[Effectiveness of preoperative chemoradiotherapy for advanced rectal cancer]

To determine the pathologic effectiveness of preoperative chemoradiotherapy (CRT) in patients with advanced rectal carcinoma, we reviewed clinical records of 76 patients who received preoperative pelvic radiation +/- chemotherapy. Since 2 patients refused operation and 2 died before surgery, 72 patients underwent operation with a mean delay of 19.9 days after completion of irradiation. Pathologic tumor regression grade (Grade 0-3) was determined by the amount of viable tumor versus necrosis and fibrosis. Grade 0, 1 a, 1 b, 2, and 3 (pCR) were observed in 0%, 25.0%, 38.9%, 27.8% and 2.8% of patients, respectively. The pathologic response (PR) rate was 75.0% when PR was defined as greater than grade 1 b (tumor regression more than 1/3). Downstaging was observed in 35.8% of patients, in which 5-year overall survival was significantly better than in patients without downstaging (90.0% vs. 50.1%, p<0.05). No correlation could be observed between PR and downstaging. CRT is a useful tool with a high PR rate in patients with advanced rectal cancer. More accurate and careful clinical staging is important to select adequate candidates for CRT. Multi-institutional clinical trials as well as standardizing the surgical procedure including LN dissection are required to validate the advantages of CRT for Japanese patients.