Improvements in 5-year Outcomes of Stage II/III Rectal Cancer Relative to Colon Cancer

Abstract

Stage for stage, rectal cancer has historically been associated with inferior survival compared with colon cancer. Randomized trials of rectal cancer have generally demonstrated improvements in locoregional relapse but not survival. We compared therapy and outcomes of colon versus rectal cancer in 2 time cohorts to determine if relative improvements have occurred. Patients with resected stage II/III colorectal cancer referred to the British Columbia Cancer Agency in 1989/1990 and 2001/2002 were identified. The higher of clinical or pathologic stage was used for patients receiving preoperative chemoradiation. Disease-specific survival (DSS) and overall survival (OS) were compared for rectal and colon cancer between the 2 cohorts. Kaplan-Meier method was used for survival analysis. A total of 1427 patients were included, with 375 from 1989/1990 and 1052 from 2001/2002. Between 1989/1990 and 2001/2002 there were significant increases in the use of perioperative chemotherapy for both rectal and colon cancer (P<0.001) and use of preoperative radiation therapy (P<0.001) and total mesorectal excision (P<0.001) in rectal cancer. DSS significantly improved for rectal (P<0.001) but not colon cancer (P=0.069). Five-year OS was significantly inferior for rectal versus colon cancer in 1989/1990 (46.1% vs. 57.2%, P=0.023) and was similar to that of colon cancer in 2001/2002 (63.7% vs. 66.2%, P=0.454). Advances in locoregional and systemic therapy significantly improved survival among patients with rectal cancer. DSS and OS are now similar between colon and rectal cancer for both stage II and III disease.