Celecoxib plus chemoradiotherapy for locally advanced rectal cancer: a phase II TCOG study.

To report the results of a phase II trial combining celecoxib and preoperative chemoradiotherapy (CRT) for locally advanced rectal cancer. Patients with clinical stage II or III rectal cancer were treated with radiotherapy of 44 Gy in 22 fractions. Concurrent chemotherapy consisted of oral tegafur-uracil and folinate on days 1-30 and 38-65. Celecoxib (400 mg/day) given from days 1 to 65. Surgery was done on day 70. The expression of cyclooxygenase 2 (COX-2) in tumor tissues was evaluated microscopically as a prognostic factor. From 2008 to 2011, 53 patients completed CRT+ celecoxib therapy and 47 received radical surgery. Grade 3 diarrhea developed in 5 (9%). Grade 4 anemia was seen in 2 (4%). Pathological complete response (pCR) was seen in 6 (13%). T or N downstaging found in 38 (81%). Sphincter preservation was achieved in 77% of low-positioned tumors. Patients with tumors expressing high-level COX-2 after CRT + celecoxib treatment had inferior pelvic control (P = 0.01), disease-free survival (P = 0.04), and overall survival (P = 0.03) than those with low-level expression. Celecoxib can be safely combined with preoperative CRT for rectal cancer. More intensified adjuvant therapy may be considered for tumors expressing high-level COX-2 after CRT and surgery.