Clinical and Translational Radiation Oncology (Jul 2023)

Long-term outcomes of intraoperatively-placed applicator brachytherapy for rapid completion of breast conserving treatment: An analysis of a prospective registry data

  • Haeyoung Kim,
  • Tina J. Hieken,
  • Feven Abraha,
  • James W. Jakub,
  • Kimberly S. Corbin,
  • Keith M. Furutani,
  • Judy C. Boughey,
  • Bradley J. Stish,
  • Christopher L. Deufel,
  • Amy C. Degnim,
  • Dean A. Shumway,
  • Safia K. Ahmed,
  • Mara A. Piltin,
  • Nicole P. Sandhu,
  • Amy L. Conners,
  • Kathryn J. Ruddy,
  • Robert W. Mutter,
  • Sean S. Park

Journal volume & issue
Vol. 41
p. 100639

Abstract

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Background and purpose: To evaluate the long-term outcome of accelerated partial breast irradiation utilizing intraoperatively placed applicator-based brachytherapy (ABB) in early-stage breast cancer. Materials and methods: From our prospective registry, 223 patients with pTis-T2, pN0/pN1mic breast cancer were treated with ABB. The median treatment duration including surgery and ABB was 7 days. The prescribed doses were 32 Gy/8 fx BID (n = 25), 34 Gy/10 fx BID (n = 99), and 21 Gy/3 fx QD (n = 99). Endocrine therapy (ET) adherence was defined as completion of planned ET or ≥ 80% of the follow-up (FU) period. Cumulative incidence of ipsilateral breast tumor recurrence (IBTR) was estimated and influencing factors for IBTR-free survival rate (IBTRFS) were analyzed. Results: 218/223 patients had hormone receptor-positive tumors, including 38 (17.0%) with Tis and 185 (83.0%) with invasive cancer. After a median FU of 63 months, 19 (8.5%) patients had recurrence [17 (7.6%) with an IBTR]. Rates of 5-year IBTRFS and DFS were 92.2% and 91.1%, respectively. The 5-year IBTRFS rates were significantly higher for post-menopausal women (93.6% vs. 66.4%, p = 0.04), BMI < 30 kg/m2 (97.4% vs. 88.1%, p = 0.02), and ET-adherence (97.5% vs. 88.6%, p = 0.02). IBTRFS did not differ with dose regimens. Conclusions: Postmenopausal status, BMI < 30 kg/m2, and ET- adherence predicted favorable IBTRFS. Our results highlight the importance of careful patient selection for ABB and encouragement of ET compliance.

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