Survival by first-line treatment type and timing of progression among follicular lymphoma patients

In follicular lymphoma (FL), progression of disease within 24 months has emerged as a popular prognostic marker for overall survival (OS). While it has considerable clinical relevance, there are also inherent limitations in relation to the fixed time point of 24 months and potential variation by treatment type and choice of comparison group. In this talk, I will highlight some of the methodical limitations and present the first results from a large population-based cohort of FL patients. National register-based information has been combined with detailed medical record data to create a unique cohort with detailed treatment and follow-up information. We allow progression to be time varying and estimate relative rates, as well as OS, by first-line treatment and timing of progression using an illness-death modeling approach. Stata packages merlin and multistate were applied, and example code will be presented. Our findings show that progression is associated with worse survival beyond the 24-month time point, illustrating the need for individualized management by timing of progression for optimal care of patients with FL.