Comparison of long-term oncological outcomes of appendiceal cancer and colon cancer: A multicenter retrospective study

• A comparative study for the oncologic outcomes of heterogeneous two malignancies.
• Worse oncologic outcome of appendiceal cancer compared with colon cancer.
• Perforation was associated with poor prognosis of appendiceal cancer.

BackgroundThere 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.MethodsPatients 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.ResultsThe 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).ConclusionsThis 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.