Metastasis More Than Doubles With Monitoring Instead of Treatment for Localized Prostate Cancer
Contrary to some news headlines, monitoring prostate cancer has different survival implications than treatment after 10 years.
Surveillance may spare men with early prostate cancer from immediate adverse effects, but forgoing treatment of disease with favorable characteristics may increase the risk of metastasis by 2-fold.
An editorial published in The New England Journal of Medicine by Anthony V. D'Amico, MD, PhD, from the department of radiation oncology at the Brigham and Women's Hospital and Dana-Farber Cancer Institute in Boston, Massachusetts, highlighted the risk of metastasis associated with surveillance compared with that of active treatment, based on the results of the ProtecT (Prostate Testing for Cancer and Treatment; ClinicalTrials.gov Identifier: NCT02044172) study, also published in the New England Journal of Medicine.1,2
The ProtecT study group reported the 10-year outcomes of men with localized prostate cancer who were randomly assigned to surveillance by prostate specific antigen (PSA) monitoring, treatment with radical prostatectomy, or external-beam radiotherapy. The men enrolled had favorable characteristics that closely resemble the type of patient for whom surveillance would be selected in practice: median age 62, mean PSA of 4.6 ng/mL, and T1c disease in 76%.
Despite these favorable disease characteristics, there was a more than 2-fold higher rate of metastasis in the monitoring arm compared with the treatment group. There was no difference in prostate cancer-related or all-cause mortality at 10 years, though longer-term data may show a difference.
“This is a missed but important observation. They focused on the cancer death rate, but they didn't comment on the doubling of the metastatic rate, which should have been much less likely when compared to prior studies,” Dr D'Amico told Cancer Therapy Advisor.
The SPCG-4 trial conducted in Sweden and the PIVOT study in the US evaluated similar outcomes, though the study populations were different and the control arm was watchful waiting instead of surveillance.3,4