Long-Term Clinical Outcomes, Late Toxicities, and Cosmetic Results of Short-Course Two-Day Brachytherapy Accelerated Partial Breast Irradiation

Abstract

Hypofractionated radiotherapy is increasingly being adopted for early-stage breast cancer. To assess the long-term outcome of 2-day brachytherapy accelerated partial breast irradiation [2d-APBI], we analyzed patients so treated for clinical effectiveness, late toxicity, and cosmetic results. Between 3/2004 and 8/2007, 45 patients were treated with single-lumen applicator-based 2d-APBI [700 cGy BID x 4]. Updated thru 1/2017, an IRB-approved retrospective review was done. Selection criteria included age >40, ≤3.0 cm tumor size, ≤3 pathologically positive lymph nodes, and negative margins (per NSABP guidelines). Based upon the ASTRO Consensus Statement guidelines for APBI (2009) applied retrospectively, 15 were suitable (33%), 27 cautionary (60%), and 3 unsuitable (7%). Freedom from local recurrence (FFLR), regional recurrence (FFRR), distant metastasis (FFDM), contralateral breast cancer (CLBC), disease-free survival (DFS), cause-specific survival (CSS), and overall survival (OS) were assessed by Kaplan-Meier. Toxicities were scored using CTCAE v3.0. Cosmetic rating was scored via the Harvard criteria. Median follow-up was 9.4 years. Fourteen patients were followed ≥ 10 yrs (31%) and 17 with follow-up of 9.0 - 9.9 yrs (38%). Median age was 66 yrs (48-83 yrs) with most having T1 tumors (96%) [median size 0.6cm]; all had margins with no tumor on ink. A minority (4%) had positive regional nodes. ER positivity was found in 73%. Endocrine therapy was received by 61%, while 18% had chemotherapy. Clinical outcomes revealed FFLR 97.4%, FFRR 100%, FFDM 92.9%, CLBC 97.4%, DFS 90.3%, CSS 97.6%, and OS 79.0%, all 10-year actuarial. Late toxicities analyzed included skin pigmentation, edema, and pain (all grade 1/2) along with telangiectasias, induration (Table 1), fat necrosis, seroma and rib fracture. No grade 3 or 4 toxicities were noted except for 2% grade 3 telangiectasias and 2% grade 3 induration. Fat necrosis was seen in 14% and persistent seroma in 17%. Rib fracture was seen in 3 (7%) where 160% of the prescription dose was accepted during this treatment era. Cosmesis was good/excellent in 88% at 10 years. With median follow-up approaching 10 years, 2-day APBI demonstrates excellent clinical effectiveness, minimal late morbidity, and good/excellent cosmesis in the majority of patients. Dose constraints such as to ribs/chest wall have been refined from these results. Short-course APBI affords appropriately selected early-stage breast cancer patients irradiation in 2 days vs several weeks of whole breast external beam treatments. Further follow-up of 2-day APBI patients will be needed to substantiate these long-term findings.Abstract 1100; Table 1Chronic toxicities with 2-day APBI (n = 42)Toxicity GradeGrade 0Grade 1Grade 2Grade 3Hyperpigmentation24 (57%)17 (41%)1 (2%)Hypopigmentation37 (88%)5 (12%)Breast Pain26 (60%)14 (33%)2 (5%)Breast Edema28 (67%)12 (28%)2 (5%)Induration/Fibrosis7 (17%)14 (33%)20 (48%)1 (2%)Telangiectasia28 (67%)6 (14%)7 (17%)1 (2%) Open table in a new tab