Hypofractioned Radiation Therapy in the Treatment of Partial Breast: 30 Gy in Five Consecutive Fractions

Background and Purpose: Recent prospective studies have explored the partial breast irradiation (PBI) for patients with early-stage breast cancer using different technical approaches. The purpose of this study is to explore feasibility, tumor control and acute and late toxicity of a specific hypo-fractionated 3D-CRT when treating postmenopausal pa-tients with early breast cancer with partial breast irradiation, using five fractions in five consecutive days. Materials and Methods: Ten patients, aged 70 underwent breast conservative surgery for invasive breast carcinoma with a complete microscopic resection; no lymphovascular invasion was found and negative axillary node status was assessed. Metal clips were positioned in the surgical bed at the time of surgery. All of the patients provided an informed consent for breast irradiation. Seven patients received Tamoxifen. Of the ten patients, five were treated for left breast disease, and five for right breast disease. The dose fractionation schedule was 3000 cGy delivered to the isocenter in 5 fractions (600 cGy/fr) using 6 MV photons. According to the linear quadratic model and a / ratio of 4 Gy this prescription is equivalent to 50 Gy in a standard 2-Gy fractionation schedule. Patients were treated in the supine position. A comer-cial breast board was used as immobilization device in order to keep the arms of the patient raised. The clinical target volume (CTV) was drawn with a uniform 1-cm three-dimensional margin around the surgical clips. The CTV was lim-ited to 3 mm from the skin surface and 3 mm from the lung-chest wall interface. A three-dimensional margin was adde