Outcomes of Clinically Node-Negative Breast Cancer Without Axillary Dissection: Can Preserved Axilla Be Safely Treated With Radiation After a Positive Sentinel Node Biopsy?

Abstract

PurposeWe analyzed whether axillary nodal irradiation could control clinically node-negative disease, including those patients with a positive sentinel lymph node biopsy (SLNB), most of whom received regional nodal irradiation. We also evaluated toxicity profiles that resulted from nodal irradiation. Patients and MethodsFrom 1988 to 2011, 2107 patients with cT1-T2N0M0 breast cancer underwent breast conservation therapy in the absence of axillary dissection: nx group (n = 1548), without any axillary surgery; the sn− group (n = 518), with a negative SLNB; and sn+ group (n = 104), with a positive SLNB. ResultsThe median follow-up times were 88, 56, and 55 months for the nx, sn−, and sn+ groups, respectively. The nx group had more risk factors than did the other 2 groups in terms of age, grade, or T stage. Ninety-eight percent of the sn−group received only tangent irradiation, and 100% and 83% of the sn+ and nx group, respectively, received additional regional nodal irradiation. The 5-year cumulative incidences of axillary failure and regional nodal failure were 34, 3, and 0 (2.7%, 0.7%, and 0%; P = .02, log-rank test) and 57, 4, and 0 (4.4, 1%, and 0; P = .04), respectively. Overall survival rates in 5 years were 96.4%, 98.9%, and 97.6% (P = .03), respectively. Symptomatic but transient radiation pneumonitis developed in 31, 16, and 6 (2.0%, 3.1%, and 5.7%). Mild arm edema was observed in 1, 4, and 0 (0.06%, 0.8%, and 0%) in the nx, sn−, sn+ groups, respectively. ConclusionsTreatment without axillary dissection showed excellent outcomes with negligible toxicity for patients with clinically node negative, including those with a positive SLNB. Regional nodal irradiation after a positive SLNB is a reasonable alternative to axillary dissection.