Squamous-cell carcinoma of the rectum: a rare but curable tumor.

PURPOSE: This study was designed to evaluate one institution's experience with treatment outcomes for rectal squamous-cell carcinoma.

METHODS: Using our prospective Colorectal Database, we identified patients diagnosed with rectal squamous-cell carcinoma at our institution between 1983 and 2005. Pathology was rereviewed, tumor immunophenotype was compared to control cases of anal squamous-cell carcinoma and rectal adenocarcinoma, treatment modalities and outcomes were analyzed.

RESULTS: Twelve patients were identified (10 females median age, 58 years). Median distal extent of tumors was 7 (range, 5-8) cm from the anal verge. Treatment included chemotherapy only (n = 1), chemoradiation only (n = 2), induction chemotherapy followed by chemoradiation and surgery (n = 2), chemoradiation followed by surgery (n = 5), and surgery followed by chemoradiation (n = 2). The chemotherapy regimen was 5-fluorouracil-based. Radiotherapy total dose was 50.4 Gy (1.8 Gy/day, daily x 5) external iliac and inguinal nodes were not included in the radiation field. Complete clinical responders to chemoradiation (n = 2) received no further treatment. All seven partial responders underwent surgery; six had complete pathologic response; nodal status in two of six was unknown because they had local excision. Immunophenotypical analysis showed similar keratin expression profile between rectal squamous-cell carcinoma (n = 5) and rectal adenocarcinoma (n = 5), which is different from anal squamous-cell carcinoma (n = 10). All patients were alive without evidence of disease at follow-up (median follow-up, 2.6 (range, 0.5-16) years).

CONCLUSIONS: Our data suggest that most patients treated with upfront chemoradiation therapy followed by surgery did well. Sphincter-preserving surgery is usually feasible. Clinical judgment of tumor response after chemoradiation is not completely reliable. Immunohistochemistry suggests a common cellular origin for rectal squamous-cell carcinoma and rectal adenocarcinoma, which is different from anal squamous-cell carcinoma.