The influence of the number of retrieved lymph nodes on staging and survival in patients with stage II and III rectal cancer undergoing tumor-specific mesorectal excision

OBJECTIVE: This study was designed to determine whether the number of lymph nodes retrieved influence staging and survival in patients with stage II and III rectal cancer that undergo tumor-specific mesorectal excision. SUMMARY BACKGROUND DATA: The prognostic impact of the retrieved nodes has been emphasized in patients with colorectal cancer, but few studies have focused on patients with rectal cancer. METHODS: A total of 900 patients who underwent tumor-specific mesorectal excision with curative intent and adjuvant chemoradiation therapy for stage II and III rectal cancer from January 1989 to December 2006 were analyzed. RESULTS: Cancer-specific survival (CSS) of stage II patients with less than 15 nodes (25th percentile) was not different from stage III patients, but CSS was better in stage II patients with more than 15 nodes. When using cutoff values of the 25th and 50th percentiles (22 and 31 nodes), recurrence-free survival (RFS) was statistically different among subgroups of stage II and III patients. In multivariate analysis, stage II disease with less than 15 nodes retrieved was an adverse factor for CSS and RFS. In Kaplan-Meier survival analysis, using cutoff values, the difference for CSS was not significant with 22 and more nodes and the difference for RFS was not observed with 23 and more nodes. CONCLUSIONS: The number of lymph nodes retrieved is closely associated with survival and recurrence in patients with stage II rectal cancer and, for more accurate prognostic stratification, at least 22 and 23 nodes seem to be necessary, respectively, for CSS and for RFS.ope