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

We analyzed whether axillary nodal irradiation could safely control early-stage breast cancer, including those patients with a positive sentinel lymph node biopsy. Axillary or regional nodal irradiation without axillary nodal dissection showed excellent outcomes, with negligible toxicity for patients with clinically node-negative disease. Regional nodal irradiation after a positive sentinel lymph node is a reasonable alternative to axillary dissection. Purpose: We 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 Methods: From 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. Results: The 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 sngroup 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 ,s n groups, respectively. Conclusions: Treatment 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.