Oakland University William Beaumont School of Medicine, Beaumont Cancer Institute, Royal Oak, MI
Peter Y. Chen , John Ben Wilkinson , Chirag Shah , Jessica Wobb , Michelle Wallace , Hong Ye , Ovidiu Marina , Pamela Benitez , Nayana Dekhne , Donald S. Brabbins , Frank Vicini
Background: Given the initial report of the RAPID trial with greater morbidity for 3-D conformal external beam APBI [3D-APBI] vs. Canadian Hypofractionation [CHfx], a propensity-score matched-pair analysis of brachytherapy-based APBI [B-APBI] vs. CHfx was performed to assess efficacy, toxicities, and cosmesis. Methods: Early-stage breast cancer patients treated with B-APBI or CHfx were reviewed. With ≥ 1y follow-up [FU], B-APBI (n=108) pts were matched 1:1 to CHfx (n=108) by age, T-stage, nodal/ER status, endocrine or chemotherapy and laterality. Ipsilateral breast tumor recurrence (IBTR), regional recurrence (RR), distant metastasis (DM), contralateral breast cancer (CLBC), cause-specific survival (CSS), overall survival (OS) and disease-free survival (DFS) were compared by Kaplan-Meier (log-rank test). Toxicities were graded per CTCAE v3 and comesis per Harvard criteria. Results: Median FU was 5.7 y (1.0-17.8) for B-APBI and 2.1 y (1.0-5.7) for CHfx [p < 0.001]. Patients did not differ by match criteria. In comparing B-APBI to CHfx, median age was 69.0 vs. 70.0 [p = 0.72]; for laterality, T-stage, nodal/ER status, endocrine or chemotherapy, no significance [NS] was noted between the 2 groups [p = 0.79, 1.0, 0.60, 0.09, 0.15, and 0.16 respectively]. Comparing B-APBI to CHfx, NS was seen in 5-y actuarial rates of IBTR [1% vs. 0% p = 0.35], RR [0% both], DM [3.4% vs. 0% p = 0.25], CLBC [2.3% vs. 2% p = 0.63], CSS [94.3% vs. 100% p = 0.47], OS [87.7% vs. 88.3% p = 0.71] & DFS [97.5% vs. 100% p = 0.52]. The majority of maximal late toxicities were Gr 1-2. Of toxicities analyzed, including pigmentary changes, edema, pain, induration, volume reduction, telangiectasia, fat necrosis and seroma, only Gr 2-3 hyperpigmentation was significantly higher in the CHfx [8% B-APBI vs. 22% CHfx p = 0.017]. Good/excellent cosmesis was seen in > 93% in both groups. Conclusions: With FU of >5 yrs, B-APBI has similar efficacy and cosmesis but less morbidity vs. CHfx; the lesser toxicity of B-APBI vs. CHfx is in contradistinction to the RAPID results comparing 3D-APBI vs. CHfx. Further FU and more patients are needed to substantiate these findings.
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