Preliminary results of a prospective trial of image-guided 3D conformal accelerated partial breast irradiation (APBI).
125 Background: External beam APBI is noninvasive and may offer better coverage of tumor sites in proximity to skin or chest wall than brachytherapy. To improve conformality and accuracy of treatment, we conducted a prospective IRB-approved clinical trial of APBI with implanted gold markers for image guidance. Cosmetic assessments through patient and physician questionnaires were collected. Adverse events were graded according to Common Terminology Criteria for Adverse Events v3.0. This is our preliminary report on toxicity and cosmetic outcomes. Methods: Thirty-four pts were enrolled from 12/06 to 4/10. Eligibility criteria included age > 40, unifocal disease, ductal histology, tumor ≤ 3 cm, surgical margin ≥ 2 mm, and planning target volume: breast volume ratio < 0.2. Vascular invasion, positive axillary nodes, high-grade ductal carcinoma in situ, and extensive intraductal component were excluded. Three gold fiducials were sutured into the operative site at the time of partial mastectomy. The clinical target volume comprised the surgical cavity including all surgical clips and gold fiducials + 10-15 mm. Prescribed dose was 3.85 Gy b.i.d. to 38.5 Gy, using 4–5 non-coplanar beams. Special breathing technique and image guidance with electronic portal imaging were used. Results: Median follow-up is 18 months (range 7-47 months). Most pts had mild acute reactions with only 6% grade 2 erythema. Late toxicities include hyperpigmentation (71% grade 1), fibrosis (26% grade 1, 32% grade 2), skin dimpling or indentation (38% grade 1, 3% grade 2), telangiectasias (12% grade 1), rib fractures in the treatment area (3% grade 2). The only grade 3 toxicity was a seroma requiring surgical excision in one pt. Cosmesis was rated by the pt versus (v.) physician as excellent/good in 85% v. 94%, 80% v. 90%, and 84% v. 85% of the pts at prior to treatment, 6 months, and one year respectively. Ninety-one percent of patients were “totally satisfied with the treatment and results.” No breast recurrences have been observed. Conclusions: Image-guided APBI is well-tolerated, with high patient satisfaction. Early cosmesis results, as assessed by both pts and physicians, are comparable to whole-breast radiotherapy.