T1 Stage Breast Cancer: Adjuvant Hypofractionated Conformal Radiation Therapy to Tumor Bed in Selected Postmenopausal Breast Cancer Patients—Pilot Feasibility Study

Abstract
To explore the feasibility of a short course of hypofractionated conformal radiation therapy to the tumor bed as part of a breast preservation protocol in postmenopausal patients with nonpalpable pT1N0 stage breast cancer. The tumor bed was imaged at computed tomography (CT) in the prone position on a dedicated table. The same table and position were used for treatment with a 4-MV linear accelerator. The planning target volume was the tumor bed plus a 1-2-cm margin defined at postmastectomy CT. A regimen of five fractions was tested in this pilot dose study. Cosmesis was assessed by patients and physicians before treatment and 36 months after treatment. Ten consecutive patients who were eligible for the study were assigned to one of three dose-per-fraction regimens; nine were treatable with the proposed technique on the basis of CT findings. Patients received five fractions over 10 days (total dose range, 25-30 Gy): Three received 5.0 Gy per fraction; four, 5.5 Gy; and two, 6.0 Gy. At minimum follow-up of 36 months (range, 36-53 months), all patients were alive and disease free with good to excellent cosmesis. Hypofractionated conformal breast radiation therapy is feasible. Further studies are warranted.