An analysis of Surveillance, Epidemiology and End Results (SEER)-Medicare records for 44,630 older men suggests surgery or radiation therapy for early-stage prostate cancer increased the lifespan of men between 65 and 80 years old compared to observation, sometimes known as "watch and wait." Published in the Dec. 13 issue of Journal of the American Medical Association, the study supported a benefit of treatment even for men whose disease had a low risk of spreading, and even if they were elderly men (75 to 80 years old).
"Studies have shown that low- and intermediate-grade prostate cancers may grow slowly, and many patients may never suffer complications from their disease. This makes decisions regarding treatment complicated for patients and their families," said lead author Yu-Ning Wong, M.D., a medical oncologist at Fox Chase Cancer Center who authored the study with colleagues at the University of Pennsylvania. "In our study, we looked back at existing data that tracked long term outcomes of elderly men whose cancer was at low and intermediate risk of spreading. After accounting for all of the observed differences between the groups, we found that men who had either a radical prostatectomy or radiation therapy within six months of their prostate cancer diagnosis were 30 percent less likely to die than those who did not undergo treatment during this time period," she said.
Researchers confined the study sample to men with small tumors (clinically designated as T1 or T2) with well-differentiated (corresponding Gleason score 2 to 4) or moderately differentiated (corresponding Gleason score 5 to 7) prostate cancers, who were diagnosed between 1991 and 1999.
Of the 44,630 patients included in the study, 12,608 (28.3 percent) were not treated while 32,022 (71.8 percent) were actively treated. In the treatment group, 88 percent lived five years or longer and 66 percent lived 10 years or longer. In the non-treatment group, 78 percent lived five years or longer and 51 percent lived 10 years or longer. The benefit of treatment was still present after adjusting for differences between the treatment and non-treatment groups, including patient demographics and tumor characteristics.
Since the study was a retrospective analysis of existing data (observational) rather than a randomized controlled trial, the authors noted that treatment and non-treatment groups may differ in measured and unmeasured ways that are associated with differences in survival.
"Observational studies such as ours should be interpreted with caution, since men who were offered treatment, or specific types of treatment, may have been ‘healthier' than men who were not offered treatment, which raises the possibility that the treatment benefit may due to the selection of healthier men," Wong noted. "We performed extensive statistical adjustments to account for these differences and still found that treatment was associated with longer survival."
Wong emphasized that observation is a reasonable choice for many men since some prostate cancers grow slowly. Studies have shown that in recent years, only between 7 and 17 percent of men in the U.S. with low-risk localized prostate cancer choose observation rather than treatment.
Longer survival alone is not the only factor in choosing treatment over observation, Wong pointed out. "The risks of treatment have decreased as options have improved including more targeted radiation therapy that reduce side effects and less invasive surgical techniques, but both may be associated with bowel, bladder and sexual dysfunction. Patients should talk to their doctors about their risks of side effects associated with radiation, surgery and observation before making treatment decisions."
"Our study is just one piece of an extraordinarily complex puzzle, and many other researchers are examining different aspects of prostate cancer biology and treatment. Patients should consider enrolling in clinical trials and other research protocols to help us better understand how prostate cancer grows and which patients most likely to benefit." Wong concluded.
Karen Mallet | EurekAlert!
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