signals:

1. The hypothalamus (in the brain) releases GnRH (gonadotropin-releasing hormone)
2. GnRH tells the pituitary gland to release LH (luteinizing hormone) and FSH
3. LH tells the testicles to produce testosterone
4. Testosterone fuels prostate cancer growth

ADT interrupts this chain. The goal is to reduce testosterone to "castrate" levels — below 50 ng/dL (normal is 300–1000 ng/dL). At these low levels, most prostate cancer cells stop growing or die.²

Types of ADT

Surgical castration (bilateral orchiectomy)

This is the surgical removal of both testicles. It achieves immediate, permanent testosterone suppression — no ongoing injections or pills needed. It is equally effective as medical castration.² ³ Advantages include one-time cost, no medication adherence issues, and no testosterone flare. The main disadvantage is that it is irreversible and psychologically difficult for many men. Testicular prostheses are available for cosmetic purposes. Although rarely chosen in the United States today (fewer than 5% of men receiving ADT), it remains a valid and cost-effective option, especially in settings where medication access is limited.

LHRH agonists (the most common form of ADT)

These are injectable medications that initially stimulate, then suppress, testosterone production. They work by overwhelming the pituitary gland with constant GnRH stimulation until it stops responding — like a car alarm that eventually goes silent.

Common LHRH agonists include:

• Leuprolide (Lupron) — available as monthly, 3-month, 4-month, or 6-month injections
• Goserelin (Zoladex) — monthly or 3-month implant injected under the skin
• Triptorelin (Trelstar) — monthly, 3-month, or 6-month injections

Important: the testosterone flare. During the first 1–2 weeks of LHRH agonist treatment, testosterone levels temporarily rise before they fall. This "flare" can cause problems in men with bone metastases (worsening pain, spinal cord compression) or large prostate tumors (urinary obstruction). To prevent flare-related complications, a first-generation antiandrogen (such as bicalutamide) must be given for at least 7 days before and during the first weeks of LHRH agonist therapy when bone metastases are present.²

GnRH antagonists (no flare)

These medications directly block GnRH receptors in the pituitary gland, causing an immediate drop in testosterone without any flare.

• Degarelix (Firmagon) — monthly subcutaneous injection. Effective but causes injection-site reactions (pain, swelling, redness) in approximately 40% of patients.
• Relugolix (Orgovyx) — daily oral pill. The first oral GnRH antagonist approved for prostate cancer (2020).

The HERO trial (622 patients on relugolix, 308 on leuprolide) demonstrated that relugolix achieved superior testosterone suppression compared to leuprolide (96.7% vs. 88.8% maintained castration through 48 weeks). Relugolix also showed a 54% lower risk of major adverse cardiovascular events (2.9% vs. 6.2%; HR 0.46).⁴ Testosterone recovery after stopping relugolix was also faster — mean levels of 288 ng/dL at 90 days after discontinuation versus only 59 ng/dL with leuprolide.⁴

The REVELUTION trial (2026) provided a biological explanation for this cardiovascular difference: leuprolide was associated with significantly greater coronary artery plaque progression than relugolix, driven by an increase in noncalcified (less stable) plaque.⁵

First-generation antiandrogens

These medications block the androgen receptor directly, preventing testosterone from activating cancer growth. They are typically used in combination with LHRH agonists, not alone:

• Bicalutamide (Casodex) — most commonly used
• Flutamide (Eulexin)
• Nilutamide (Nilandron)

📊 Illustration 12.2 — Types of ADT comparison table

📊 Illustration 12.3 — LHRH agonist vs. antagonist: the flare concept

Part 3: When and How Long Is ADT Used?

The duration of ADT depends on the clinical situation:

With radiation for localized disease:

• Favorable intermediate risk: ADT is generally not recommended; if given, short-term (4–6 months)
• Unfavorable intermediate risk: short-term ADT (4–6 months)
• High/very-high risk: long-term ADT (18–36 months)
• High risk with combination EBRT + brachytherapy: shortened ADT (12 months) can be considered²

After surgery (adjuvant/salvage setting):

• With salvage radiation: 6–24 months
• For positive lymph nodes: variable duration

For biochemical recurrence without metastases:

• Intermittent ADT can be considered (see Part 4)
• Timing depends on PSA doubling time, patient anxiety, and comorbidities
• Patients who choose ADT monotherapy in the secondary treatment setting should consider intermittent ADT²

For metastatic disease:

• ADT is the backbone — but ADT alone is now discouraged for metastatic castration-sensitive disease unless there are clear contraindications to combination therapy²
• ADT should be combined with treatment intensification (an ARPI, with or without docetaxel — see Part 6)
• If ADT monotherapy is given, intermittent ADT can be considered to reduce toxicity²

📊 Illustration 12.4 — ADT duration by risk group

Part 4: Intermittent vs. Continuous ADT

What is intermittent ADT (iADT)?

Instead of staying on ADT continuously, treatment is cycled "on" and "off." ADT is started, and when PSA drops to a low level (typically ≤4 ng/mL), treatment is paused. When PSA rises again (typically ≥10–20 ng/mL), treatment is restarted. During "off" periods, testosterone partially recovers, and many side effects improve.

