Clinical characteristics of synchronous colorectal cancer are different according to tumour location

AIMS: The purpose of this study was to investigate the clinical characteristics of synchronous cancer patients, with particular attention given to variations in tumour location. METHODS: A retrospective evaluation of 249 synchronous cancer cases out of 3061 consecutive colorectal cancer patients. RESULTS: Multivariate analysis of risk factors for synchronous cancer according to tumour location revealed that male gender was a significant risk for synchronous lesions in the left colon only (odds ratio=2.05, 95% confidence interval 1.34-3.13). Meanwhile, aging was a risk factor for synchronous cancer in the right colon only (odds ratio=1.05, 95% confidence interval 1.02-1.08), and in both sides of the colon (odds ratio=1.03, 95% confidence interval 1.01-1.05), but not in the left colon only (odds ratio=0.98, 95% confidence interval 0.97-1.00). In addition, patients with synchronous lesions in the right colon only tended to have adenomas in the right colon, while those with synchronous lesions in the left colon only tended to have adenomas in the left colon (each P value <0.05). CONCLUSION: The risk factors and status of concurrent adenomas of synchronous cancer cases varied according to tumour location, suggesting that the colonic site susceptible to neoplasia varies according to patient characteristics.