Accelerated Partial Breast Irradiation With 3D-CRT and IMRT

It is a sequential phase II trial. Eligible patients after breast conserving surgery (BCS) are treated with accelerated partial breast irradiation (APBI) using three-dimensional conformal radiotherapy (3D-CRT) for the first 45 patients or intensity modulated radiotherapy (IMRT) for the second 45 patients. Primary end-point of the study: late radiation side-effects at 5 years. Early stopping criteria: Not used as primary end-point is late side-effects. Interim analysis: Not planned Secondary end-points: cosmetic results, quality of life, local recurrence-free survival, regional recurrence free survival, distant metastasis free survival, relapse free survival, overall survival, cancer specific survival. Null-hypothesis for primary end-point: The incidence of severe (\>G2) late radiation side-effects after APBI using 3D-CRT or IMRT will not exceed 10%. Stratification: * by treatment delivery: 3D-CRT - first 45 patients; IMRT - second 45 patients * by bra capsize: Capsize A-B; C; and D-D+ Treatment intervention: 9 x 4.1 Gy APBI using 3D-CRT (first 45 patients) or IMRT (second 45 patients) delivered within 5 days, using twice-a-day fractionation. Clinical target volume (CTV) and Planning target volume (PTV) definition: CTV = excision cavity + 20 mm minus the actual pathological surgical margin in mm PTV = CTV + 5 mm in each direction Follow-up: * ECOG PS, physical examination (inspection and palpation), registration of side-effects (RTOG (Radiation Therapy Oncology Group) EORTC (European Organization for Research and Treatment of Cancer)) early and late radiation morbidity scoring scheme) and cosmetic results (using the Harvard scale) : 7-14 days after RT, than in every 3 months for 2 years, and every 6 months for 5 years. * Mammography: at 6, 12, 18, 24 months, and annually thereafter * Quality of life questionnaire (QLQ) (e.g. EORTC (European Organization for Research and Treatment of Cancer) QLQ-30 and Breast (BR)-23) before RT, at 7-14 days after RT, at 3, 6, and 12 months, and annually thereafter * digital photography: before treatment, at 7-14 days after treatment, and yearly thereafter