Survival of women after breast conserving surgery for early stage breast cancer.

BACKGROUND: Increasing numbers of older women with breast cancer are receiving breast-conserving surgery (BCS). However, substantial numbers of them are not receiving either axillary dissection or adjuvant irradiation.

OBJECTIVE: To determine whether failure to perform axillary dissection or irradiation is associated with decreased survival in women with early-stage breast cancer.

METHOD: We studied 26,290 women aged > or = 25 in 1988-1993 from the surveillance, epidemiology, and end results (SEER) data and 5,328 women aged > or = 65 in 1991-1993 from SEER-Medicare linked data, who had early-stage breast cancer and received BCS.

RESULTS: Twenty seven percent of women aged > or = 25 receiving BCS did not receive axillary dissection, most of whom (74%) were age > or = 65. Women receiving BCS with axillary dissection had lower 7-year breast cancer-specific mortality than did those without dissection (hazard ratio = 0.53, 95% confidence interval: 0.44-0.63). We found an interaction between receipt of axillary dissection and radiotherapy on survival of older women after BCS. Women who received either axillary dissection or radiotherapy experienced similar survivals to those who received both axillary dissection and radiation, while women who received neither treatment experienced poorer survival (hazard ratio = 1.76, 1.23-2.52), after controlling for demographics, tumor size and comorbidity.

CONCLUSIONS: Women who receive neither axillary dissection nor radiation therapy after BCS experience an increased risk of death from breast cancer. The lack of improvement in the past two decades in survival of older women with breast cancer may be explained in part by the increasing use of treatments that do not address potential tumor in axillary nodes.