What does the evidence show?

A systematic review of 9 randomized trials with 5,508 patients found no significant difference in overall survival between intermittent and continuous ADT (pooled HR 1.02; 95% CI 0.94–1.11) for men with relapsing, locally advanced, or metastatic disease.⁶ Quality of life was better with intermittent ADT — particularly sexual function, physical activity, and general well-being — and medication costs were reduced by approximately 48%.⁶

For metastatic disease specifically, the evidence is less clear. The SWOG 9346 trial (1,535 patients) could not confirm that intermittent ADT was non-inferior to continuous ADT — median survival was 5.1 years with intermittent therapy versus 5.8 years with continuous therapy, and a 20% increase in the risk of death could not be ruled out.⁷

Bottom line: Intermittent ADT is a reasonable option for men with biochemical recurrence (non-metastatic disease), where it offers quality-of-life benefits without compromising survival. For metastatic disease, continuous ADT (or ADT combined with treatment intensification) is generally preferred.

📊 Illustration 12.5 — Intermittent ADT: the on/off cycle explained visually

Part 5: Side Effects of ADT — The Full Picture

This may be the most important section of this chapter. ADT affects nearly every system in the body because testosterone plays a role in many functions beyond the prostate — including bone strength, heart health, metabolism, mood, and sexual function. Understanding these side effects — and knowing they can be managed — is essential.

A. Hot Flashes (Vasomotor Symptoms)

Hot flashes are one of the most common and bothersome side effects of ADT, affecting up to 60% of men.⁸ They can be severe, disruptive to sleep, and significantly impact quality of life.

Management options include:

Non-hormonal medications (preferred first-line):

• Venlafaxine (37.5–75 mg daily) — an antidepressant that reduces hot flashes by approximately 10–25%. It is one of the most studied agents in men on ADT, though data in males are more limited than in women.⁹ ¹⁰
• Gabapentin (300 mg three times daily, preferred anticonvulsant) — reduces hot flashes by approximately 10–20%. Start at a low dose and increase as tolerated. Causes drowsiness, so it is often best taken at bedtime, where it may also improve sleep.⁹ ¹⁰
• Oxybutynin (2.5–5 mg twice daily) — an anticholinergic medication typically used for overactive bladder. The Alliance A222001 trial (2026) specifically studied oxybutynin in men with prostate cancer on ADT and found it superior to placebo, with a dose-dependent reduction in hot flashes: men on 5 mg twice daily had an average reduction of 6.89 hot flashes per day compared to 2.15 with placebo (P .001). No grade 3 or higher side effects occurred. Side effects include dry mouth and constipation.¹¹
• Neurokinin receptor antagonists — elinzanetant (120 mg daily, preferred) and fezolinetant (45 mg daily) are FDA-approved for menopausal hot flashes in women and are listed in the NCCN Survivorship Guidelines as options. They target the brain's thermoregulatory center directly. Liver function monitoring is required. These have not been specifically tested in men on ADT in large trials, but the mechanism is the same.⁹ ¹⁰

Hormonal options (in appropriate candidates):

• Medroxyprogesterone — effective but carries hormonal risks; requires specialist referral.⁹

Non-pharmacologic approaches:

• Acupuncture, cognitive behavioral therapy (CBT), exercise, weight loss, and lifestyle modifications (avoiding alcohol triggers, layered clothing, cool environments).⁹

📊 Illustration 12.6 — ADT side effects: the body map

B. Sexual Dysfunction

ADT causes near-universal loss of libido and erectile dysfunction in more than 70% of men. Nocturnal and morning erections are lost. Penile and testicular size may decrease over time. PDE5 inhibitors (such as sildenafil or tadalafil) may help some men maintain erections, but they cannot restore libido. This topic is covered in detail in Chapter 15 (Survivorship).⁸

C. Body Composition Changes

ADT increases body fat by approximately 9% and decreases muscle mass (sarcopenia). Weight gain is common. The single most important intervention is resistance and aerobic exercise — this is not optional; it is a critical part of treatment. Studies consistently show that structured exercise programs reduce fat gain, preserve muscle, improve fatigue, and enhance quality of life in men on ADT.⁸

D. Bone Health

ADT significantly increases the risk of osteoporosis and fractures. A large meta-analysis found ADT was associated with a 59% increased risk of bone fractures (HR 1.59) and a 173% increased risk of osteoporosis (HR 2.73).⁸

Prevention and management:

• Baseline DEXA scan for patients at increased fracture risk; FRAX score assessment
• Calcium (1,000–1,200 mg/day from diet and supplements) and vitamin D3 (target blood level 30–50 ng/mL)
• Pharmacologic options for osteoporosis prevention:
• Denosumab (Prolia) 60 mg subcutaneous injection every 6 months
• Zoledronic acid 5 mg IV once yearly
• Alendronate 70 mg oral weekly
• Important: Stopping denosumab can cause rebound bone loss and vertebral fractures — patients must transition to a bisphosphonate before discontinuing denosumab.¹²
• Note: These are osteoporosis-prevention doses. Patients with bone metastases receive different, higher doses (see Part 11).

