Planning posttherapeutic oncology surveillance visits based on individual risk.

The main objective of posttherapeutic surveillance in oncology is to detect recurrent disease associated with treatment failure. Current follow-up schedules are easy to apply because they are planned on a regular basis (for instance, every 3 months) but do not take into account prognostic factors associated with time to failure. We propose a 2-stage strategy to individualize surveillance by first identifying prognostic factors for time to failure, then modeling cumulative risk or cumulative incidence to plan visits according to equal quantiles of risk or probability of failure, respectively. Using data from a clinical trial of radiotherapy in non-small cell lung cancer patients, we demonstrate how this method could improve the early detection of relapse.