Colorectal Research Center, Faghihi Hospital, Shiraz University of Medical Sciences, Shiraz, IR Iran
Student Research Committee, Namazi Hospital, Shiraz University of Medical Sciences, Shiraz, IR Iran
Biostatistics Department, School of Medicine, Shiraz University of Medical Sciences, Shiraz, IR Iran
Background The extent of lymph node involvement is the most significant prognostic indicator in resected locoregional colorectal cancer. Objectives This study aimed to investigate the prognostic value of total lymph nodes identified and ratio of lymph nodes in resected colorectal cancer. Patients and Methods Two hundred seventy five patients with histologically proven resected locoregional invasive colorectal adenocarcinoma from 2003 to 2011 were included. All patients were treated with standard surgical resection for their colorectal cancer. Patients with incomplete data, or unresectable tumors or distant metastases were excluded from the study. All potential prognostic variables were evaluated for their impact on the local control, disease-free, and overall survival rates. Results Of the 275 patients, 162 were men and 113 were women with a median age of 54 (range 23-84) years. The mean total lymph nodes were significantly higher in colon cancer than rectal cancer (11 versus 7.5, P = 0.001). In node positive (stage III) patients, the mean lymph nodes ratio was 0.5 for rectal cancers and 0.37 for colon cancers respectively showing a nonsignificant (P = 0.05) trend toward higher lymph nodes ratio in rectal cancer patients. In univariate analysis, the mean total number of lymph node identified was a prognostic factor for 5-year disease free (P = 0.04) and overall survival (P = 0.02) rates. In node positive patients, lymph nodes ratio was a prognostic factor for 5-year local control (P = 0.04), disease free survival (P = 0.01), and overall survival (P = 0.01) rates. On multivariate analysis, advanced primary tumor stage, rectal primary site and the presence of perineural invasion were independent adverse prognostic factors for overall survival. Conclusions Total lymph nodes identified and ratio of lymph nodes are associated with oncological outcomes outcomes in patients with colorectal cancer.