Hospital lymph node examination rates and survival after resection for colon cancer

Abstract

Context: Several studies suggest improved survival among patients in whom a higher number of nodes are examined after colectomy for colon cancer. The National Quality Forum and other organizations recently endorsed a 12-node minimum as a measure of hospital quality.

Objective: To assess whether hospitals that examine more lymph nodes after resection for colon cancer have superior late survival rates.

Design, setting, and patients: Retrospective cohort study, using the national Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database (1995-2005), of US patients undergoing colectomy for nonmetastatic colon cancer (n = 30 625). Hospitals were ranked according to the proportion of their patients in whom 12 or more lymph nodes were examined and then were sorted into 4 evenly sized groups. Late survival rates were assessed for each hospital group, adjusting for potentially confounding patient and clinician characteristics.

Main outcome measures: Hospitals' lymph node examination rates in association with cancer staging, use of adjuvant chemotherapy (indicated for patients with node-positive disease), and 5-year survival rate.

Results: Hospitals with the highest proportions of patients with examination of 12 or more lymph nodes tended to treat lower-risk patients and had substantially higher procedure volumes. After adjusting for these and other factors, there remained no statistically significant relationship between hospital lymph node examination rates and survival after surgery (adjusted hazard ratio, highest vs lowest hospital quartile, 0.95; 95% confidence interval, 0.88-1.03). Although the 4 hospital groups varied widely in the number of lymph nodes examined, they were equally likely to find node-positive tumors and had very similar overall unadjusted rates of adjuvant chemotherapy (26% vs 25%, highest vs lowest hospital quartile).

Conclusions: The number of lymph nodes hospitals examine following colectomy for colon cancer is not associated with staging, use of adjuvant chemotherapy, or patient survival. Efforts by payers and professional organizations to increase node examination rates may have limited value as a public health intervention.