Most early-stage prostate cancers take a long time to progress. For this reason, older men with the disease may be offered the option of “watchful waiting” rather than immediate treatment, since the cancer may never become threatening during their lifetime.

However, new research shows that a substantial minority of prostate cancers will progress to an aggressive type after 15 years of watchful waiting.

Dr. Jan-Erik Johansson, from Orebro University Hospital in Sweden, and colleagues report the findings in this week’s Journal of the American Medical Association.

Although numerous reports have shown prostate cancer to be a relatively slow-growing malignancy, few studies have looked at disease progression and mortality beyond 15 years of watchful waiting.

To investigate, Johansson’s team assessed the outcomes of 223 men with early-stage prostate cancer who were followed for an average of 21 years. All of the patients were initially untreated, but those who experienced tumor progression that caused symptoms were given either surgical or medical hormone therapy.

During follow-up, the cancer progressed in 89 (40 percent) of the men.

Most of the cancers followed a slow-moving course during the initial 10 to 15 years, and during this period mortality due to prostate cancer was the equivalent of 15 deaths per 1000 men per year. After this point, the mortality rate rose to 44 per 1000 person-years.

“These findings would support early radical treatment, notably among patients with an estimated life expectancy exceeding 15 years,” the authors conclude.

SOURCE: Journal of the American Medical Association, June 9, 2004.