February 23, 2015 – Orlando, Florida – An analysis of data on roughly 945 patients with prostate cancer managed with active surveillance has shown differences in outcomes depending on whether the cancer was low or intermediate risk at diagnosis. Compared to patients with low-risk disease, those with intermediate-risk cancer (prostate-specific antigen [PSA] >10 ng/mL or Gleason score 7 or clinical stage T2b/2c) had a nearly fourfold higher chance of dying from prostate cancer within 15 years.
This conclusion was announced the Genitourinary Cancers Symposium, held from February 26 to 28, 2015, in Orlando, Florida.
D. Andrew Loblaw, MD, of Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada, explained that active surveillance is a globally recognized standard approach for patients with low-risk prostate cancer and select intermediate-risk patients with prostate cancer. Cancer Care Ontario recently released guidelines recommending active surveillance as the preferred approach for low-risk patients. Patients on active surveillance undergo physical examinations, digital rectal examinations, PSA measurements, and repeat tumor biopsies. He said that this was the first study to examine long-term outcomes of patients with low- vs intermediate-risk prostate cancer managed on active surveillance.
The researchers analyzed prospectively collected data on 945 patients (237 with intermediate-, 708 with low-risk cancer) who were on active surveillance between 1995 and 2013. Overall and cause-specific survival for intermediate- and low-risk patients was analyzed as well as metastasis-free survival and treatment-free survival for intermediate-risk patients. Patients whose disease worsened during surveillance were offered treatment (radiation or surgery). In the intermediate-risk group, 86 patients 36.3%) received treatment.
A total of 237 (23.9%) patients had intermediate-risk disease, with a median follow-up of 6.9 years. A total of 708 patients had low-risk cancer, with a median follow-up of 6.4 years. A total of 61.2% of the intermediate-risk cohort was older than 70 years of age.
The 10-year and 15-year overall survival rates were 68.4% and 50.3% for intermediate-risk patients compared to 83.6% and 68.8% for low-risk patients. The lower survival rate for intermediate-risk patients offered active surveillance suggests that these patients had lower life expectancy. Patients with intermediate-risk disease had a 3.75 times higher chance of dying of prostate cancer compared to patients with low-risk disease (11.5% vs 3.7% at 15 years, respectively).
Dr. Loblaw concluded, “For low-risk patients with prostate cancer managed with active surveillance, the risk of dying of prostate cancer is low, validating this approach for this group of patients. More research, however, is needed to better characterize intermediate-risk patients who can safely be monitored in a surveillance program.” He urges extreme caution in using active surveillance for intermediate-risk patients.