Which systemic regimen to choose in cisplatin-ineligible patients with concurrent radiation therapy for head and neck cancers: carboplatin/5-flurouracil or carboplatin/paclitaxel?

6090 Background: For locally advanced head and neck cancer, concurrent chemotherapy-radiation therapy (ChemoRT) is mainstay of treatment. Carboplatin and 5-Flurouracil (CF) is category 1 recommendation per NCCN guidelines and used mainly in Cisplatin ineligible patients. In this study we aim to compare the outcomes of concurrent radiation therapy with either CF or Carboplatin/Paclitaxel (CP). Methods: TrinetX, a global federated research network that provides a dataset of electronic medical records from different healthcare organizations (HCOs), was utilized. Initial query was made to isolate patients who had head and neck cancer (ICD 10 codes C02, C03, C04, C05, C06, C09, C10, C12, C13, C14, C32) and received radiation therapy, concurrently either with CP or CF. Further, propensity score matching (PSM) was carried out to match age, sex, and race. Outcomes of all-cause mortality (ACM), sepsis, septic shock, neutropenia, nausea/vomiting (NV), diarrhea were evaluated. Results: 8,310 cases were identified who received ChemoRT, of whom 26% (2,160) received CF. Caucasians were the predominant race in both groups, but Asians received more CF (14% vs 4%, p<0.0001). Patients receiving CF were younger (61.4 ± 9.87 vs 63.5 ± 10.4, p<0.0001). It was seen that patients who received CF had higher ACM rate (51.54% vs 48.52%, p=0.0163; median overall survival (OS) 571 days vs 781 days, p=0.0007). Risk of sepsis (21.24% vs 17.05%, p<0.0001), septic shock (7.11% vs 5.24%, p=0.0014), neutropenia (21.98% vs 17.05%, p<0.0001), NV (32.79% vs 28.58%, p=0.0003) was more with CF compared to CP, while no difference in neuropathy and diarrhea. After PSM, though elevated but no statistical difference was seen in ACM (50.95% vs 48.75%, p=0.1593), septic shock (7.09% vs 5.77%, p=0.0852), and neutropenia (22.10% vs 19.66%, p=0.0544), while there was still difference in sepsis (21.17% vs 17.8%, p=0.0065), and NV (33.74% vs 29.73%, p=0.0059). Conclusions: Concurrent chemoRT with CP offers similar efficacy compared to CF, with less toxicity and can be established as to go chemotherapy regimen with radiation therapy in patients who are ineligible for Cisplatin.