NEW YORK (Reuters Health) - Active surveillance of prostate cancer, with intervention offered for progressive disease, appears to be safe even for intermediate-risk disease in men over the age of 70, findings from a prospective cohort study suggest.
Although screening and early detection of prostate cancer reduces mortality, the risk of overtreatment is significant, comment Dr. Laurence Klotz and associates at the University of Toronto in the November 16th online issue of the Journal of Clinical Oncology.
However, older studies of watchful-waiting series of observation with no treatment option began prior to the availability of prostate specific antigen (PSA) testing and in nonscreened cohorts. As a result, cancer-specific mortality was relatively high.
Dr. Klotz and his team evaluated a watchful-waiting approach in which therapy was individualized according to the biologic behavior of the cancer.
The study cohort included favorable-risk patients (Gleason score 6 or less, PSA 10 ng/mL or less) as well as patients older than 70 years with PSA up to 15 ng/mL or Gleason score up to 7. Radical treatment was offered if PSA doubling time fell below 3 years or in the event of histological progression.
The favorable-risk subset represented 83% of the total group, according to the authors.
Out of 450 men (median age 70.3 years, median follow-up 6.8 years), only five died of prostate cancer within 10 years after diagnosis. Five- and 10-year cause-specific survival rates 99.75 and 97.2%, respectively. All five who died of prostate cancer had progressive disease and were offered radical treatment (radiation or surgery), which was turned down by two.
The overall survival was 78.6%, with most patients dying of other causes. The hazard ratio for non-prostate cancer to prostate cancer mortality was 18.6.
Overall, 125 patients were treated radically, and another 10 received androgen-deprivation therapy alone. Of 117 patients for whom posttreatment PSA levels were known, 59 (50.4%) had PSA failure.
The authors also observed that no one in the stable cohort of untreated patients has experienced clinical progression. In the overall cohort, the PSA failure rate was 13%, comparable to rates following radical prostatectomy or radiation for favorable-risk patients.
Furthermore, they add, “PSA failure does not mean death as a result of prostate cancer.”
The research team has initiated a prospective, randomized trial comparing surveillance to radical treatment among men reclassified as higher risk after a period of observation and repeat biopsy. Reference: J Clin Oncol 2009.
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