While I am not permitted, in this forum, to provide specific medical advice, please know that your scenario is very, very common. In the PSA Era, many men are diagnosed with very early stage prostate cancer, such as having only one biopsy core positive for cancer and having a low (less than or equal to 6) Gleason grade. I assume your PSA level is also less than 10.0ng/ml and that the doctor could not feel a lump or nodule on your prostate when he/she did the digital rectal exam? If all these factors are favorable, (ie. Gleason 6 or less; PSA less than 10ng/ml; and a clinical stage T1c-nonpalpable tumor) then you have "Low Risk" prostate cancer and have a very high chance that the cancer is confined to the prostate gland and you would have an outstanding long term prognosis with treatments, such as surgery or radiation.
Treatment with active surveillance or watchful waiting is also becoming more commonly done by men with low risk disease. In general, this approach is best for men who have a more limited life expectancy of less than 10-15 years. You describe yourself as in "decent health" which could mean that you have more or less of a chance to survive more than 15 more years. If you do choose active surveillance, it is important to realize that it is a commitment. You will need to be seen regularly every 4-6 months for a check-up with a PSA test and a digital rectal examination (DRE). You will also likely need periodic repeat prostate biopsies-some doctors recommend repeat biopsies every year. You also run the risk of losing your window of opportunity for a cure of the cancer if it starts to spread in an occult way. Doctors around the world are still learning about how best to do active surveillance and a number of ongoing multicenter studies are further examining the best way to monitor men who are being followed without treatment. The bottom line is taking an honest assessment about your overall health and making a sound decision working with your doctors and your family.
Best wishes with your decision.
Dr. Moul