You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is 70 year old man with prostate cancer was given radiotherapy. The recurrence of the cancer is monitored biochemically by and explain in detail?
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.