Abstract
The aim of the present study was to determine whether or not the overall survival (OS) and disease‐free survival (DFS) were affected by the tumor location in patients who underwent curative resection for colon cancer in a pooled analysis of three large phase III studies performed in Japan. In total, 4029 patients were included in the present study. Patients were classified as having right‐side colon cancer (RC) if the primary tumor was located in the cecum, ascending colon, hepatic flexure or transverse colon, and left‐side colon cancer (LCC) if the tumor site was within the splenic flexure, descending colon, sigmoid colon or recto sigmoid junction. The risk factors for the OS and DFS were analyzed. In the present study, 1449 patients were RC, and 2580 were LCC. The OS rates at 3 and 5 years after surgery were 87.6% and 81.6% in the RC group and 91.5% and 84.5% in the LCC group, respectively. Uni‐ and multivariate analyses showed that RRC increased the risk of death by 19.7% (adjusted hazard ratio = 1.197; 95% confidence interval, 1.020–1.408; P = 0.0272). In contrast, the DFS was similar between the two locations. The present study confirmed that the tumor location was a risk factor for the OS in patients who underwent curative treatment for colon cancer. Tumor location may, therefore, need to be considered a stratification factor in future phase III trials of colon cancer.
Highlights
Colorectal cancer is the third most commonly diagnosed cancer in males and the second most in females, with an estimated 1.4 million new cases and 693,900 deaths occurring in 2012 [1]
The present study examined whether or not the tumor location was associated with a poorer overall survival (OS) and disease-free survival (DFS) after curative surgery for colon cancer in combined analyses of individual patients’ data from the three large phase III studies evaluating the effects of adjuvant treatment
Our findings clearly indicated that the tumor location was a significant independent risk factor for the OS
Summary
Colorectal cancer is the third most commonly diagnosed cancer in males and the second most in females, with an estimated 1.4 million new cases and 693,900 deaths occurring in 2012 [1]. The association between the tumor location and the prognosis has been explored in the metastatic setting [6,7,8]. These studies focused on the treatment effect or response to chemotherapy, especially in terms of molecular targeting agents. Retrospective studies have many limitations, such as unspecified indications of surgery, heterogeneous populations, and heterogeneous treatments To overcome these limitations associated with retrospective studies, we focused on cases that had been enrolled in large, randomized clinical trials of adjuvant chemotherapy by pooling individual patients’ data [9,10,11]
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