E. Cardiovascular and Metabolic Effects

ADT increases the risk of diabetes, coronary heart disease, and metabolic syndrome. The cardiovascular risk may be highest in the first 6 months of treatment.⁸

GnRH antagonists (relugolix, degarelix) may have a lower cardiovascular risk than LHRH agonists. The HERO trial showed a 54% lower rate of major cardiovascular events with relugolix compared to leuprolide.⁴ The REVELUTION trial (2026) provided a biological explanation: leuprolide was associated with significantly greater coronary artery plaque progression, driven by noncalcified (less stable) plaque.⁵

Cardiovascular prevention — the ABCDEs:

• Aspirin/Anticoagulation (if indicated)
• Blood pressure control
• Cholesterol management
• Diabetes screening and Diet
• Exercise

Cardio-oncology referral should be considered for patients at elevated cardiovascular risk.

F. Cognitive and Emotional Effects

Depression, mood swings, fatigue, and sleep disturbance are common. Cognitive dysfunction has been reported but remains controversial. Fatigue is one of the most frequent complaints and often improves with exercise.⁸

G. Gynecomastia (Breast Enlargement)

Breast tissue growth occurs in approximately 10% of men on ADT, and is more common with antiandrogens such as bicalutamide (up to 70% with bicalutamide monotherapy).⁸

Prevention and treatment:

• Prophylactic breast radiation (a single dose of 10 Gy or two doses of 6 Gy) — must be delivered BEFORE breast tissue develops. Once tissue has grown, radiation is less effective.⁹
• Tamoxifen — the most effective medical treatment for established gynecomastia.⁹
• Reduction mammoplasty — surgical option for severe cases.

H. Other Effects

• Anemia (decreased red blood cell production)
• Body hair thinning (some bald men may notice scalp hair regrowth)
• Venous thromboembolism
• QT prolongation on ECG (monitor with certain medications)
• Joint and muscle pain

📊 Illustration 12.7 — Managing ADT side effects: practical strategies table

Part 6: Next-Generation Hormonal Agents (ARPIs)

Traditional ADT reduces testosterone production, but cancer cells can still find ways to use tiny amounts of remaining androgens. Androgen Receptor Pathway Inhibitors (ARPIs) are more powerful drugs that either block the androgen receptor more completely or shut down androgen production at additional sites (including within the tumor itself).

A. Abiraterone (Zytiga)

Abiraterone blocks an enzyme called CYP17A1, which is needed to produce androgens in the adrenal glands, testes, and within the tumor itself. It must be taken with a low-dose steroid (prednisone or methylprednisolone) to prevent side effects from cortisol disruption.

• Standard dose: 1,000 mg daily on an empty stomach (no food for 2 hours before or 1 hour after)
• Fine-particle formulation: 500 mg daily, can be taken without regard to food
• Low-cost alternative: 250 mg daily taken with a low-fat breakfast (shown to achieve similar drug levels at a fraction of the cost)
• Side effects: fluid retention, high blood pressure, low potassium, liver toxicity (requires monitoring), fatigue.¹³

B. Enzalutamide (Xtandi)

Enzalutamide blocks the androgen receptor directly — it prevents testosterone from entering the cell nucleus and activating cancer growth genes.

• Dose: 160 mg daily, with or without food
• Side effects: fatigue (the most common), seizure risk (rare, 1%), falls and fractures, cognitive effects ("brain fog"), high blood pressure.¹⁴

C. Apalutamide (Erleada)

Similar mechanism to enzalutamide.

• Dose: 240 mg daily
• Side effects: skin rash (common, ~24%), fatigue, falls and fractures, thyroid dysfunction (check thyroid levels).¹⁵

D. Darolutamide (Nubeqa)

Similar mechanism but may cross the blood-brain barrier less than enzalutamide or apalutamide, potentially causing fewer central nervous system side effects (fatigue, cognitive changes, seizures).

• Dose: 600 mg twice daily with food
• Side effects: fatigue, pain in extremities; generally the best-tolerated ARPI.¹⁶

When Are ARPIs Used?

ARPIs have transformed prostate cancer treatment and are now used across multiple disease states:

• Metastatic castration-sensitive disease (mCSPC): ADT + ARPI is the standard of care. ADT alone is now discouraged. Options include abiraterone, enzalutamide, apalutamide, or darolutamide (with or without docetaxel).¹³ ¹⁷
• Non-metastatic castration-resistant disease (nmCRPC): Enzalutamide, apalutamide, or darolutamide added to ADT.¹⁴ ¹⁵ ¹⁶
• Metastatic castration-resistant disease (mCRPC): Abiraterone or enzalutamide as first-line; also used in combination with PARP inhibitors for patients with specific mutations.¹³ ¹⁴
• High-risk biochemical recurrence: Enzalutamide or apalutamide with ADT.¹⁴ ¹⁵

Important: Cross-resistance exists between ARPIs. Switching from one ARPI to another (for example, from abiraterone to enzalutamide) generally provides limited benefit. This is why the NCCN recommends docetaxel as the preferred next step after an ARPI fails, rather than switching to a different ARPI.¹⁸

📊 Illustration 12.8 — ARPI comparison table

Part 7: Chemotherapy

Chemotherapy uses drugs that kill rapidly dividing cells. Unlike hormone therapy, which starves the cancer of testosterone, chemotherapy directly damages the cancer cell's ability to divide and grow.

