A case report of a pathological complete response of rectal cancer to preoperative chemoradiotherapy with tegafur

We report the case of a patient with advanced rectal cancer who achieved a pathological complete response to preoperative chemoradiotherapy (CRT). A 65-year-old man was diagnosed as having a two-thirds circumferential well- to moderately differentiated tumor (Rb-P, type 2). To control local recurrence, we treated the patient with CRT. Radiotherapy was administered in fractions of 2 Gy/day (total, 40 Gy). Concurrently, S-1 was administered orally at a fixed daily dose of 80 mg/m² for 20 days. Withdrawal and/or dose reduction of S-1 was not necessary in spite of Grade 1 or 2 toxic effects, including diarrhea and periproctitis, occurring on day 7. Laparoscopic abdominoperineal resection was performed 6 weeks after the final dose of chemotherapy was administered. The histopathological regression grade was Grade 3. No recurrence was detected on enhanced CT more than 5 years after surgery. This case suggests that the regimen was both effective and tolerated, and that preoperative chemoradiotherapy may be effective for tumor suppression to prevent local recurrence.