Strut-based accelerated partial breast irradiation: Report of treatment results for 250 consecutive patients at...

This registry trial studied the long-term outcomes of women receiving accelerated partial breast irradiation (APBI) using strut-based applicators and reports on the local control, toxicity, and survival for the first 250 patients treated with this device.

Patients were treated using the strut-based brachytherapy device with conventional dose and fractionation of 34 Gy in 10 twice-daily fractions. Planning goals for the planning target volume were V₉₀ > 90%, V₁₅₀ < 50 cc, and V₂₀₀ < 20 cc. Toxicity was graded based on the Common Terminology Criteria for Adverse Events v3.0. Recurrence rates were also calculated.

Median followup was 59.5 months for the 250 patients. Grade 2 or higher adverse events at any time for hyperpigmentation, induration, erythema, telangiectasia, breast pain, seroma, and fat necrosis were 0.4%, 3.0%, 3.0%, 3.0%, 3.9%, 4.8%, and 1.3%, respectively. The median V₉₀ was 97%, V₉₅ was 95.1%, V₁₅₀ was 28.7 cc, and V₂₀₀ was 14.2 cc. For those patients with a less than a 5-mm or 3-mm-skin bridge, the median skin max doses were 272 and 289 cGy, respectively. The 4-year actuarial recurrence rates for true recurrence/marginal miss and ipsilateral breast tumor recurrence were 2.3% and 3.6%, respectively. The 4-year actuarial rates for overall survival, cause-specific survival, and disease-free survival were 97%, 98%, and 92%, respectively.

The strut-based applicator was designed to simplify APBI compared to interstitial brachytherapy. This report confirms excellent tumor control and survival with low toxicity and supports the evidence that brachytherapy has less normal tissue toxicity than APBI with external beam irradiation.