A. Docetaxel (Taxotere)

Docetaxel was the first chemotherapy to show a survival benefit in metastatic castration-resistant prostate cancer (2004). It works by disrupting microtubules — the internal scaffolding that cells need to divide.

• For mCRPC: Given IV every 3 weeks with a steroid (prednisone or dexamethasone), typically for up to 10 cycles. It improved median survival by approximately 2–3 months compared to the previous standard (mitoxantrone).¹⁸ ¹⁹
• For metastatic castration-sensitive disease (mCSPC): The CHAARTED and STAMPEDE trials showed that adding 6 cycles of docetaxel to ADT improved survival by 10–14 months, with the greatest benefit in men with high-volume disease. An individual patient data meta-analysis of 2,261 patients confirmed a clear survival benefit (HR 0.79; P .0001), representing a 5-year absolute improvement of approximately 9–11%.²⁰ ²¹
• Triplet therapy: Docetaxel is now also used in combination with ADT + an ARPI (such as darolutamide) for high-volume mCSPC, based on the ARASENS trial.¹⁶
• Side effects: fatigue, nausea, hair loss, peripheral neuropathy (numbness/tingling in hands and feet), low blood counts (neutropenia), infection risk, fluid retention, nail changes. Growth factor support (G-CSF) may be needed to prevent dangerous drops in white blood cells.¹⁸

B. Cabazitaxel (Jevtana)

Cabazitaxel is a second-generation taxane designed to work even when cancer cells have become resistant to docetaxel.

• For mCRPC after docetaxel: The TROPIC trial showed cabazitaxel improved survival compared to mitoxantrone. The CARD trial demonstrated that cabazitaxel was superior to switching to another ARPI in patients who had already received docetaxel and one ARPI — improving radiographic progression-free survival and reducing the risk of death.¹⁸ ²²
• Dose: 20 or 25 mg/m² IV every 3 weeks. The 20 mg/m² dose has less toxicity with similar efficacy.¹⁸
• Side effects: similar to docetaxel but with less neuropathy and more neutropenia. Growth factor support is often needed.
• Cost consideration: Cabazitaxel remains under patent and costs approximately $54,000 for a 6-cycle course, compared to approximately $85 for generic docetaxel.²²

C. Cabazitaxel + Carboplatin

For aggressive variant mCRPC — defined by visceral metastases, low PSA with bulky disease, high LDH, neuroendocrine features, or unfavorable genomics (defects in at least 2 of PTEN, TP53, and RB1). This combination requires growth factor support and is reserved for fit patients.¹⁸

D. Mitoxantrone

Mitoxantrone with prednisone may provide symptom relief (palliation) but has NOT been shown to extend survival. It is reserved for patients who cannot tolerate other therapies.¹⁸

📊 Illustration 12.9 — Chemotherapy: what to expect

Part 8: Immunotherapy

A. Sipuleucel-T (Provenge)

Sipuleucel-T holds a special place in cancer history — it was the first FDA-approved immunotherapy for any cancer (2010).²³

How it works: Sipuleucel-T is made from your own immune cells. The process involves three steps, repeated three times over about one month:

1. Leukapheresis: Your blood is drawn through a special machine that collects white blood cells (similar to donating blood, but takes 3–4 hours).
2. Laboratory processing: Your cells are sent to a manufacturing facility where they are "trained" to recognize a protein found on prostate cancer cells (prostatic acid phosphatase, or PAP).
3. Infusion: The activated cells are infused back into your bloodstream through an IV, where they seek out and attack cancer cells.

The IMPACT trial (512 patients) showed that sipuleucel-T reduced the risk of death by 22% compared to placebo. Median survival improved by 4.1 months (25.8 months vs. 21.7 months; HR 0.78; P = 0.03). The 3-year survival rate was 31.7% versus 23.0%.²³ ²⁴

Important points:

• Sipuleucel-T is only for asymptomatic or minimally symptomatic mCRPC patients with no liver metastases, life expectancy greater than 6 months, and good performance status (ECOG 0–1).²⁵
• It does NOT lower PSA — this confuses many patients and even some doctors. The benefit is in survival, not PSA response. Do not stop treatment because PSA does not drop.²³ ²⁴
• Patients with lower baseline PSA levels (≤22.1 ng/mL) appeared to benefit most, with a 13-month improvement in survival.²⁶
• Side effects are generally mild: chills, fever, and headache related to immune activation, usually resolving within 1–2 days.²³
• Sipuleucel-T is approved in the United States but is not available in Europe.²⁷

B. Pembrolizumab (Keytruda)

Pembrolizumab is a checkpoint inhibitor — it "releases the brakes" on the immune system, allowing T cells to attack cancer cells more effectively.

