Treating advanced prostate cancer with radiation therapy after removal of the prostate gland reduces the risk of disease recurrence, but does not appear to significantly improve the length of survival, according to a study in the November 15 issue of JAMA, a theme issue on men's health.
Gregory Swanson, M.D., of the University of Texas Health Science Center, San Antonio, presented the findings of the study today at a JAMA media briefing on men's health in New York.
Radical prostatectomy (removal of the prostate gland) is selected for treatment of localized prostate cancer by approximately one-third of the 230,000 patients newly diagnosed each year in the United States. It is commonly accepted that this treatment has optimal results in patients with cancer confined to the prostate. But cancer outside of the prostate is detected at radical prostatectomy in 38 percent to 52 percent of patients, and this is associated with a risk of disease recurrence, progression, and death, according to background information in the article. Adding (adjuvant) radiation therapy to treatment has been used for more than 4 decades to reduce the risk of disease recurrence, but it is unknown if this reduces the risk of the cancer spreading or improves survival.
Dr. Swanson and colleagues conducted a study comparing usual care with adjuvant radiation therapy for 425 men with cancer outside of the prostate after radical prostatectomy to determine the effect on metastasis-free survival and overall survival. The patients were enrolled between August 1988 and January 1997, with median (midpoint) follow-up of 10.6 years. Men were randomly assigned to receive external beam radiotherapy (n = 214) or usual care plus observation (n = 211).
A total of 43.1 percent of the patients in the observation group were diagnosed with metastatic disease or died (median metastasis-free estimate, 13.2 years) vs. 35.5 percent of the patients in the adjuvant radiotherapy group (median metastasis-free estimate, 14.7 years), a difference that was not statistically significant. There were no significant between-group differences for overall survival (71 deaths in the radiotherapy group vs. 83 deaths in the observation group).
The researchers did find that patients in the adjuvant radiotherapy group had a 57 percent lower risk of PSA relapse, and a 38 percent reduced risk of disease recurrence, compared to patients in the observation group.
Adverse effects were more common with radiotherapy vs. observation (23.8 percent vs. 11.9 percent), including rectal complications and urinary incontinence.
"The results of this study provide guidance for clinicians and patients in weighing options for adjuvant radiotherapy for pathologically advanced disease. Arguments in favor of radiation include the approximately 50 percent reduction in risk of PSA relapse or disease recurrence, and perhaps the nonsignificant reduction in risk of metastasis-free survival, the primary study end point," the authors write. "Arguments against adjuvant radiotherapy must include that the study had negative findings, ie., a significant reduction in metastatic disease was not demonstrated. Despite prolonged follow-up of these patients, the rate of metastatic disease was significantly less than anticipated."