Axillary lymph node failure in patients treated with accelerated partial breast irradiation.

BACKGROUND: Data on the risk of axillary failure (AF) after accelerated partial breast irradiation (APBI) are limited. In this study, the authors determined the rate of AF and regional lymph node failure (RNF) in patients who received various forms of APBI and identified factors that were associated with its occurrence.

METHODS: In total, 534 patients with early stage breast cancer were treated at William Beaumont Hospital with APBI, including 466 patients (87%) with invasive breast cancer and 68 patients (13%) with ductal carcinoma in situ. Clinical variables (patient age, tumor location), pathologic variables (tumor size, grade, estrogen receptor status, margin status, lymph node status), and treatment-related variables (receipt of hormone and systemic chemotherapy) were analyzed to determine which factors were associated with AF and RNF. The median length of follow-up was 63 months (range, 1-201 months).

RESULTS: The 5-year actuarial AF rate was 0.19%. Three patients (0.56%) developed RNF (all patients initially had invasive breast cancer) with a 5-year actuarial rate of 0.37%. Two of the regional recurrences were in the supraclavicular fossa, and 1 was in the axilla. No variables were associated with AF. However, patient numbers were very small. The median survival after RNF was 0.8 years (range, 0.3-1.7 years), and 2 of the 3 patients died of disease.

CONCLUSIONS: The rate of AF and RNF after APBI was low and appeared to be similar to the rate observed with whole-breast irradiation. No variables were associated with a higher rate of AF after APBI.