• Only for the small subset (~3–5%) of mCRPC patients whose tumors are MSI-High (MSI-H) or dMMR (deficient mismatch repair). This is determined by genetic testing of the tumor.²⁵
• Prostate cancer is generally an immunologically "cold" tumor — most patients do not respond to checkpoint inhibitors. The KEYNOTE-641 trial showed no benefit from adding pembrolizumab to enzalutamide in unselected mCRPC patients.²⁷
• Side effects can be serious: immune-mediated pneumonitis, colitis, hepatitis, endocrine disorders (thyroid, adrenal, pituitary), skin reactions, and kidney inflammation. These require close monitoring and sometimes urgent treatment with steroids.²⁵

📊 Illustration 12.10 — How sipuleucel-T works

Part 9: Targeted Therapy — PARP Inhibitors

PARP inhibitors represent a new era of precision medicine in prostate cancer — treatments chosen based on the specific genetic makeup of your tumor.

How They Work

Every cell in your body has systems to repair damaged DNA. One important repair system is called homologous recombination repair (HRR). Genes like BRCA1, BRCA2, ATM, and others are essential for this system to work.

When a cancer cell has a mutation in one of these HRR genes, its DNA repair is already weakened. PARP is another DNA repair enzyme that serves as a "backup" system. PARP inhibitors block this backup, leaving the cancer cell with no way to fix its DNA — leading to cell death. Think of it as "kicking them while they're down."²⁸

Normal cells still have one working copy of the HRR gene, so they can survive. This is why PARP inhibitors preferentially kill cancer cells with HRR mutations while sparing normal tissue.

Who Benefits?

Approximately 20% of men with metastatic prostate cancer have alterations in DNA repair genes. The response to PARP inhibitors follows a clear hierarchy:²⁸ ²⁹

• BRCA2 mutations: Best responses — the strongest evidence of benefit
• BRCA1 mutations: Good responses
• ATM and other HRR gene mutations: Variable and generally less robust responses

FDA-Approved PARP Inhibitors for Prostate Cancer

The NCCN Guidelines list the following approved options:²⁸

• Olaparib (Lynparza) — for mCRPC with HRR gene mutations after prior ARPI (PROfound trial: improved survival by 4.4 months despite 67% crossover)²⁹
• Rucaparib (Rubraca) — for mCRPC with BRCA mutations after prior ARPI and taxane (TRITON2 trial)²⁸
• Olaparib + abiraterone — for mCRPC with BRCA mutations (PROpel trial)²⁸
• Talazoparib + enzalutamide (Talzenna + Xtandi) — for mCRPC with HRR mutations (TALAPRO-2 trial: improved radiographic progression-free survival; HR 0.63)³⁰
• Niraparib + abiraterone (Akeega) — for mCRPC with BRCA mutations (MAGNITUDE trial)²⁸

ASCO guidelines recommend HRR testing prior to initiation of systemic therapy for mCRPC. For patients with BRCA1/2 alterations, preferred first-line options include niraparib + abiraterone, olaparib + abiraterone, or talazoparib + enzalutamide.³¹

Side effects of PARP inhibitors: fatigue, nausea, anemia (may require transfusions), low platelets, low white blood cells. Regular blood count monitoring is essential.²⁸

The key message: Genetic testing (both germline and somatic/tumor) is recommended for all patients with metastatic or castration-resistant prostate cancer. If you have not been tested, ask your doctor.²⁸

📊 Illustration 12.11 — PARP inhibitor table

Part 10: Radiopharmaceuticals — Radioactive Medicines

Radiopharmaceuticals are a unique category of treatment — they are radioactive drugs injected into the bloodstream that seek out and destroy cancer cells from the inside. Unlike external radiation therapy (which aims beams at the body from outside), these drugs travel through the blood and deliver radiation directly to cancer cells wherever they are.

A. Radium-223 (Xofigo)

Radium-223 is a radioactive form of radium that mimics calcium. Because bone metastases from prostate cancer are "osteoblastic" (they stimulate new bone formation), radium-223 is naturally attracted to these areas of rapid bone turnover. Once there, it emits alpha particles — tiny, powerful bursts of radiation that kill nearby cancer cells while causing minimal damage to surrounding tissue (alpha particles travel less than 100 micrometers, or about 10 cell diameters).³²

The ALSYMPCA trial showed that radium-223 improved overall survival by 3.6 months compared to placebo in men with symptomatic bone-predominant mCRPC (median OS 14.9 vs. 11.3 months; HR 0.70; P .001).³²

The PEACE-3 trial (2025–2026) demonstrated that combining radium-223 with enzalutamide significantly improved both radiographic progression-free survival (19.4 vs. 16.4 months; HR 0.69) and overall survival (median 38.2 vs. 32.6 months; HR 0.76; P = 0.0096) as first-line therapy for mCRPC with bone metastases. This represents a ~6-month survival advantage for the combination.³³ ³⁴

Key points:

• Given IV once monthly for 6 months.³²
• Only for patients with bone-predominant metastases and NO visceral metastases (no liver, lung, or brain spread).³²
• Must be used with a bone-protective agent (denosumab or zoledronic acid) — the ERA-223 trial showed increased fractures when radium-223 was combined with abiraterone without bone protection.³²
• Side effects: nausea, diarrhea, low blood counts, bone pain flare (temporary worsening before improvement).

