Cyproterone Acetate: Indications, Monitoring, and Discontinuation Criteria
Cyproterone acetate is indicated for prostate cancer, gender-affirming care in transgender women, and androgenic conditions such as hirsutism and acne, with monitoring required for hepatic function, adrenal suppression, and anemia, and should be discontinued if severe adverse effects occur. 1
Indications
Prostate Cancer
- Used as a second-line hormonal therapy for androgen-sensitive metastatic prostate cancer in Europe and Canada 2, 1
- Can reduce tumor flare when initiating LHRH agonist therapy for prostate cancer 1
- Less effective than goserelin when used alone for delaying progression of metastatic prostate cancer 1
Gender-Affirming Care
- Used as an antiandrogen component in hormone therapy for transgender women/transfeminine individuals 1, 2
- Produces feminizing effects through dual mechanisms: competitive inhibition of androgen receptor binding and suppression of testosterone production 1, 3
- Can be used alone initially or in combination with estrogens 3
Other Indications
- Treatment of androgenic conditions in women:
- Sexual disorders in men requiring androgen suppression 7
Dosing
- For prostate cancer: Used as second-line therapy 2
- For gender-affirming care: Often used in combination with estradiol 3
- For androgenic conditions in women: Often combined with ethinylestradiol (2mg CPA/0.035mg ethinylestradiol) 4, 6
Monitoring Requirements
Baseline Assessment
- Complete blood count to establish baseline hemoglobin and hematocrit 2
- Liver function tests 1
- Adrenal function assessment 2
- Blood pressure and weight 4
Ongoing Monitoring
- Regular liver function tests due to risk of hepatotoxicity, including potential for fulminant hepatic failure 2, 1
- Complete blood count to monitor for anemia 2
- Adrenal function tests to assess for adrenal suppression 2
- Blood pressure and weight monitoring 4
- In patients receiving combination therapy with estrogens, monitor for:
Frequency of Monitoring
- Liver function tests: Every 3-6 months, more frequently during initial treatment 1
- Complete blood count: Every 3-6 months 2
- Adrenal function: Periodically throughout treatment 2
Adverse Effects
Common Adverse Effects
- Fatigue and decreased energy 3, 7
- Breast tenderness and gynecomastia (in approximately 20% of male patients) 3, 7
- Emotional changes 3
- Hot flushes 3
Serious Adverse Effects
- Hepatotoxicity, including risk of fulminant hepatic failure 2, 1
- Adrenal suppression 2
- Anemia 2
- When combined with estrogens, increased risk of venous thromboembolism 5
Discontinuation Criteria
Absolute Criteria for Discontinuation
- Development of fulminant hepatic failure or severe hepatotoxicity 2, 1
- Severe anemia 2
- Significant adrenal suppression 2
Relative Criteria for Consideration of Discontinuation
- Persistent moderate elevation of liver enzymes 1, 6
- Development of venous thromboembolism when used in combination with estrogens 5
- Intolerable side effects such as severe fatigue, depression, or other mood disturbances 7
Special Considerations
- Contraindicated in patients with hereditary angioedema as it may worsen the condition 1
- Use with caution in patients with pre-existing liver disease 1
- When used for gender-affirming care, discontinuation may result in significant exacerbation of gender dysphoria, potential depression and/or anxiety 2
- In prostate cancer treatment, cyproterone acetate shows fewer cardiovascular side effects compared to diethylstilbestrol 1