Financial Toxicity as an End Point in Prospective Clinical Trials Involving Radiation Therapy

Prior research, predominately retrospective, has increased awareness that patients with cancer are at elevated risk for financial toxicity (FT). Radiation therapy (RT) can be particularly disruptive due to weeks of daily treatments. Yet, FT in patients receiving RT is less studied, and the extent to which FT has been incorporated as an end point in prospective clinical trials involving RT is unknown. Clinicaltrials.gov was queried to identify all observational or interventional studies from 2001 to 2020 wherein RT was administered for cancer. Studies with primary, secondary, or exploratory FT end points were identified through keyword search. For trials incorporating FT outcomes, pertinent study characteristics were collected. Detailed information regarding FT measures was recorded. Descriptive statistics, including frequency counts and proportions, were performed. The overall rate of inclusion of FT end points was calculated, and rates over 5-year intervals were compared using the χ² test (α = 0.05). Overall, 10,550 studies involving RT were identified, of which 88 reported FT end points (0.8%). Included FT end points were typically secondary (78%), with just 15 studies (17%), including primary end points. Notably, only 19 studies (22%) reported a standalone FT end point. The majority measured FT as part of a larger quality of life (QoL) questionnaire. The rate of inclusion of FT end points significantly increased over time from 0.1% from 2001 to 2005 to 1.5% from 2016 to 2020, (P < .0001). FT is a major stressor for patients with cancer, yet even after a relative increase over time, the absolute rate of inclusion of FT end points remains low among RT-based trials. When included, FT outcomes were typically a single question within a QoL assessment not validated as a standalone measure of FT, preventing meaningful study and inference. To characterize and mitigate this burden more accurately, future prospective studies should include FT end points with greater frequency.