B. Lutetium-177 PSMA-617 (Pluvicto)

Lu-177 PSMA-617 represents the cutting edge of prostate cancer treatment — a concept called "theranostics" (therapy + diagnostics). The same molecule (PSMA) used to find cancer on a PET scan is used to deliver radiation treatment directly to cancer cells.

How it works: PSMA (prostate-specific membrane antigen) is a protein found on the surface of most prostate cancer cells. Lu-177 PSMA-617 is a radioactive molecule that binds to PSMA, delivering beta-particle radiation directly to cancer cells and the surrounding tumor microenvironment.³⁵

The VISION trial (831 patients) showed that adding Lu-177 PSMA-617 to standard of care improved overall survival by 4 months (15.3 vs. 11.3 months; HR 0.62; P .001) in men with PSMA-positive mCRPC who had received at least one ARPI and one or two taxanes.³⁵ ³⁶

The PSMAfore trial (468 patients) extended the evidence to the pre-chemotherapy setting: Lu-177 PSMA-617 significantly prolonged radiographic progression-free survival compared to switching ARPIs (11.6 vs. 5.6 months; HR 0.49) in taxane-naive patients. Quality of life was better preserved, and symptomatic skeletal events were delayed.³⁷ ³⁸

Key points:

• Given IV every 6 weeks for up to 6 treatments (7.4 GBq per dose).³²
• Requires a PSMA PET scan to confirm PSMA-positive disease before treatment. Not for patients with dominant PSMA-negative lesions.³²
• FDA-approved for mCRPC after ARPI therapy, in patients who have received prior taxane or are appropriate to delay taxane.³⁵
• Side effects: dry mouth (the salivary glands express PSMA), nausea, fatigue, low blood counts (especially lymphocytes and platelets).³⁵ ³⁶
• Radiation safety precautions are required after each treatment — patients emit low levels of radiation for several days and must follow specific guidelines to protect family members.³²

📊 Illustration 12.12 — How radiopharmaceuticals work

Part 11: Bone-Protective Agents (for Metastatic Disease)

This section is separate from the osteoporosis prevention discussed in Part 5D. Here, we are talking about patients who already have bone metastases — the goal is to prevent skeletal complications such as fractures, spinal cord compression, and the need for bone surgery or radiation.

Two options:

• Denosumab (Xgeva) 120 mg subcutaneous injection monthly — a higher dose than the osteoporosis-prevention formulation (Prolia 60 mg every 6 months).³⁹
• Zoledronic acid (Zometa) 4 mg IV every 3–4 weeks — also a higher dose and more frequent schedule than the osteoporosis dose.³⁹

Both require:

• Calcium and vitamin D supplementation
• Dental evaluation before starting — risk of osteonecrosis of the jaw (ONJ), a rare but serious condition where the jawbone does not heal properly. Good dental hygiene and avoiding invasive dental procedures during treatment reduce this risk.
• Monitoring for hypocalcemia (low calcium levels)

📊 Illustration 12.13 — Bone protection: two different situations, two different doses

Part 12: What to Expect at Your First ADT Injection

Many men are anxious about their first hormone therapy injection. Here is what to expect:

Before the appointment:

• Your doctor will have discussed the type of ADT (LHRH agonist vs. antagonist) and the injection schedule
• If you have bone metastases and are starting an LHRH agonist, you will likely start an antiandrogen pill (such as bicalutamide) at least 7 days before the injection to prevent testosterone flare
• If you are starting relugolix (oral), you will take a loading dose of 3 tablets on day 1, then 1 tablet daily

At the appointment:

• The injection is given subcutaneously (under the skin) or intramuscularly (into the muscle), depending on the medication
• The injection itself takes only a few seconds
• Some formulations (such as leuprolide depot) use a slightly larger needle because the medication is thick
• Degarelix injections may cause a stinging or burning sensation at the injection site

After the injection:

• You may feel mild soreness at the injection site for 1–2 days
• Hot flashes may begin within 1–2 weeks (sometimes sooner with antagonists)
• Your doctor will check your testosterone level (usually at 1 month) to confirm it has dropped to castrate levels (50 ng/dL)
• If testosterone does not suppress adequately, your doctor may switch medications or add an antiandrogen

Ongoing monitoring:

• Testosterone levels should be checked periodically to ensure adequate suppression
• PSA should be monitored regularly (the schedule depends on your disease state)
• Baseline and periodic assessments: DEXA scan, cardiovascular risk factors, blood glucose, lipid panel, CBC

Part 13: Treatment Sequencing — The Big Picture

The landscape of systemic therapy for prostate cancer is complex and constantly evolving. One of the most important concepts to understand is that what you received first affects what works next.

