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Suspected prostate cancer during long-term finasteride treatment — MSRA MCQ

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HardPSASuspected prostate cancer during long-term finasteride treatmentMSRA

A 73-year-old man has taken finasteride 5 mg daily for benign prostatic enlargement for 3 years. Before treatment, his prostate was estimated at 45 g, digital rectal examination was benign and his PSA was 4.0 micrograms/L. After 6 months of treatment, his PSA stabilised at 1.9–2.0 micrograms/L. He now reports increasing hesitancy and nocturia. Digital rectal examination shows smooth, symmetrical enlargement. His PSA is 3.6 micrograms/L. Urinalysis and urine culture are negative, and he confirms good adherence to finasteride. He has had no recent urinary infection or prostatic procedure and avoided ejaculation and vigorous exercise before testing. A repeat PSA 4 weeks later, under the same conditions, is 3.7 micrograms/L. Which is the most appropriate next step?

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Correct answer: A — Continue finasteride and make a suspected cancer pathway referral

Explanation lettering: C = shown as A · A = shown as C · E = shown as D · D = shown as E

Finasteride reduces PSA by approximately 50%. Once treatment has continued for at least 6 months, the measured PSA should be doubled when comparing it with reference ranges for untreated men. His confirmed PSA of 3.7 micrograms/L therefore corresponds to approximately 7.4 micrograms/L, exceeding the NICE threshold of more than 6.5 micrograms/L for a symptomatic person aged 70–79. The result is also a sustained rise from his established finasteride-associated baseline of about 2.0 micrograms/L. Adherence has been confirmed, important transient causes have been excluded, and the rise persists on repeat testing. A benign digital rectal examination does not remove the indication to consider referral. Finasteride should be continued while a suspected cancer pathway referral is made. A would delay assessment despite an already confirmed rise above the adjusted threshold. B is unnecessary: stopping finasteride is not required to interpret PSA and would disrupt the established longitudinal baseline. D may improve bothersome voiding symptoms, but symptom treatment must not take priority over investigation of possible malignancy. E is not an appropriate gatekeeper to referral; finasteride does not materially alter the free-to-total PSA ratio, but NICE referral decisions in this context are based on the valid age-adjusted total PSA and clinical presentation.

Reference: Finasteride 5 mg film-coated tablets — Summary of Product Characteristics (Text revised 10 September 2025; emc updated 17 September 2025) — https://www.medicines.org.uk/emc/product/13543/smpc Suspected cancer: recognition and referral — Recommendations organised by site of cancer (Guideline last updated 15 April 2026; recommendation 1.6.3 updated 2021) — https://www.nice.org.uk/guidance/ng12/chapter/recommendations-organised-by-site-of-cancer PSA test (Reviewed 2 September 2024) — https://www.nhs.uk/tests-and-treatments/psa-test/