3052 - Neoadjuvant Short-Course Radiotherapy Followed by Chemotherapy for Rectal Adenocarcinoma: Analysis of Clinical and Pathological Responses of Patients Treated in a Brazilian Tertiary General Hospital

D. Hütten, C. Tarta, R. P. Pereira, V. D. S. Stanham, L. L. Gaudie Ley, L. F. Fabra, and M. Nassif Pereira-Lima Sr; Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil

Purpose/Objective(s): To analyze clinical and pathological responses in patients with rectal adenocarcinoma that underwent neoadjuvant short-course radiotherapy followed by chemotherapy at a Brazilian tertiary general hospital from February 2020 to March 2023. Materials/

Methods: A retrospective cohort observational analysis was conducted on patients diagnosed with rectal adenocarcinoma that received total neoadjuvant therapy (TNT) with short-course radiotherapy followed by chemotherapy. Descriptive data were collected and analyzed using statistical software.
Results: Eighty-eight patients underwent neoadjuvant TNT treatment with short-course radiotherapy and chemotherapy, with 54% being male and a mean age of 63 years. Among them, 32.9% exhibited partial clinical response, while 21.6% achieved complete clinical response. Patients with complete clinical response were managed with a watch-and-wait strategy, resulting in tumor regrowth in 26% of cases. Among the 42 patients who underwent oncological surgery, 20% showed complete pathological response.
Conclusion: Clinical response and regrowth rates were consistent with international studies and protocols, supporting the use of neoadjuvant short-course radiotherapy followed by chemotherapy for rectal adenocarcinoma. Further longitudinal monitoring is required to objectively evaluate the long-term sustainability of the observed outcomes.