Tehran University of Medical Sciences Iranian Journal of Public Health 2251-6085 52 9 2023 08 27 1935 1941 Qi Shen Department of Radiation Oncology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui,230001, China Dandan Liu Department of Geriatric Medicine, The Second People’s Hospital of Hefei (Hefei Hospital Affiliated to Anhui Medical Universi-ty), Hefei, Anhui, 230001,China Shaojun Liu Department of General Surgery, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, 230001,China 2023 03 15 2023 08 27 Background: Neoadjuvant chemoradiotherapy is recommended to locally advanced rectal cancer, especially for the lower and middle ones. However, the role of neoadjuvant chemoradiotherapy in rectosigmoid junction cancer remains undetermined. We investigated whether patients with a good response to neoadjuvant chemoradiotherapy will have a relatively better long-term survival compared with those with no response. Methods: Overall, 1325 patients diagnosed with locally advanced rectosigmoid junction cancer from Surveillance, Epidemiology, and End-Results (SEER) cancer registry database (2004-2014, America) were selected. All of them had received neoadjuvant chemoradiotherapy and were evaluated by Collaborative Stage Data Collection System. We performed Kaplan–Meier univariate analysis and Cox regression multivariate analysis models to estimate the potential prognostic factors of long-term survival outcomes. Response to neoadjuvant chemoradiotherapy and histological type of tumor were the two prognostic factors. Results: The 5-year OS was 78.1% in responders, and 63.4% in nonresponders. In addition the 5-year DSS was 85.1% in responders, and 72.9% in nonresponders. Conclusion: Based on SEER database in locally advanced rectosigmoid junction cancer, patients with a good response to neoadjuvant chemoradiotherapy could have a benefit of long-term survival. https://ijph.tums.ac.ir/index.php/ijph/article/view/31480 https://ijph.tums.ac.ir/index.php/ijph/article/download/31480/8037