The prognosis of T3N0 colon cancer is dependent on the number of lymph nodes examined

Background: T3N0 colon cancer is the target of many adjuvant studies. Very few studies have examined the relationship of the number of lymph nodes examined to the prognosis of this stage. We examined data from the National Cancer Data Base (NCDB) to determine whether the number of examined lymph nodes is prognostic for T3N0 colon cancer. Methods: A total of 35,787 prospectively collected cases of T3N0 colon cancer that were surgically treated and pathologically reported from 1985 to 1991 to the NCDB as T3N0M0 were analyzed. Results: The 5-year relative survival rate for T3N0M0 colon cancer varied from 64% if 1 or 2 lymph nodes were examined to 86% if >25 lymph nodes were examined. Three strata of lymph nodes (1-7, 8-12, and greater than or equal to13) distinguished significantly different observed 5-year survival rates. Conclusions: These results demonstrate that the prognosis of T3N0 colon cancer is dependent on the number of lymph nodes examined. A minimum of 13 lymph nodes should be examined to label a T3 colon cancer as node negative. These data suggest that adjuvant trials for T3N0 colon cancer should stratify according to the number of lymph nodes examined.