Key principles:

• Cross-resistance between ARPIs limits the benefit of switching from one ARPI to another. For example, if cancer progresses on enzalutamide, switching to abiraterone generally provides limited benefit. This is why the NCCN recommends docetaxel as the preferred next step after ARPI failure, rather than a second ARPI.¹⁸
• The CARD trial confirmed this: cabazitaxel was superior to switching ARPIs in patients who had already received docetaxel and one ARPI.²²
• Genetic testing guides therapy selection: BRCA mutations → PARP inhibitors; MSI-H/dMMR → pembrolizumab; PSMA-positive → Lu-177 PSMA-617.²⁸ ³²
• Real-world data show that only about 54% of mCRPC patients receive second-line therapy, and attrition rises significantly with each subsequent line. This underscores the importance of choosing the right first-line treatment.
• Palliative care should be integrated early — not just at end of life. Palliative care teams help manage symptoms, side effects, and quality of life throughout the treatment journey.

📊 Illustration 12.14 — Treatment sequencing flowchart

Part 14: Research Frontiers

The future of systemic therapy for prostate cancer is exciting. Here are some of the most promising areas of research:

• Bipolar androgen therapy (BAT): An investigational approach that cycles between high and low testosterone levels. The theory is that rapidly flooding cancer cells with testosterone after a period of deprivation can cause them to die. Early trials show promising results in select patients.
• AR degraders: Next-generation drugs that do not just block the androgen receptor — they destroy it entirely. These may overcome resistance to current ARPIs.
• Antibody-drug conjugates (ADCs): Targeted delivery of chemotherapy directly to cancer cells using antibodies as "guided missiles."
• Bispecific T-cell engagers: Molecules that physically connect immune cells (T cells) to cancer cells, forcing the immune system to attack.
• CAR-T cell therapy: Engineering a patient's own immune cells to recognize and attack prostate cancer. Still early in development for prostate cancer.
• New radiopharmaceuticals: Actinium-225 PSMA (an alpha-emitting version of Lu-177 PSMA-617 with potentially greater potency), combination radioligand strategies (the AlphaBet trial is testing Lu-177 PSMA + radium-223 together).⁴⁰
• Combination immunotherapy: Sipuleucel-T combined with checkpoint inhibitors, BAT, or radiation to convert prostate cancer from an immunologically "cold" to "hot" tumor.⁴¹
• Liquid biopsy: Using blood tests to detect circulating tumor DNA for real-time treatment monitoring and early detection of resistance.

Myth vs. Fact

Myth: "Hormone therapy will turn me into a woman."

Fact: ADT reduces testosterone but does not feminize you. You remain male. Some body changes occur (less body hair, possible breast tenderness, changes in fat distribution), but these are manageable and do not change who you are.

Myth: "Chemotherapy is always a last resort."

Fact: Docetaxel is now used early — in combination with ADT and ARPIs — for metastatic castration-sensitive disease. Starting chemotherapy early, when you are stronger, often leads to better outcomes than waiting until the cancer is resistant to hormones.²⁰ ²¹

Myth: "If my PSA doesn't drop, the treatment isn't working."

Fact: Sipuleucel-T improves survival by 4.1 months without lowering PSA. PSA is an important marker, but it is not the only measure of treatment success. Some treatments work by slowing cancer growth or activating the immune system in ways that PSA does not capture.²³ ²⁴

Myth: "Once I start hormone therapy, I can never stop."

Fact: Intermittent ADT — cycling treatment on and off — is a valid option for men with biochemical recurrence. During "off" periods, testosterone partially recovers, and many side effects improve. Multiple trials show no survival difference compared to continuous ADT in the non-metastatic setting.⁶

Myth: "PARP inhibitors work for everyone with prostate cancer."

Fact: PARP inhibitors work best for patients with specific genetic mutations, especially BRCA2. Only about 20% of men with metastatic prostate cancer carry these mutations. Genetic testing is essential to determine eligibility.²⁸ ²⁹

Myth: "Radium-223 and Pluvicto are the same thing."

Fact: They are very different. Radium-223 targets bone (it mimics calcium and goes to areas of bone turnover). Lu-177 PSMA-617 (Pluvicto) targets PSMA protein on cancer cells anywhere in the body. They are used in different clinical situations and have different eligibility requirements.³² ³⁵

Myth: "ADT side effects are inevitable and untreatable."

Fact: While ADT does cause side effects, most can be prevented or significantly reduced with proactive strategies — exercise, bone-protective agents, cardiovascular monitoring, medications for hot flashes, and psychological support. The key is planning ahead, not reacting after problems develop.⁸ ⁹

Myth: "If the cancer becomes castration-resistant, there is nothing left to do."

