Accelerated partial breast irradiation after conservative surgery for breast cancer

Abstract

Objective: To critically review the theoretical and actual risks and benefits of accelerated partial breast irradiation (APBI) after breast-conserving surgery.

Summary background data: Because of rapid evolution of radiation therapy techniques related to brachytherapy and three-dimensional conformal radiation therapy, APBI has very recently come to the forefront as a potential local treatment option for women with breast cancer. This review aims to give an overview of the biologic rationale for APBI techniques, and benefits and limitations of APBI techniques.

Methods: The authors reviewed the currently available published world medical literature on breast-conserving surgery with and without postoperative irradiation; all studies involving partial breast irradiation, including brachytherapy, for breast cancer; and currently accruing and planned APBI trials. The focus of this review was the early results of treatment in terms of toxicity, complications, cosmesis, and local control.

Results: On average, approximately 3% of patients treated with breast-conserving surgery will have an in-breast local recurrence away from the original lumpectomy site with or without postoperative standard whole-breast irradiation. The results of phase I-II studies involving approximately 500 patients treated with APBI after breast-conserving surgery have been published. Although many of the studies have limited long-term follow-up and potential selection bias, early results suggest that toxicity, cosmesis, and local control are comparable to outcomes seen after breast-conserving surgery followed by standard whole-breast irradiation.

Conclusions: Recent advances in radiation delivery and published series of partial breast irradiation support large randomized trials comparing APBI with standard whole-breast irradiation after breast-conserving surgery.

FIGURE 1. Canadian randomized trial of accelerated-fractionation versus traditional whole breast irradiation after lumpectomy for women with lymph node-negative breast cancer.

FIGURE 2. MammoSite applicator (A) and computed tomography scan of device within breast showing the dose distribution to the surrounding tissue (B; from Edmundson et al; reprinted with permission).

FIGURE 3. Initial performance and safety trial of MammoSite breast brachytherapy device in women treated with breast conserving surgery for Invasive Ductal Carcinoma less than 2 cm (From Keisch et al; reprinted with permission).

FIGURE 4. Intraoperative radiation therapy for breast cancer using a linear accelerator at the Instituto Europe di Oncologia in Milan, Italy. A, To minimize radiation to the thoracic wall, an aluminum-lead disk is placed between the deep fascia of the breast and the pectoralis muscle prior to start of radiation therapy. B, Placement of the linear accelerator applicator with complete retraction of the skin to prevent radiation injury. Photos from Veronesi et al; reprinted with permission.

FIGURE 5. Targeted intraoperative radiation therapy at University College London. A, The applicator being placed in the tumor bed immediately after excision of the tumor. B, Photon-Radiosurgery System diagrammatic components. Photo courtesy of Dr Jayant Vaidya, University College London, United Kingdom.

FIGURE 6. Three-dimensional Conformal Breast Irradiation. A, Reconstruction of radiation beams used in treatment of a patient in prone position on dedicated computed tomography table. B, Sagittal display of planning target volume and isodose distributions. Images courtesy of Formenti et al; reprinted with permission.

FIGURE 7. Proposed National Surgical Adjuvant Breast and Bowel Project Randomized Trial Evaluating Partial Breast Irradiation after Lumpectomy for Breast Cancer