J. Watson1, M. Turner1, Z. Sun1, D. Becerra1, J. Migaly1, C. Mantyh1, D. Blazer1 1Duke University Hospital,Department Of General Surgery,Durham, NC, USA
Introduction: Recent studies have observed differences in overall survival and response to chemotherapy in left compared to right-sided colon cancer. This suggests biologic differences within tumor laterality. We evaluated the impact of left compared to right-sided primary tumors on overall survival for patients with stage I-III and stage IV colon cancer in both operative and non-operative cohorts, utilizing a large national cancer database.
Methods: The 2006-2013 National Cancer Data Base was queried for patients with single primary, stage I-IV colon adenocarcinoma. Patients were grouped by stage and tumor location based on embryologic boundaries. Left side was defined as splenic flexure to the sigmoid colon, and right side was defined as cecum to transverse colon. Patients with appendiceal, overlapping, or unspecified tumor locations were excluded. Overall survival was compared using Cox Proportional Hazard modeling while adjusting for demographic, clinical, and tumor characteristics. The analysis was conducted separately for patients who had operative and non-operative management (stage IV) of the primary tumor.
Results: For stage I-II tumors, 114,839 patients underwent resection, 62% for right and 38% for left-sided tumors. After adjustment for patient and tumor characteristics, patients with right-sided tumors had superior survival compared to those with left-sided tumors (HR for left-sided tumors, right-sided reference [HR]: 1.13, p<0.001). For Stage III tumors, 71,024 patients underwent resection (59% right-sided, 41% left-sided tumors). Of 60,788 patients with stage IV tumors, 41,371 (68%) patients underwent resection (57% right-sided, 43% left-sided). For the 19,417 patients with stage IV cancer who did not undergo surgery, 56% were right-sided tumors, and 44% were left-sided tumors. After adjustment for patient and tumor characteristics, left-sided tumors had superior survival compared to right-sided tumors in Stage III tumors, Resected Stage IV tumors, and Unresected Stage IV Tumors with respective Hazard Ratios of Stage III 0.90, p<0.001, Stage IV Resected HR 0.71, p<0.001, and Stage IV Unresected HR 0.77, p<0.001.
Conclusion: Primary tumor laterality affects overall survival across stages for colon adenocarcinoma. In this analysis, patients with right-sided tumors have superior survival for stage I-II disease. However, left-sided tumors have superior survival in advanced disease, stage III-IV. These results from a large, national cancer database reinforce and extend previous subgroup analyses of large cooperative group trials. These findings provide investigators better prognostication tools and provide a possible avenue to better understand the molecular mechnisms in patients with colon adenocarcinoma.
