índice ganglionar y número de linfonodos metastásicos como factores pronósticos en cáncer de colon

background: the lymph node ratio in malignant tumors corresponds to the ratio between the number of involved lymph nodes and the number of examined lymph nodes. this ratio may be a good prognostic index in stage iii colon cancer. aim: to compare the lymph node ratio with the absolute number of positive lymph nodes as prognostic factors in stage iii colon cancer. material and methods: analysis of 115 patients aged 25 to 91 years (63% women) with a stage iii colon cancer operated between 1991 and 2007. survival according to the absolute number of positive lymph nodes and the lymph node index was calculated. the area under receiver operating characteristic (roc) curves obtained after a cox regression analysis of survival, was used to analyze the prognostic value of each parameter. results: lymph node involvement was classified as t2 in three, t3 in 93 and t4 in 19 patients. the mean number of positive lymph nodes was 3.4 (range 1 to 34) and the mean lymph node index was 0.237 ± 0.197 (range 0.031-0.882). seventy four percent of patients had one to three positive lymph nodes and 24% had more than three. during a mean follow up of 67 months (range 5-216), 29 patients died. in survival analysis, the area under the roc curve for the number of involved lymph nodes (0.703, 95 confidence intervals (ci) 0.58-0.82) was slightly better than the area for lymph node index (0.69, 95% ci 0.57-0.81). using a dichotomy analysis, a lymph node index over 0.31 had a higher discriminating value for survival (odds ratio (or) 19.96 91% ci 1.51-253.6) than the presence of 12 or more involved lymph nodes (or 2.55 95% ci 0.86-7.55). conclusions: the lymph node index and the absolute number of involved lymph nodes are prognostic factors in stage iii colon cancer.