Short course versus long course neoadjuvant radiation for patients with locally advanced rectal cancer (LARC): National Cancer Database (NCDB) analysis of the years 2004-2020.

e15606 Background: The two preoperative radiation approaches for LARC are long-course chemoradiotherapy (LC-CRT) and short-course radiation (SC-RT). While previous research suggested similar efficacy, the five-year follow-up of the RAPIDO trial revealed a significant increase in local recurrence rates with SC-RT. We aim to assess the outcomes and utilization patterns of both approaches in the United States of America (USA) using data NCDB. Methods: NCDB data for stage 2B, 2C, and 3 rectal cancer patients were obtained. SC-RT was defined as a total of 25 Gy in 5 fractions, and LC-CRT was defined as 45-60 Gy given over 5 to 6 weeks (with chemotherapy). Data was analyzed using JMP Pro V16. Results were considered significant at α = 0.05. Categorical data were compared using Fisher's or Chi-square test. Numerical data were compared using t-test or ANOVA. Post hoc analysis was conducted using Tukey's HSD. Survival rates were compared using the Kaplan-Meier method. Logistic regression was used to study outcomes' dependence on different factors. Firth adjusted maximum likelihood method was used to model likelihood of unstable outcomes due to biased estimates. Results: Out of the total 39,527 patients, 38,365 (97.06%) received LC-CRT, whereas only 1,162 (2.94%) received SC-RT. Only about 5% of patients received total radiation above 50.4 Gy. SC-RT was significantly more common among Hispanic patients (p = 0.0001), those with lower median income ( < $30,000) (p = 0.01), individuals with more comorbidities (p < 0.0001), and those treated at academic facilities (p < 0.0001). In comparison to SC-RT, LC-CRT demonstrated lower 30 and 90-day mortality after surgery, a higher pathological complete response (pCR) rate, and improved overall survival (OS) (Table). Upon subgroup analysis by stage, significant OS improvement with LC-CRT compared to SC-RT for stage 3 (p = 0.02), whereas no difference in OS was found in stage 2B, C. Detailed analysis will be presented. Conclusions: SC-RT is used by less than 3% of US patients and mainly in academic centers. LC-CRT is more effective, improving pCR and OS. Favorable outcomes with LC-CRT may be due to poor baseline performance status in SC-RT group. Prospective trials are needed to validate these findings. [Table: see text]