Who, When, and How: Watchful Waiting in the ERSPC Rotterdam

Long-term data identifying which patients managed with watchful waiting (WW) ultimately require androgen deprivation therapy (ADT) are limited. Using 18-yr follow-up data from the Rotterdam section of the European Randomized Study for Prostate Cancer, we examined WW practices and identified prognostic factors for ADT initiation.

Men whose initial management strategy was WW were included and stratified by European Association of Urology risk group. WW practices were evaluated by the frequency of follow-up visits, prostate-specific antigen (PSA) testing, and imaging. Prognostic factors for ADT initiation were identified using a Fine-Gray competing risk model and used to predict 18-yr ADT-free survival for three hypothetical patients representing the risk groups.

We included 537 men with a median follow-up of 12.9 yr (interquartile range: 7.5-16.7). At 18 yr, cumulative incidence of ADT initiation was 6.6% (95% confidence interval [CI]: 0.02-13), 33% (95% CI 26-39), and 55% (95% CI 47-64) in men at low, intermediate, and high risk, respectively. Most patients received regular follow-up every 6 mo, regardless of risk group, whereas imaging was uncommon except in men at higher risk. PSA, grade group, and clinical T-stage were statistically significant predictors of ADT initiation. Predicted 18-yr ADT-free survival ranged from 90% in men at low risk to 35% in men at high risk. Limitations include the retrospective design, use of ADT initiation as an end point without standardized triggers, and a historical cohort, possibly affecting internal validity and generalizability.

Follow-up for men managed with WW could be individualized based on patient and tumor characteristics to reduce unnecessary visits while preserving timely detection of progression.