The Enigma That is Rectal Squamous Cell Carcinoma: A Case Series.

INTRODUCTION: Colorectal cancer is the third most common cancer and the third leading cause of cancer deaths in the United States. As rectal squamous cell carcinoma (SCC) is an uncommon colorectal cancer, there is limited data on this clinical entity. We aimed to evaluate the tumor characteristics, treatment, and clinical outcomes of this rare deadly disease.

METHODS: Pathological specimens from 2017 to 2022 at a single National Cancer Institute-designated cancer center were screened for all rectal cases with a diagnosis of SCC. All patients with a primary rectal SCC were included. Patients who had extension to the dentate line or evidence of an anal mass, and those who were treated at an outside institution, were excluded. Demographic, treatment, outcome, and surveillance data was extracted.

RESULTS: There were 56 specimens identified, nine of which met inclusion criteria. Most patients were White (78%), Hispanic (78%), and female (67%). The average age at diagnosis was 57 y [52-65]. All patients had nodal involvement at the time of clinical staging. All patients were treated with Nigro protocol, with one patient treated with surgery first. The median time of follow-up was 12 mo after initial treatment, 33% had recurrence, with median time to recurrence of 25 mo. Overall, mortality from rectal SCC was 33% at a median time of 37 mo from initial diagnosis.

CONCLUSIONS: Rectal SCC is a colorectal cancer that is not fully understood. Our findings showed that treatment mirrors that of anal SCC, with similar rates of survival to both rectal adenocarcinoma and anal SCC.