BackgroundResearchers remain divided on the major causes of dropout from active surveillance (AS), with rates of up to 38% among men with no evidence of prostate cancer (PC) progression. ObjectiveTo develop and evaluate an educational intervention in terms of adherence to AS among men with low- to intermediate-risk PC. Design, setting, and participantsWe first carried out focus group discussions with men who had remained on and dropped out of AS to inform an intervention to increase adherence to AS. A total of 255 consecutive men who had selected AS were then recruited to either standard care (written information and access to a nurse specialist) or standard care and the intervention. InterventionAn educational seminar was designed by patients and clinicians including information on imaging, biopsy techniques, understanding pathology, large AS cohorts - mortality and morbidity risk and diet and lifestyle advice. Outcome measurements and statistical analysisThe proportion of men dropping out of AS for reasons other than disease progression was assessed at 1 and 5yr after AS selection using multivariate logistic regression. Results and limitationsCommon themes influencing decision-making by men on AS were identified: (1) clinical consistency; (2) information; and (3) lifestyle advice. Addition of an educational seminar led to significantly fewer men dropping out of AS: at 1 and 5yr the dropout rate was 25% and 42%, respectively, in the standard care group, compared to 11% and 22% (p=0.001) in the intervention group. In the intervention group, 18 men failed to attend the seminar. ConclusionsThe AS dropout rate was halved following a single educational seminar delivered to groups of men with intermediate- or low-risk PC, even at 5yr. Patient summaryMen on active surveillance (AS) for prostate cancer feel more supported when provided with an educational seminar within 3 mo of their treatment choice. The seminar halved the number of men dropping-out of AS, even at 5yr.