Can bicalutamide (Casodex) or a Gonadotropin-Releasing Hormone (GnRH) analogue be used to reduce prostate size and perform a trial of voiding (TWOC) in a patient with significant cardiac risk?

Can Bicalutamide or GnRH Analogue Reduce Prostate Size for TWOC in High Cardiac Risk Patients?

Yes, both bicalutamide and GnRH analogues can effectively reduce prostate volume by approximately 37-39% within 3 months, making them viable options for cytoreduction before attempting TWOC in patients who cannot undergo embolization due to cardiac risk. 1, 2

Evidence for Prostate Volume Reduction

GnRH Analogues

• GnRH analogues (such as goserelin) achieve approximately 39% reduction in total prostate volume after 12 weeks of treatment 2
• These agents work by medical castration, reducing testosterone levels to <50 ng/dL, which subsequently shrinks prostatic tissue 1, 2
• Important caveat: GnRH agonists require flare protection with bicalutamide 50 mg daily for the initial 28 days to prevent testosterone surge that could worsen urinary obstruction 2

Bicalutamide Monotherapy

• Bicalutamide 150 mg daily as monotherapy has been studied for prostate volume reduction, though this dose is NOT FDA-approved 1, 3
• The FDA-approved dose of bicalutamide 50 mg is only indicated in combination with LHRH analogues, not as monotherapy 1
• Studies show bicalutamide 150 mg monotherapy preserves sexual function better than castration while achieving similar prostate volume reduction 3, 4

Practical Algorithm for Your Patient

Step 1: Choose the Appropriate Regimen

Recommended approach: Start GnRH analogue (goserelin 3.6 mg monthly) PLUS bicalutamide 50 mg daily 2

• This combination provides flare protection and achieves 37-39% volume reduction in 12 weeks 2
• Both medications should be started simultaneously 1

Alternative if GnRH analogue contraindicated: Consider bicalutamide 150 mg daily monotherapy (off-label use) 3, 4

• This preserves sexual function better but is not FDA-approved for this indication 1, 3
• Requires informed consent discussion about off-label use 1

Step 2: Monitoring During Treatment

• Measure PSA at baseline and monthly to assess response 5
• Monitor liver function tests (ALT/AST) at baseline, monthly for first 4 months, then periodically 1
• Critical warning: Discontinue bicalutamide immediately if ALT rises above 2x upper limit of normal or jaundice develops 1
• Check testosterone levels to confirm castrate levels (<50 ng/dL) if using GnRH analogue 1

Step 3: Timing of TWOC

• Plan TWOC attempt at 12 weeks after initiating androgen deprivation therapy 2
• At this timepoint, expect approximately 37-39% prostate volume reduction 2
• Assess symptom improvement using IPSS score—patients with baseline IPSS >13 show greater improvement with this approach 2

Cardiovascular Safety Considerations

Why This Approach is Safer Than Alternatives

• Androgen deprivation therapy avoids the procedural risks of embolization in your high cardiac risk patient 5
• However, be aware: Long-term ADT increases cardiovascular risk, including hypertension, hypercholesterolemia, and metabolic syndrome 5
• GnRH agonists may cause glucose intolerance—monitor blood glucose if patient has diabetes or prediabetes 1

Specific Cardiac Monitoring Required

• Baseline cardiovascular risk assessment before starting therapy 5
• Monitor for fluid retention if patient has history of congestive heart failure 5
• Screen for hypertension and hyperlipidemia during follow-up 5
• Consider cardiology consultation given patient's existing cardiac risk factors 5

Common Pitfalls to Avoid

Medication-Specific Issues

• Do not use bicalutamide 50 mg as monotherapy—this dose is ineffective alone and only approved in combination with LHRH analogues 1, 6
• Do not start GnRH agonist without flare protection—the initial testosterone surge can worsen urinary retention 2
• Do not ignore liver function monitoring—bicalutamide can cause hepatotoxicity requiring immediate discontinuation 1

Anticoagulation Interaction

• If patient is on warfarin or other coumarin anticoagulants, closely monitor PT/INR as bicalutamide can cause excessive prolongation leading to serious bleeding 1
• Check PT/INR within days to weeks after starting bicalutamide 1

Expected Side Effects to Counsel Patient About

• Gynecomastia and breast pain occur in up to 38-39% of patients on bicalutamide 1
• Hot flashes occur in 53% of patients on combination therapy 1
• Sexual dysfunction is common but better preserved with bicalutamide monotherapy than castration 3, 4

Alternative if Initial TWOC Fails

If TWOC is unsuccessful after 12 weeks of androgen deprivation:

• Continue ADT and consider surgical options (TURP, laser procedures) once prostate volume is reduced 5
• The volume reduction achieved makes subsequent surgical intervention technically easier and safer 5
• Reassess cardiac risk with cardiology before proceeding to surgery 5