NIH panel advocates delaying treatment for low-grade prostate cancer

Men with localized, low-risk prostate cancer should be closely monitored until disease progression warrants treatment, concluded an independent panel of the National Institutes of Health.

The panel issued a draft statement calling for standard definitions and for more multi-center studies to clarify which monitoring strategies are most likely to optimize patient outcomes.

The panel identified emerging consensus in the medical community on a definition for low-risk prostate cancer including a prostate-specific antigen (PSA) level less than 10 ng/mL and a Gleason score of 6 or less. Using this definition, the panel estimated that more than 100,000 men diagnosed with prostate cancer each year would be candidates for active monitoring rather than immediate treatment. About 10% of men who are eligible for active surveillance choose it, most often because of physician recommendation. About a quarter of patients who choose observation will subsequently undergo therapy within two to three years, and about half by five years.

The panel found that protocols to manage active monitoring still vary widely, hampering evaluation and comparison of research findings. For example, published studies show that PSA and digital rectal exams were variably assessed every three to 12 months, but no consensus exists as to the optimal schedule. Repeat biopsy is included in all U.S. studies of active surveillance, but frequency varies from one to four biopsy procedures during the initial four-year period, with surveillance continuing indefinitely.

“Predicting whether a particular individual's cancer will progress is difficult,” the report states. “The only clear current indicator of disease progression is an increase in Gleason score. The value of PSA doubling time is uncertain. New indicators of disease progression are needed, potentially including imaging techniques to identify clinical important tumors, molecular classification of cancers, and genetic classification of a patient's risk for progression.”

How clinicians frame disease management options is an important factor in patient decision-making, the panel said. The panel recommended against future federal funding for single-site studies, preferring multisite clinical research studies. The panel also supports creating registry-based cohort studies that collect longitudinal data on active monitoring participants, including clinical and patient-reported outcomes.

Finally, because of the very favorable prognosis of PSA-detected, low-risk prostate cancer, the panel recommended that strong consideration be given to avoiding the term “cancer” when talking to patients, because of the anxiety it creates.