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

Background: To report the results of a phase II trial combining celecoxib and preoperative chemoradiotherapy (CRT) for locally advanced rectal cancer.

Patients And Methods: 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.

Results: 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.

Conclusions: 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.