Active surveillance for low-risk prostate cancer.

Abstract

The approach of active surveillance for low-risk prostate cancer has evolved in many ways since its introduction 20 years ago. There is a great deal of ongoing research addressing the molecular genetics and clinical outcome of low-risk disease, the use of MRI and biomarkers, and the role of lifestyle and dietary modifications. The major developments in the field are reviewed in this article. Low risk and many cases of low-intermediate risk prostate cancer are indolent, have little or no metastatic potential, and do not pose a threat to the patient in his lifetime. These are termed clinically insignificant. Studies over the last 20 years have advanced our understanding of who these patients are, and promoted the use of conservative management in such individuals. A key component of this approach is the early identification of those patients who have been misattributed as having low-risk disease, who in fact harbor higher risk disease and are likely to benefit from definitive therapy. This represents about 30% of newly diagnosed low-risk patients. A further small proportion of patients with low-risk disease demonstrate biological progression to higher grade disease. Extent of Gleason 6 on biopsy, Prostate Specific Antigen density, and race are predictors for the likelihood of coexistent higher grade cancer. The results of active surveillance, embodying conservative management with selective, delayed intervention for the subset who are reclassified as higher risk over time based on repeat biopsy, imaging, or biomarker results, have shown that this approach is safe in the intermediate to long term, with a 0.5-3% cancer-specific mortality at 10-15 years. Further refinement incorporating MRI and targeted biopsies is the subject of intensive research at the moment, and promises to improve the safety and precision of conservative management.