Impact of radiation treatment parameters and adjuvant systemic therapy on cosmetic outcomes after accelerated partial breast irradiation using 3-dimensional conformal radiation therapy technique.

PURPOSE: There are concerns regarding cosmetic outcomes of 3-dimensional conformal accelerated partial breast radiation therapy (3DCRT APBI). Associations between cosmetic outcomes and treatment parameters or receipt of adjuvant systemic therapy were sought to guide 3DCRT APBI.

METHODS AND MATERIALS: An analysis of cosmetic outcomes among patients treated with 3DCRT APBI at Moffitt Cancer Center was performed. Overall cosmesis was evaluated using modified Harvard criteria and toxicity outcomes were graded using National Cancer Institute Common Terminology Criteria for Adverse Events, version 3.0. Patients were treated to 38.5 Gy in 3.85 Gy twice daily fractions per dose-volume objectives specified in the National Surgical Adjuvant Breast and Bowel B-39/Radiation Therapy Oncology Group 0413 (NSABP B-39/RTOG 0413) trial.

RESULTS: At least 1 evaluation was available for 97 treated breasts (94 women) with median follow-up of 17.2 months (range, 1-60 months). Most breasts (90.7%) had grade 1 to 2 (excellent to good) overall cosmesis. Nine breasts (9.3%) had grade 3 to 4 (fair to poor) overall cosmesis, secondary to >25% asymmetry in 5 patients, grade 3 fibrosis in 3 patients, and fat necrosis in 1 patient. Increasing percentage of ipsilateral breast volume receiving more than 50% of the prescription dose (V50%) correlated with less than excellent cosmesis (P < .001), with a threshold V50% of 40%. Telangiectasia formation (6%) correlated with increased evaluation planning target volume (P = .006) and V50% (P = .017). Grade 2+ fibrosis (18%) and grade 1+ induration (83%) were also correlated with increasing V50% (P = .006 and .002, respectively). Smaller ipsilateral breast volume correlated with worsening cosmesis (P = .048) and induration (P = .028). Two of 4 patients receiving chemotherapy developed grade 3 fibrosis (P = .004) and fair/poor cosmesis (P = .04).

CONCLUSIONS: The current analysis implies that acceptable cosmetic results are achievable with 3DCRT APBI technique by adhering to optimal radiation therapy dose-volume constraints, particularly ipsilateral breast V50%.