Watchful waiting is based on the premise that cases of localized prostate cancers may advance so slowly that they are unlikely to cause men–especially older men–any problems during their lifetimes. Some men who opt for watchful waiting, also known as "observation" or "surveillance," have no active treatment unless symptoms appear. They are often asked to schedule regular medical checkups and to report any new symptoms to the doctor immediately.
Watchful waiting has the obvious advantage of sparing a man with clinically localized cancer, who typically has no symptoms, the pain and possible side effects of surgery or radiation. On the minus side, watchful waiting risks decreasing the chance to control disease before it spreads, or postponing treatment to an age when it may be more difficult to tolerate. Of course, treatments may also improve over time if watchful waiting is chosen. Another potential disadvantage is anxiety; some men don't want the worry of living with an untreated cancer.
The most obvious candidates for watchful waiting are older men whose tumors are small and slow-growing, as judged by low grade Gleason score and low stage.
Many men who choose watchful waiting live for years with no signs of disease. A number of studies have found that, for at least 10 or even 15 years, the life expectancy of men treated with watchful waiting (primarily older men with less lethal forms of prostate cancer) is not substantially different from the life expectancy of men treated with surgery or radiation–or, for that matter, of the population at large.