dr. otis brawley of the american cancer society. what does stage one mean exactly?> stage one means that the cancer's confined in the prostate. it's usually a very good prognosis cancer. many of these stage one tumors don't even need to be treated. >> in his letter to stockholders, he said he and his doctors decided on a two-month treatment of daily radiation to begin in july. why treat it? you say some of them don't need to be treated. is this standard? >> yeah. the national institutes of health made an announcement about 130,000 of these stage one tumors are diagnosed every year. and most of them can be watched and not treated. in the united states, most men choose to get it treated. younger men will usually choose surgery. older men will choose radiation. i personally believe it should be left to the patient and his doctor to decide what to do. many of these are such good prognosis tumors they can be watched. >> he said he discovered the cancer because his psa level jumped up. what is a psa level and is it what most people get checked? >> the antigen is a blood t