Effect of axillary lymphadenectomy on breast carcinoma survival

Purpose. To determine the effect of axillary lymphadenectomy on breast carcinoma survival, and to determine racial and age differences in the extent of axillary lymphadenectomy. Methods. Cases were 257,157 women diagnosed with breast carcinoma in the Surveillance, Epidemiology and End Results program from 1988 through 2000. Variables included number of lymph nodes removed, number of positive lymph nodes, ratio of positive nodes to number of nodes removed, use of radiation therapy, surgery (breast conserving surgery versus mastectomy), stage, age, race, and hormone receptor status. Correlation statistics were used to determine associations between survival and lymph node variables for all cases and when stratified by stage. Kaplan-Meier survival analyses were used to compare survival by lymph node categories overall and stratified by stage. Cox regression analyses were used to determine factors associated with survival. Results. Older women were significantly less likely to have lymph nodes examined and lymph node involvement compared to younger women, and black women were significantly less likely to have lymph nodes examined, but were significantly more likely to have lymph node involvement compared to white women. Risk of death was significantly reduced for cases who had lymphadenectomy compared to those who did not. For cases diagnosed at stage IIA or higher, risk of death increased significantly with increased number of positive nodes and increased ratio of positive to total nodes removed. Conclusions. Improved survival in node negative cases of breast carcinoma may be due to removal of undetected micrometastases. Women diagnosed at more advanced stages as well as black women may also benefit from more extensive lymphadenectomy.