Type of publication:
Conference abstract
Author(s):
*Arunachalam J.
Citation:
Annals of Oncology. Conference: The ESMO Gastrointestinal Cancers Congress. Barcelona Spain. 36(Supplement 1) (pp S87), 2025. Date of Publication: 01 Jul 2025.
Abstract:
Background: Basaloid squamous cell carcinoma (BSCC) of the anorectal region is a rare and aggressive variant of squamous cell carcinoma, arising primarily in the transitional zone of the anal canal and lower rectum. Historically referred to as cloacogenic carcinoma, BSCC is characterized by distinctive histological features. Chemoradiation remains the standard of care. Given its rarity, data on survival outcomes and demographic disparities are limited. We aimed to assess clinical characteristics and survival outcomes using a large U.S. population-based dataset. Method(s): We conducted a retrospective analysis using the SEER database (2000-2021) to identify patients with BSCC, defined by ICD codes 8083/3 and 8124/3, located in C21.0, C20.9, C21.1, C21.2, and C21.8. Variables extracted included age, sex, race, tumor stage, and treatments. Kaplan-Meier survival analyses were used to assess overall survival (OS) and cancer-specific survival (CSS). Group comparisons were evaluated using the log-rank test. Result(s): A total of 3,446 patients were identified. At diagnosis, 54% were under 65 years, 75% were female, and 80% were White. Metastatic disease was present in 11%. Median OS (mOS) was 120 months. The 1-, 3-, and 5-year CSS rates were 91.1%, 78.9%, and 73.3%, respectively; 10- and 20-year CSS rates were 67.4% and 61.5%. Male patients had poorer survival (mOS 66 months) compared to females (mOS 143 months; p < 0.0001; HR 1.595, 95% CI 1.420-1.791). Patients aged >=65 had a mOS of 72 months versus 219 months for those <65 (p < 0.0001; HR 2.124, 95% CI 1.926-2.342). Median OS by stage was 25 months (metastatic), 124 months (regional), and 175 months (localized) (p < 0.0001). Patients undergoing surgery had a mOS of 154 months, and those receiving radiation therapy had a mOS of 134 months. Lack of chemotherapy was associated with worse survival (mOS 50 months; HR 1.780, 95% CI 1.570-2.020; p < 0.0001). Race was not significantly associated with survival differences. Conclusion(s): Favorable outcomes were associated with younger age, female sex, early stage, and chemotherapy. Future studies should refine treatment strategies and explore targeted therapies in BSCC to guide precision medicine. Legal entity responsible for the study: The authors. Funding(s): Has not received any funding. Disclosure: All authors have declared no conflicts of interest.
DOI: 10.1016/j.annonc.2025.05.230
