Five-year results of whole breast intensity modulated radiation therapy for the treatment of early stage breast cancer: the Fox Chase Cancer Center experience

Abstract

Purpose: To report the 5-year outcomes using whole-breast intensity-modulated radiation therapy (IMRT) for the treatment of early-stage-breast cancer at the Fox Chase Cancer Center.

Methods and materials: A total of 946 women with early-stage breast cancer (stage 0, I, or II) were treated with IMRT after surgery with or without systemic therapy from 2003-2010. Whole-breast radiation was delivered via an IMRT technique with a median whole-breast radiation dose of 46 Gy and median tumor bed boost of 14 Gy. Endpoints included local-regional recurrence, cosmesis, and late complications.

Results: With a median follow-up of 31 months (range, 1-97 months), there were 12 ipsilateral breast tumor recurrences (IBTR) and one locoregional recurrence. The 5-year actuarial IBTR and locoregional recurrence rates were 2.0% and 2.4%. Physician-reported cosmestic outcomes were available for 645 patients: 63% were considered "excellent", 33% "good", and <1.5% "fair/poor". For physician-reported cosmesis, boost doses≥16 Gy, breast size>900 cc, or boost volumes>34 cc were significantly associated with a "fair/poor" cosmetic outcome. Fibrosis, edema, erythema, and telangectasia were also associated with "fair/poor" physician-reported cosmesis; erythema and telangectasia remained significant on multivariate analysis. Patient-reported cosmesis was available for 548 patients, and 33%, 50%, and 17% of patients reported "excellent", "good", and "fair/poor" cosmesis, respectively. The use of a boost and increased boost volume: breast volume ratio were significantly associated with "fair/poor" outcomes. No parameter for patient-reported cosmesis was significant on multivariate analysis. The chances of experiencing a treatment related effect was significantly associated with a boost dose≥16 Gy, receipt of chemotherapy and endocrine therapy, large breast size, and electron boost energy.

Conclusions: Whole-breast IMRT is associated with very low rates of local recurrence at 5 years, 83%-98% "good/excellent" cosmetic outcomes, and minimal chronic toxicity, including late fibrosis.