Overall side effect assessment of oxaliplatin toxicity in rectal cancer patients in NRG oncology/NSABP R04

Purpose: Regulatory guidance suggests capturing patient-reported overall side effect impact in cancer trials. We examined whether the Functional Assessment of Cancer Therapy (FACT) GP5 item (“I am bothered by side effects of treatment”) post-neoadjuvant chemotherapy/radiotherapy differed between oxaliplatin vs. non- oxaliplatin arms in the National Surgical Adjuvant Breast and Bowel Project (NSABP) R-04 trial of stage II–III rectal cancer patients. Methods: The R-04 neoadjuvant trial compared local-regional tumor control between patients randomized to receive 5-fluorouracil or capecitabine with radiation, with or without oxaliplatin (4 treatment arms). Participants completed surveys at baseline and immediately after chemoradiotherapy. GP5 has a 5-point response scale: “Not at all” (0), “A little bit” (1), “Somewhat” (2), “Quite a bit” (3), and “Very much” (4). Logistic regression compared the odds of reporting moderate-high side effect impact (GP5 2–4) between patients receiving oxaliplatin or not after chemoradiotherapy, controlling for relevant patient characteristics. We examined associations between GP5 and other patient-reported outcomes reflecting side effects. Results: Analyses were performed among 1132 study participants. Participants receiving oxaliplatin were 1.58 times (95% CI: 1.22–2.05) more likely to report moderate-high side effect bother at post-chemotherapy/radiation. In both arms, worse overall side effect impact was associated with patient-reported diarrhea, nausea, vomiting, and peripheral sensory neuropathy (p < 0.01 for all). Conclusion: This secondary analysis of R-04 found that GP5 distinguished between patients receiving oxaliplatin or not as part of their post-neoadjuvant chemoradiotherapy, adding patient-centric evidence on the reduced tolerability of oxaliplatin and demonstrating that GP5 is sensitive to known toxicity differences between treatments. ClinicalTrials.gov: NCT00058474.