Epidemiology, survival outcomes, and impact of treatment modalities in rectal squamous cell carcinoma: A SEER database study.

e15680 Background: Rectal cancers represent 35% of colorectal cancers; 90% are adenocarcinomas, while squamous cell carcinoma accounts for only 0.3% of them. Due to its rarity, there is limited understanding of its epidemiology, survival outcomes, and treatment strategies. This study aims to evaluate incidence trends, survival outcomes, and the impact of treatment modalities in RSCC patients. Methods: The Surveillance, Epidemiology, and End Results (SEER) Database was queried for histologically confirmed RSCC cases from 2000 to 2021. Data on tumor stage, intervention, histology, and survival were extracted. Statistical analyses, including multivariable Cox proportional hazard models, were performed using Stata 18.5 (STATA Corp., College Station, TX, USA). Results: A total of 326 patients with biopsy confirmed RSCC were identified. The age-adjusted annual incidence rate was stable at 0.1–0.7 per 100,000 population, with the highest incidence (21%) observed in the 60–64 age group. Patients aged 80–85 years demonstrated the worst median survival of 18 months (p = 0.01). Higher incidence was noted among White (89%) females (72%), but survival outcomes were not influenced by race (p = 0.49) or sex (p = 0.19). At diagnosis, 47.85% had localized disease, 40.18% had regional extension, and 11.96% had distant metastases. Treatment modality significantly impacted outcomes. Chemotherapy before surgery was associated with the longest median survival (98 months) compared to 64 months for chemotherapy after surgery (p = 0.03). Patients receiving chemotherapy both before and after surgery had a median survival of 83 months (p = 0.03). Radiotherapy, received either before (28%) or after (72%) surgery, did not significantly influence survival (p = 0.55). The overall median survival time for RSCC was 68 months. Conclusions: RSCC is a rare malignancy with stable incidence over the last two decades. Survival outcomes are significantly influenced by treatment modality, with chemotherapy before surgery yielding the best outcomes. These findings underscore the importance of optimizing treatment sequencing to improve prognosis in RSCC patients.