Active surveillance for prostate and thyroid cancers: evolution in clinical paradigms and lessons learned

The adverse effects of overdiagnosis and overtreatment observed in men with clinically insignificant prostate cancers after the introduction of prostate-specific antigen-based screening are now being observed in those with thyroid cancer, owing to the introduction of new imaging technologies. Thus, the evolving paradigm of active surveillance in prostate and thyroid cancers might be valuable in informing the development of future active surveillance protocols. The lessons learned from active surveillance and their implications include the need to minimize the use of broad, population-based screening programmes that do not incorporate patient education and the need for individualized or shared decision-making, which can decrease the extent of overtreatment. Furthermore, from the experience in patients with prostate cancer, we have learned that consensus is required regarding the optimal selection of patients for active surveillance, using more-specific evidence-based methods for stratifying patients by risk. In this Review, we describe the epidemiology, pathology and screening guidelines for the management of patients with prostate and thyroid cancers; the evidence of overdiagnosis and overtreatment; and provide overviews of existing international active surveillance protocols. Broad population screening of asymptomatic individuals for cancers of the prostate or thyroid has resulted in overdiagnosis and overtreatment. Herein, the authors describe the epidemiology, pathology, and screening guidelines for the management of patients with those cancers, and discuss existing international active surveillance protocols. Key points The harms of overdiagnosis and overtreatment that were observed in patients with prostate cancer following the introduction of prostate-specific antigen based screening are now being observed in those with thyroid cancer. Broad population-based screening can lead to the overdiagnosis and overtreatment of indolent cancers, as originally seen in prostate cancer and now also seen in thyroid cancer. Data from clinical trials demonstrate that active surveillance is an appropriate management strategy for patients with low-risk prostate cancer, and the results from similar trials in those with thyroid cancer are promising. Consensus is needed regarding both the optimal approach to patient selection for active surveillance and the most appropriate active surveillance scheduling and monitoring strategies. More specific methods of stratifying pat