ASCO GU 2018: When Can Active Surveillance Be Less Active? Prediction of Long-term Non-reclassification for Men with Low-risk Prostate Cancer

San Francisco, CA ( Matthew Cooperberg, MD presented results of predictors of long-term non-reclassification for men with low-risk prostate cancer. Active surveillance is endorsed as the preferred management strategy for most men with low-risk prostate cancer. However, nearly all active surveillance protocols entail PSA testing every 3-6 months, and prostate biopsies every 1-2 years, with no defined taper/end point for vigorous surveillance.

For many men with indolent tumors, this regimen is overly intense, and exposes men to the discomfort, risks, and costs of repeated biopsies. As such, the objective of this study was to determine if some men can be safely selected for a less intense surveillance regimen by predicting the probability of non-reclassification over the next four years of surveillance.

For this study, the authors collected data from men in the multicenter Canary Prostate Active Surveillance Study (PASS), in which PSAs are collected every three months and biopsies performed 12 months after diagnosis and then every two years. For inclusion in this study, men had to have undergone ≤ 1 follow up biopsy, and have Gleason grade group 1 at diagnosis. Reclassification was defined as increase in Gleason grade group on subsequent biopsy. Those without reclassification were censored at last study contact, treatment or two years after last biopsy. Dr. Cooperberg and colleagues used a dynamic risk prediction model based on a Cox regression analysis with robust variance estimates to construct and test a model predicting non-reclassification. Among 1082 men included, 362 (33%) had reclassification and the remaining were censored. The final regression model included percent of biopsy cores involved, prior biopsy history, time since diagnosis, BMI, prostate size, diagnostic PSA, and PSAk (a measure of PSA kinetics). This prediction model was assessed at a measurement time of one year after diagnosis, predicting risk of reclassification at four years. Men at lowest and highest deciles of this model-based risk faced 6% (95%CI 0-12%) and 73% (95%CI 55-84%) risks of reclassification within five years, respectively. Furthermore, for at least 10% of the men in the cohort, the negative predictive value for reclassification was 95% or higher.

These authors concluded that a substantial proportion of men with low-risk prostate cancer can safely be followed with a de-intensified active surveillance protocol. This would certainly improve both the tolerability and cost-effectiveness of this management strategy, and may even improve adherence to active surveillance protocols.

Speaker: Matthew R. Cooperberg, MD, University of California San Francisco, San Francisco, CA

Co-Authors: Anna V Faino, Lisa F Newcomb, Peter Carroll, James T Kearns, James D. Brooks, Michael Fabrizio, Martin Gleave, Todd Matthew Morgan, Atreya Dash, Peter Nelson, Ian Murchie Thompson, Andrew Wagner, Daniel W. Lin, Yingye Zheng

Written by: Zachary Klaassen, MD, Urologic Oncology Fellow (SUO), University of Toronto, Princess Margaret Cancer Centre, Twitter:@zklaassen_md at the 2018 American Society of Clinical Oncology Genitourinary (ASCO GU) Cancers Symposium, February 8-10, 2018 - San Francisco, CA

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