Dr Loblaw talks to ecancer about a study led by his colleague Dr Suneil Jain at the 2013 ASCO GU meeting looking at migration of Gleason grade with time in patients under active surveillance. This is the largest re-biopsy cohort, with long-term follow-up, described to date, enabling the first estimates of prostate cancer dedifferentiation in patients on AS. Dedifferentiation rates appear higher in patients with intermediate risk prostate cancer compared with those who are low risk at baseline.