Objective To examine clinicopathologic characteristics and survival differences of colon cancer patients by different primary locations.

Methods We retrospectively analyzed the medical records of 1088 colon cancer patients. Kaplan-Meier curves were generated for colon subsite location, and survival curves were compared with the Log rank test. Cox proportional hazards regression models were used for multivariate survival analyses.

Results Patients with ascending colon cancer were the oldest(mean age: 61.1±12.3 years) and predominantly were female (47%). Tumor diameters in ascending and transverse colon cancer groups (5.9±2.2cm and 5.8±2.4cm) were significantly larger than those in descending and sigmoid colon cancer groups(4.4±1.8cm and 4.6±1.7cm) (P=0.000). A larger proportion of sigmoid cancer group (9.9%) presented as stage Ⅰ compared with ascending colon cancer group (3.8%) (P=0.001). Ascending and transverse colon cancer groups were associated with a larger proportion of poorly-differentiated and undifferentiated adenocarcinoma, mucinous adenocarcinoma and vascular invasion than descending and sigmoid colon cancer groups, with significant difference. The five-year overall survival of ascending, transverse, descending and sigmoid colon cancer groups were 71.4%, 75.4%, 73.5% and 79.7% respectively (P=0.000). Multivariate adjusted overall survival analyses showed sigmoid colon cancer group had decreased risk of death compared with ascending colon cancer group (HR=0.68, 95%CI:0.50-0.91). In stage Ⅳ disease, sigmoid colon cancer group had the most favorable outcome (HR=0.54, 95%CI:0.32-0.90).

Conclusion Colon cancer patients with different primary locations have different clinical data and survival, and those with stage Ⅳ sigmoid colon cancer have the best prognosis.