Background: There has been no comparative study of the long-term oncological outcomes of appendiceal cancer and colon cancer. We hypothesized that the oncological outcome is worse in appendiceal cancer because perforation is more frequent than in colon cancer.
Methods: Patients with stage I-III were selected from 5046 patients with appendiceal or colon cancer, between September 2001 and June 2010. The 5-year disease-free survival (DFS) was the primary endpoint. Multivariate analyses with Cox proportional hazards model for DFS and logistic regression model for perforation were conducted. A matching model was used to compensate for the heterogeneity between groups.
Results: The perforation rate was 44.7% in appendiceal cancer (n = 47), but 1.1% in colon cancer (n = 2828) (p = 0.001). The 5-year DFS rate was lower in appendiceal cancer than in colon cancer (57.9% vs. 85.2%, p = 0.001; matching model, 54.2% vs. 78.4%, p = 0.038), with a higher rate of peritoneal seeding (25.5% vs. 2.5%, p = 0.001; matching model, 24.0% vs. 4.0%, p = 0.007). Multivariate Cox regression showed that appendiceal cancer was an independent prognostic factor for poor DFS (hazard ratio = 2.602, 95% confidence interval = 1.26-5.35, p = 0.009), and logistic regression confirmed that appendiceal cancer was the risk factor associated with perforation (odds ratio = 66.265, 95% confidence interval = 28.21-155.61, p = 0.001).
Conclusions: This study suggested that the long-term oncological outcomes are worse for appendiceal cancer than for colon cancer, attributed to higher perforation rate in appendiceal cancer.
Keywords: Appendiceal cancer; Colon cancer; Disease-free survival.
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