This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Prostate Cancer, Subject name: Surgery
[{'content': '70 year old man with prostate cancer was given radiotherapy. The recurrence of the cancer is monitored biochemically by \nSelect and explain. \nA. Androgens only, B. Prostate specific antigen and carcino-embryonic antigen, C. Prostate specific antigen only, D. ALP and CEA', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. (c) Prostate specific antigen onlyRef: Bailey & Love 26th ed. /1341* The most common presentation of advanced prostate cancer is a patient with a rising PSA level in whom initial local therapy has failed. Generally, after a radical prostatectomy, the PSA level should be less than 0.2 ng/ mL and, after radiation therapy, less than 0.5 ng/mL. Other important prognostic indicators include PSA velocity, time to PSA nadir, time to PSA recurrence, and pattern of PSA recurrence.* PSA levels for all men with prostate cancer who are having radical treatment should be checked at the earliest 6 weeks following treatment, at least every 6 months for the first 2 years and then at least once a year thereafter.', 'role': 'assistant'}]