Accelerated partial breast irradiation: initial experience with the Intrabeam System.

Failure after breast conserving surgery (BCS) and total breast irradiation usually occurs at the site of the original tumor. This has caused an increased interest in accelerated partial breast irradiation (APBI), because if radiation is delivered directly to the tumor bed there should be better local control. Patients greater than age 50 with core biopsy confirmed invasive ductal carcinoma were enrolled. They had preoperative ultrasound defining margins of less than 3.5 cm. Intraoperative ultrasound was also performed in an effort to ensure good surgical margins. After excision of the tumor, intraoperative radiotherapy (IORT) with the Intrabeam System was delivered to the tumor bed. The procedure has been performed on 67 patients. Sixty-one patients had it with the original surgery, while 6 had the procedure after re-exploration of the segmental mastectomy site. Because of the final pathology (surgical margins, tumor biology, and nodal status) 4 patients later had total mastectomy and 11 received total breast irradiation. When total breast irradiation is done the IORT serves as the radiation boost. The cosmetic results have been good to excellent, and there have been no serious surgical or radiation complications. To date there have been no local failures. IORT with the Intrabeam System is feasible, user friendly, versatile, with few complications, good cosmetic results, and great patient acceptance. It is practical and excellent for breast IORT in the community setting.