RESUMEN
PURPOSE: Three-dimensional conformal accelerated partial breast irradiation (APBI) is a treatment option for well selected women with breast cancer, despite reports of adverse cosmetic outcome with this technique. Dose-volume relationships may be responsible for this poor cosmesis. We aimed to determine the feasibility of limiting the exposure of nontarget breast tissue to radiation through smaller planning target volumes achieved through daily image guidance and 4-dimensional computed tomography simulation. METHODS AND MATERIALS: Eligibility criteria included the following: women, age ≥50 years, Karnofsky performance status score ≥70, stage 0 and I breast cancer treated with breast-conserving surgery, margins clear by ≥2 mm, pathologic tumor size ≤2 cm, and 4-dimensional computed tomography with planning target volumes of 0.2 cm rather than the standard 1.0 cm. A dose of 3850 cGy was prescribed in 10 fractions. The study was considered successful if ≥50% of enrollees met dosimetric constraints on the breast (V50 < 45% and V100 < 23.5%). RESULTS: The study achieved its primary endpoint of feasibility of reducing the nontarget breast dose with a breast median of V50 = 31% and V100 = 11%. There were no recurrences and no toxicity grade >3. At baseline, fair/poor cosmesis was low (2.2%). By year 3, adverse cosmesis post-APBI had increased by 13.2% (to 15.4%). Patient decisional satisfaction was reached completely in 84.2% of patients. CONCLUSIONS: This study demonstrated that with 4-dimensional simulated APBI that uses stringent dosimetric constraints and image guidance radiation therapy, it is possible to obtain acceptable cosmetic outcomes. We report no locoregional recurrences in 3 years and no toxicity grade >3. The observed decline in cosmesis was acceptable compared with that of prior published studies, and patient satisfaction with APBI was excellent.