Trends in lymph node excision and impact of positive lymph node ratio in patients with colectomy for primary colon adenocarcinoma: Population based study 1988 to 2011

Abstract

BackgroundStudies suggest increased lymph node excision in patients with colon cancer portends improved survival. Guidelines recommend excising 12 or more lymph nodes during colectomy. There is an inverse correlation between the positive lymph node ratio and survival in patients of these patients. ObjectiveWe sought to determine whether colon cancer patients have adequate lymph node excision and whether positive lymph node ratio can be used as a guiding factor for their treatment plan. DesignRetrospective, Observational. SettingsUnited States, 1988–2011. PatientsUtilizing the Surveillance, Epidemiology, and End Results registry, we identified 318,323 patients who underwent colectomy for colonic adenocarcinoma. Patients were stratified by age, tumor stage, tumor grade, race, ratio of positive nodes, and year of diagnosis. Main outcome measuresWe determined the percentage of patients undergoing lymph node excision and mean number of nodes excised by year of diagnosis. In patients with adequate lymph node excision, positive lymph node ratio versus overall and cancer-specific survival was evaluated. Results302,620 patients (95%) had at least 1 lymph node excised and 164,583 patients (52%) had 12 or more lymph nodes excised. This correlates to an increase from approximately 30% in 1988 to 80% by 2011. The mean number of nodes excised doubled from 9 to 18 in the entire cohort over the timeframe studied. On multivariate analysis, the 4 year cluster of diagnosis was the largest predictor of receipt of adequate lymph node excision with a 1.68 times higher odds per 4-year increase from 1988 (95% CI 1.67–1.69, p < 0.001). Higher positive lymph node ratio correlated with significantly worse overall and cancer-specific survival in those who had 12 or more lymph nodes excised. At a positive lymph node ratio of 0.16, there is a 15.7% increased rate of cancer specific mortality. ConclusionsDespite improvement in the performance of lymph node excision in patients undergoing colectomy for colon adenocarcinoma since 1988, only 80% of patients had adequate lymph node excision in 2011. Increasing positive lymph node ratio predicts significantly worse cancer-specific survival and a ratio of 0.16 may be considered an indication for a more aggressive therapeutic plan. CategoryColorectal/Anal Neoplasia.