Investigation of the Effect of Tumor Location in Patients with Stage III Colon Cancer Receiving Adjuvant Oxaliplatine-Based Adjuvant Chemotherapy

Left-sided (LCC) and right-sided (RCC) colon cancers have different prognostic and predictive features in metastatic colon cancers, however there is insufficent data about tumor location in stage III disease. The aim of this study is to investigate the effect of tumor location on prognosis in patients with stage III colon cancer. From 2006 to 2012, medical records of 215 patients who underwent primary surgery and received adjuvant oxaliplatin based chemotherapy at 5 referral centers were collected, retrospectively. Disease-free survival (DFS) and overall survival were analysed using Kaplan-Meier and log-rank tests, and prognostic facrtors were identified by Cox regression methods. Clinicopathological characteristics of patients were similar between patients with right-and left-sided colon cancers. The 3-year DFS rate was similar (88% vs 78%, p= 0.07) but the RCC was significantly associated with a shorter 3-year OS than LCC (76% vs 87%, p= 0.03). The 3-year median OS was 125.8 months for all patients groups, 92.2 (+/- 5.81) months for the RCCs and 132.2 (+/- 5.52) months for the LCCs (p= 0.037). Multivariate analysis showed that stage (HR:0.32, p= 0.042 for OS) and venous invasion (HR: 0.28, p= 0.002 for OS) were the independent prognostic factors. Although there was no DFS difference between RCCs and LCCs, poorer survival of RCC indicated that the prognosis of RCC worsened after transitioning to the metastatic stage. Tumor location may be a prognostic factor in metastatic colon cancer but not in stage III disase.