Tumor sidedness, recurrence, and survival after curative resection of localized colon cancer

Background Right-sided primary tumor location is associated with worse prognosis in metastatic colon cancer, but the effect of sidedness on recurrence, and prognosis for non-metastatic disease is less understood. The purpose of this study was to examine the relationship between sidedness, recurrence and survival among patients with localized colon cancer. Methods Consecutive patients who underwent curative resection of colon cancer (2006-2013) were identified from a prospective database and retrospectively analyzed. Risk for recurrence , overall survival (OS), and survival after recurrence (SAR) were compared between left- and right-sided tumors using the log-rank test, and multivariable Cox proportional hazards regression. Results We evaluated 673 patients (347 right-sided). There was no difference overall recurrence rates (adjusted hazard ratio [HR] = 0.92, 95% confidence interval [CI] 0.54 - 1.55; P = 0.75) or OS (HR =1.22, 95% CI 0.75-1.97; P = 0.42) between right- and left-sided primary tumors. However, right-sided tumors were more likely to develop multi-focal and poor prognostic site recurrence (P = 0.04). Among the 71 patients who developed recurrence, those with right-sided tumors had significantly lower SAR (HR = 3.88, 95% CI 1.42 – 10.62; P = 0.008). Conclusions Among colon cancer patients who underwent curative resection, tumor sidedness was not associated with recurrence risk. However, among patients who developed recurrence, right-sidedness was associated with unique recurrence patterns and inferior SAR. For patients presenting with localized disease, treatment stratification should not be based on tumor sidedness alone.