Increasing Neoadjuvant Radiation for Rectosigmoid Cancer: An Unintended Consequence of Modern Rectal Cancer Care?

BACKGROUND: Rectal cancer outcomes have improved with advances, including neoadjuvant radiation (NART), yet its utility for rectosigmoid cancer (RSJC) remains uncertain. We hypothesized that multimodality rectal cancer care has led to increased use of NART in rectosigmoid cancer (RSJC). Our objectives were to 1) assess the use of NART over time in RSJC and 2) identify factors associated with its use. METHODS: The National Cancer Database was reviewed (2004-2022) for adults with clinical Stage II-III rectosigmoid cancer who underwent surgery. The use of NART in these patients was examined over time, comparing stages. Multivariable logistic regression was used to identify patient and hospital factors associated with receiving NART. RESULTS: Of 49,506 patients, 8,591 (17.4%) received NART. Use increased over time in Stages IIIa (8.5% to 17.3%, OR 1.05, 95% CI 1.02-1.07) and IIIb/c (17.7% to 33.3%, OR 1.07, 95% CI 1.06-1.08). On multivariable analysis, factors associated with NART included male sex (aOR 1.24, 95% CI 1.17-1.32), lower Charlson-Deyo score (aOR 1.37, 95% CI 1.11-1.69, 0 vs 3), and higher stage (aOR 2.0, 95% CI 1.76-2.27 for IIIa; aOR 3.83, 95% CI 3.57-4.10 for IIIb vs II). Patients at high-volume hospitals (>26 cases/year) had lower odds (OR 0.71, 95% CI 0.61-0.82 vs <8/year). CONCLUSION: NART in RSJC increased over time for Stage III disease, with multiple factors influencing its use. Due to the lack of specific treatment guidelines for RSJC, a multidisciplinary review, standardized anatomic definitions, and development of data-backed guidelines are recommended.