Tumor sidedness, adjuvant chemotherapy (AC), and other factors affecting survival in patients with stage II colon cancer (CC-II).
768 Background: The role of AC in CC-II is not well defined due to lack of conclusive randomized trial data. This updated analysis using National Cancer Database (NCDB) addresses the overall survival (OS) benefit from AC in CC-II using more refined and case appropriate population cohort. Methods: NCDB was queried for patients diagnosed with CC-II from 2004-2008 with survival information through 2013. Only those patients with pathologically confirmed CC diagnosis were included. Patients undergoing any surgical procedure less than a partial colectomy were excluded. Pearson Chi-square test, Kaplan Meier survival curves and Cox proportional hazards model were used for statistical analysis. Results: A cohort of 36,630 patients was identified for analysis. Elderly patients received less frequent AC (p < 0.0001) and AC was associated with an improved 5-year OS with no difference noted in outcomes from single or multi-agent regimens. AC was an independent predictor of OS regardless of age, gender, race, comorbidity index, insurance status, income level, year of diagnosis, tumor sidedness, tumor grade, adequacy of lymph node evaluation, pathologic tumor (pT) status, colectomy type, margin involvement or academic level of treating institution. In multivariate analysis, right-sided cancers had better survival outcomes compared to left-sided cancers (HR 0.91; p < 0.0001). Conclusions: This study validates previous findings of improved OS from AC in CC-II while addressing some of the shortcomings of prior retrospective studies. Only patients with CC-II without any other primary cancer diagnoses were included. To our knowledge this is the most uptodate analysis of AC in CC-II which includes cases diagnosed up to 2008. Our study found similar improvement in 5-year OS irrespective of chemotherapy regimen. Interestingly, improved OS was seen in right sided tumors compared to left sided tumors, in contrary to that seen with metastatic colon cancer (Venook et al). [Table: see text]