Accelerated Hypofractionated Adjuvant Whole Breast Radiotherapy with Concomitant Photon Boost after Conserving Surgery for Early Stage Breast Cancer: A Prospective Evaluation on 463 Patients

The current standard therapeutic option for early stage breast cancer (EBC) employs a multimodality treatment approach including conservative surgery, radiotherapy, chemotherapy, and hormone therapy. The most common adjuvant radiotherapeutic strategy consists of external beam radiation therapy (EBRT) delivered to the whole breast using 1.8-2 Gy fractions given five times a week, up to a total dose of 45-50 Gy over a period of 5 weeks. In recent years, altered schedules employing larger dose per fraction delivered in fewer treatment sessions over a shorter overall treatment time began to be explored. We herein present clinical data on accelerated hypofractionated adjuvant whole-breast radiotherapy delivered on a daily basis for a total treatment time of 20 fractions. Between February 2005 and June 2009, a total of 463 patients underwent hypofractionated accelerated adjuvant radiation after conservative surgery for early breast cancer (pathological stage pTis, pT1 or pT2, pN0-N1). The basic course of radiotherapy consisted of 45 Gy, to the whole breast in 20 fractions with 2.25 Gy/fraction; an additional daily boost dose of 0.25 Gy was concomitantly delivered, to the lumpectomy cavity, for an additional total dose of 5 Gy. The cumulative nominal dose was 50 Gy. At follow-up, patients were examined at 3 and 6 months after the end of radiotherapy and twice a year afterward. Toxicity was scored according to the Common Terminology Criteria for Adverse Events, using the Radiation Therapy Oncology Group /European Organization for Research and Treatment of Cancer toxicity scale. Cosmetic results were assessed in agreement with the Harvard criteria. All the 463 patients treated with the accelerated hypofractionated adjuvant whole-breast radiotherapy schedule achieved at least 6 months' follow-up and subsequently were considered for the present analysis. With a median follow-up of 27 months, 5-year DFS is 93.1%. Only three patients experienced disease recurrence: two of them with an axillary nodal relapse; one patient with systemic spread. No local relapse occurred. No major toxicities (grade 3 or more) were detected during follow-up. Only 2% of the patients experienced grade 3 skin toxicity at the very end of the radiotherapy course. Cosmetic result was assessed and scored at 6 months, 1 year, 2 years: 100% of patients showed excellent or good cosmetic result. The explored accelerated hypofractionated adjuvant radiotherapeutic approach for early breast cancer with concomitant photon boost seems to be feasible providing consistent clinical results with excellent short-to-medium-term toxicity profile.