Survival of lymph node-negative breast cancer patients in relation to number of lymph nodes examined.

Abstract

To assess the relationship between number of lymph nodes examined and survival of patients diagnosed with node-negative localized breast cancer using a large sample of patients from population-based cancer registries in the United States. Conflicting results have been reported from studies on the relationship between number of lymph nodes examined and survival of patients diagnosed with node-negative localized breast cancer. The study included 69,543 patients diagnosed in 1988-97 with localized invasive node-negative breast cancer reported to nine population-based registries in the U.S. National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) Program of population-based cancer registries. Hazard ratios for groups defined by number of nodes examined were analyzed in Cox proportional hazards regression models that included age, tumor size and grade, race/ethnicity, and other variables. A significantly higher risk of death from breast cancer was found among patients with 0, 1 to 3, or 4 to 10 nodes examined than with 20-plus nodes examined, even among patients with tumors 2 cm or smaller. Future studies of survival of node-negative patients, by number of nodes examined, should include information on comorbidity and treatment.