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Ten-year outcomes of accelerated partial breast irradiation compared with whole breast irradiation: A matched-pair analysis.
General Session IV: Poster Discussion A
J Clin Oncol 31, 2013 (suppl 26; abstr 55)
Abstracts that were granted an exception in accordance with ASCO's Conflict of Interest Policy are designated with a caret symbol (^).
Background: Breast conserving therapy (BCT) represents a standard of care in the management of early stage breast cancer; while adjuvant radiation therapy was traditionally delivered using whole breast irradiation (WBI), accelerated partial breast irradiation (APBI) offers an alternative to WBI that shortens the duration of treatment and may improve toxicity profiles and quality of life. The purpose of this analysis is to compare clinical outcomes of patients treated with WBI versus APBI. Methods: A total of 3,009 patients were treated with BCT at single institution between 1980 and 2012 with 2,528 patients receiving WBI and 481 patients receiving APBI (interstitial or balloon-based). A matched-pair analysis was performed with patients matched according to age (+/- 3 years), T stage (Tis vs T1 vs T2), and estrogen receptor (ER) status (+/-). All patients had a minimum of 12 months of follow up. A total of 247 matches were made with clinical outcomes compared using the Kaplan-Meier method. Results: Mean follow-up was 8.1 years for WBI vs. 7.8 years for APBI (p<0.001), a difference of less than 4 months. There were no differences with respect to age (p=0.88), tumor stage (p=1.0), or ER status (p=1.0). Long-term cosmesis was good to excellent in 94% vs. 95% of patients (p=0.78). WBI patients demonstrated a trend for slightly larger tumors (13.0 vs. 11.4 mm, p=0.06). At 10 years, no difference in ipsilateral breast tumor recurrence (4% vs. 4%, p=0.11), regional recurrence (1% vs. 1%, p=0.20), distant metastases (3% vs. 6%, p=0.47), disease free survival (93% vs. 91%, p=0.10), or contralateral breast failure (9% v. 3%, p=0.06) was noted when comparing WBI and APBI. In addition, 10 year cause-specific survival (94% v. 93%, p=0.72) and overall survival (83% vs. 75%, p=0.34) were similar. Conclusions: At 10 years, no differences in locoregional recurrence, distant metastasis or survival were found between patients undergoing whole breast irradiation or accelerated partial breast irradiation using interstitial catheter or balloon-based brachytherapy. These data represent one of the only APBI series with prolonged follow-up and show similar outcomes in a matched group of patients undergoing WBI or APBI.
Abstracts by Jessica Wobb:
Propensity-score matched pair comparison of brachytherapy-based accelerated partial breast irradiation versus whole breast Canadian hypofractionation.
Impact of the number of cautionary/unsuitable risk factors on outcomes following accelerated partial breast irradiation.