Number of lymph nodes examined and associated clinicopathologic factors in colorectal carcinoma.

CONTEXT Nodal metastasis is one of the most important prognostic factors in colorectal carcinoma. The number of lymph nodes recovered and examined in resection specimens has been recently shown to be critical for proper staging and is associated with survival. OBJECTIVE To assess the clinicopathologic factors that may be associated with the number of lymph nodes harvested from surgical resections. DESIGN Clinicopathologic factors of 434 consecutive cases of colorectal cancers treated by surgical resection from a single tertiary medical center were retrospectively reviewed and correlated with number of lymph nodes recovered. RESULTS Our data show that patient age, tumor location, and length of resected bowel segment were associated with number of lymph nodes harvested in surgical resections of colorectal cancer. The average number of lymph nodes was 18.2 and 17.8 for patients younger than 50 years and aged 50 through 60 years, respectively, whereas it was 14.4, 15.1, and 14.9 for patients aged 61 through 70 years, 71 through 80 years, and 80 years and older, respectively. More lymph nodes were present in resection specimens of cecum/ascending colon and descending colon cancers than in those of transverse colon, sigmoid colon, and rectal cancers. There was a linear increase in number of lymph nodes examined with increasing length of bowel resection specimens. In multivariate regression analysis, the factors that remained independent predictors of removal of 12 or more lymph nodes from resection specimens were tumor location and length of resected bowel segment. CONCLUSIONS The number of lymph nodes obtained in resection specimens for colorectal cancer was significantly associated with the length of resected segments of bowel, patient age, and location of the tumor.