Fact: Castration-resistant does not mean treatment-resistant. There are now more than a dozen FDA-approved treatments for castration-resistant prostate cancer, including next-generation hormonal agents, chemotherapy, immunotherapy, PARP inhibitors, and radiopharmaceuticals. Many men live years with well-managed castration-resistant disease.¹⁸

Questions to Ask Your Doctor

About hormone therapy:

1. Why do I need systemic therapy? What is the goal — cure, long-term control, or symptom relief?
2. Which type of ADT do you recommend (LHRH agonist, GnRH antagonist, or orchiectomy) and why?
3. Should I receive a GnRH antagonist (relugolix or degarelix) instead of an LHRH agonist, especially given my cardiovascular history?
4. How long will I be on hormone therapy?
5. Is intermittent ADT an option for me?
6. Do I need a next-generation hormonal agent (ARPI) in addition to ADT?

About side effects and monitoring:

1. What side effects should I expect, and how can we prevent or manage them before they start?
2. Should I have a DEXA scan and cardiovascular risk assessment before starting ADT?
3. Should I see a cardiologist or endocrinologist while on ADT?
4. What exercise program do you recommend while I am on treatment?
5. How often will you check my testosterone level to make sure it is adequately suppressed?

About advanced treatments:

1. Has my tumor been tested for genetic mutations (BRCA, MSI-H, HRR genes)?
2. Am I a candidate for immunotherapy, PARP inhibitors, or radiopharmaceuticals?
3. Is a PSMA PET scan appropriate for me?
4. What is the plan if this treatment stops working? What comes next?

About the big picture:

1. Are there clinical trials I should consider?
2. What can I do to stay as healthy as possible while on treatment — diet, exercise, bone health, heart health?
3. Should I be referred to a palliative care team for symptom management and quality of life support?

Key Takeaways

• Androgen deprivation therapy (ADT) is the foundation of systemic treatment for prostate cancer. It works by reducing testosterone to starve the cancer. ADT can be achieved surgically (orchiectomy) or medically (LHRH agonists or GnRH antagonists).
• GnRH antagonists (relugolix, degarelix) avoid the testosterone flare seen with LHRH agonists and may carry a lower cardiovascular risk. The HERO trial showed relugolix had 54% fewer major cardiovascular events than leuprolide.⁴
• ADT has significant side effects affecting bones, heart, metabolism, sexual function, mood, and body composition — but most can be prevented or managed with proactive strategies including exercise, bone-protective agents, and cardiovascular monitoring.⁸ ⁹
• Next-generation hormonal agents (ARPIs) — abiraterone, enzalutamide, apalutamide, darolutamide — are now standard in combination with ADT for metastatic disease. ADT alone is discouraged for metastatic castration-sensitive prostate cancer.¹³ ¹⁷
• Chemotherapy (docetaxel, cabazitaxel) has proven survival benefits and is increasingly used early in combination with ADT and ARPIs for metastatic disease.²⁰ ²¹
• Sipuleucel-T was the first FDA-approved cancer immunotherapy. It improves survival without lowering PSA — do not judge its effectiveness by PSA alone.²³ ²⁴
• PARP inhibitors are targeted therapies for patients with DNA repair gene mutations (especially BRCA2). Genetic testing is essential — ask your doctor if you have been tested.²⁸ ²⁹
• Radiopharmaceuticals — radium-223 for bone metastases and Lu-177 PSMA-617 for PSMA-positive disease — deliver radiation directly to cancer cells from the inside. Both have proven survival benefits.³² ³⁵
• Treatment sequencing matters. What you receive first affects what works next. Cross-resistance between ARPIs limits sequential use. Genetic testing and biomarker-driven approaches increasingly guide therapy selection.¹⁸
• Castration-resistant does not mean untreatable. More than a dozen FDA-approved options exist, and research continues to expand the toolkit.

Support Resources

Patient advocacy and education:

• Prostate Cancer Foundation (PCF): pcf.org — the world's leading philanthropic funder of prostate cancer research; extensive patient education resources
• ZERO — The End of Prostate Cancer: zerocancer.org — advocacy, support groups, and a free helpline
• Us TOO International: ustoo.org — peer-to-peer support groups across the United States
• American Cancer Society: cancer.org — comprehensive cancer information and support services

Clinical trials:

• ClinicalTrials.gov — the U.S. government database of all registered clinical trials; search by disease, treatment, or location
• Prostate Cancer Clinical Trials Consortium (PCCTC) — a network of leading prostate cancer research centers

Bone health:

• Bone Health and Osteoporosis Foundation: bonehealthandosteoporosis.org

Cardiovascular health:

• American College of Cardiology Cardio-Oncology Council — resources for heart health during cancer treatment

Financial assistance:

• Patient Access Network (PAN) Foundation: panfoundation.org — helps cover out-of-pocket costs for medications
• HealthWell Foundation: healthwellfoundation.org — financial assistance for underinsured patients
• Manufacturer patient assistance programs — most ARPI and radiopharmaceutical manufacturers offer copay assistance or free medication programs for eligible patients

Mental health and emotional support:

• CancerCare: cancercare.org — free professional counseling, support groups, and financial assistance
• Man to Man (American Cancer Society) — prostate cancer support groups
• Movember Foundation: movember.com — men's health advocacy and support

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