524 Background: Preoperative chemoradiotherapy (CRT) has been widely used to improve local control of disease and to preserve anal sphincter in the treatment of rectal cancer. However, the response to CRT differs among individual tumors. In ASCO 2008 Gastrointestinal Cancers Symposium, we reported that the patients with up-regulation of 17 genes were suggested to be good responder of CRT. Our purpose of this study was to evaluate the toxicity and efficacy of CRT using UFT versus S-1 and explore biomarkers for response in patients with locally advanced rectal cancer.
Fifty patients who received preoperative CRT (40Gy radiotherapy) were randomly assigned to either UFT or S-1. UFT and S-1 were administered during the radiotherapy course. S-1 was a novel oral fluoropyrimidine inhibitory for dihydropyrimidine dehydrogenase and had potent radiosensitizing property. Biopsy specimens were obtained from rectal cancer before preoperative CRT and were analyzed by focused DNA microarray (132 genes). To pick up the predictive factors, the 132 genes were selected in the view of sensitivity of 5FU. Response to CRT was determined by RECIST and histopathologic examination of surgically resected specimens and classified as responders (CR, PR and grade 2, 3) or nonresponders (SD, PD and grade 0, 1).
UFT group (n=25) and S-1 group (n=25) were enrolled. Response rate (grade 2 or 3) to CRT determined by histopathologic examination of surgically resected specimens was 58% in the UFT group and was 75% in the S-1 group. Response rate evaluated by RECIST criteria was 62% in the UFT group and was 77% in the S-1 group. National Cancer Institute Common Toxicity Criteria grade 2 or 3 toxicity was observed in 8% of the patients in the UFT group and 23% of patients in the S-1 group. Grade 2 or 3 toxicity in the UFT group was neutropenia and was diarrhea, neutropenia and dermatitis in the S-1 group. In ASCO 2010, we will report each candidate biomarker genes for response to CRT in the UFT and S-1 group.
The results have suggested that CRT using UFT or S-1 is feasible and effective for patients with locally advanced rectal cancer. [Table: see text].
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