Does the primary site of colorectal cancer impact outcomes for patients with metastatic disease?

Abstract

BACKGROUND: Previous reports have described differences in biology and outcome for colorectal cancer based on whether the primary is right or left sided. Further division by right, left, and rectum or even exact primary site has also been explored. Possible differences in response to biological agents have also been reported based on side of primary lesion. METHODS: We explored the South Australian registry for metastatic colorectal cancer to assess if there were any differences in patient characteristics, prognostic markers, and treatment received and outcomes based on whether the primary was right or left sided.We also explored if differences exist based on left colon and rectum and by exact primary site. RESULTS: Two thousand nine hundred seventy-two patients were analyzed. Thirty-five percent had a right-sided primary. The median overall survival for the entire group right versus left was 9.6 versus 20.3 months (P