Twelve-year clinical outcomes and patterns of failure with accelerated partial breast irradiation versus whole-breast irradiation: results of a matched-pair analysis.

BACKGROUND AND PURPOSE: To compare 12-year outcomes of accelerated partial breast irradiation (APBI) versus whole-breast irradiation (WBI) in patients treated with breast conservation.

MATERIALS AND METHODS: A matched-pair analysis was performed using 199 patients receiving WBI and 199 patients receiving interstitial APBI. Match criteria included tumor size, age, nodal status, ER status, and the use of adjuvant hormonal therapy. Patterns of failure and efficacy of salvage treatments were examined.

RESULTS: No differences were seen in the 12-year rates of local recurrence (3.8% vs. 5.0%, p=0.40), regional recurrence (0% vs. 1.1%, p=0.15), disease free survival (DFS) (87% vs. 91%, p=0.30), cause-specific survival (CSS) (93% vs. 95%, p=0.28), or overall survival (OS) (78% vs. 71%, p=0.06) between the WBI and APBI groups, respectively. The rate of distant metastases was lower in the APBI group (10.1% vs. 4.5%, p=.05). Following LR, no difference in outcome was seen between the two groups with 5year post-LR rates of DFS (80% vs. 86%, p=0.55), CSS (88% vs. 75%, p=0.77), and OS (88% vs. 75%, p=0.77), respectively.

CONCLUSIONS: With 12-year follow-up, APBI produced outcomes equivalent to WBI. Following LR, patients treated with APBI also had similar failure patterns to those managed with WBI.