[A case of advanced rectal cancer that responded to S-1 with an extended complete response]

A 78-year-old female underwent an abdomino-perineal resection for lower rectal cancer with para-aortic, right iliac artery and left inguinal lymph node metastasis. Two weeks later, an enlargement of para-aortic and right iliac artery lymph node metastasis was detected by CT. S-1 (100 mg/day for 2 weeks followed by a 1-week rest period) + CPT-11 (120 mg/m2, day 1)treatment was initially administered. However, the patient developed grade 2 anorexia so this treatment regimen was terminated. After complete recovery from the adverse reaction, the regimen was converted to S-1 administration at 100mg/day S-1 for 2 weeks followed by a 1-week rest period. Eventually, this schedule was modified to 100mg/day for 1 week followed by a 1-week rest period. A year after the operation, CT revealed the lymph node metastasis to have disappeared, and no relapse occurred for 32 months. This was a successful case in which S-1 yielded an extended complete response for advanced rectal cancer. Treatment with S-1 is an effective choice for patients who for various reasons can not tolerate the standard treatment for unresectable advanced colorectal cancer. Moreover, randomized controlled trials have to be started to evaluate the efficacy of S-1 treatment for advanced rectal cancer as soon as possible.