Chemoradiation therapy with S-1 for primary squamous cell carcinoma of the rectum: report of three cases

PURPOSE: Although successful treatment of squamous cell carcinoma (SCC) of the rectum using chemoradiation therapy (CRT) has been reported, a standard protocol has yet to be established. The aim is to ascertain the effectiveness of CRT with S-1 for three patients with SCC of the rectum. CASE PRESENTATION: We treated three female patients complaining of rectal bleeding. The patients were diagnosed as having primary SCC of the rectum by means of routine examinations; one of them was a very rare case because of the presence of two lesions in the lower rectum. We treated the patients using CRT with S1 at a radiation dose of 1.8 Gy/fraction given five times weekly (Monday to Friday) to a median dose of 59.4 (45 to 59.4) Gy; S-1 (80 mg/m(2)/day) was administered orally during radiation therapy. One of three patients had an adverse event involving massive hemorrhage from the tumor. All patients exhibited an excellent response to CRT with S-1; two patients had a complete response, and one patient had a partial response and underwent a posterior pelvic exenteration with advancement flap reconstruction as a salvage treatment. Pathological examination of the resected specimen and lymph nodes revealed no tumor cells indicating a pathological complete response. In this series, the response rate was 100%. CONCLUSIONS: We suggest that CRT with S-1 be chosen as the first-line therapy for SCC of the rectum. However, a large study will be required to establish a safe and effective regimen.