Although the PSA test may help to detect a cancer early, there is no certainty that treating early prostate cancers helps men live any longer. Most men with early prostate cancer will not die as a result of it; this is particularly true of men in their 70s or 80s, or with a slow-growing cancer.
It is also worth bearing in mind that if you have surgery or radiotherapy (the two main treatments for early prostate cancer), there can be effects such as erection problems, leaking of urine (incontinence) or damage to the rectum (back passage).