Phase II Trial of Five-Fraction Accelerated Partial Breast Irradiation (APBI) Using Noninvasive Image-Guided Breast Brachytherapy (NIBB)

Jaroslaw T Hepel; Kara L Leonard; Catheryn M Yashar; John P Einck; Sandra J Sha; Thomas A DiPetrillo; Doreen L Wiggins; Theresa A Graves; David A Edmonson; Jennifer S Gass; Mark J Rivard; Brown University Oncology Research Group; David E Wazer

doi:10.1016/j.ijrobp.2023.12.026

Phase II Trial of Five-Fraction Accelerated Partial Breast Irradiation (APBI) Using Noninvasive Image-Guided Breast Brachytherapy (NIBB)

Int J Radiat Oncol Biol Phys. 2023 Dec 25:S0360-3016(23)08260-3. doi: 10.1016/j.ijrobp.2023.12.026. Online ahead of print.

Affiliations

¹ Department of Radiation Oncology, Rhode Island Hospital, Providence, Rhode Island; Department of Radiation Oncology, Tufts Medical Center, Tufts University, Boston, Massachusetts; Brown University, Providence, Rhode Island. Electronic address: jhepel@lifespan.org.
² Department of Radiation Oncology, Rhode Island Hospital, Providence, Rhode Island; Department of Radiation Oncology, Tufts Medical Center, Tufts University, Boston, Massachusetts; Brown University, Providence, Rhode Island.
³ Department of Radiation Oncology, University of California, San Diego, La Jolla, California.
⁴ Department of Radiation Oncology, University of Kansas Medical Center, Kansas City, Kansas.
⁵ Department of Radiation Oncology, Watson Clinic, Lakeland, Florida.
⁶ Brown University, Providence, Rhode Island; Department of Surgery, Rhode Island Hospital, Providence, Rhode Island.
⁷ Brown University, Providence, Rhode Island; Department of Surgery, Women and Infants Hospital, Providence, Rhode Island.
⁸ Brown University, Providence, Rhode Island.

PMID: 38151190
DOI: 10.1016/j.ijrobp.2023.12.026

Abstract

Purpose/objective(s): NIBB has potential advantages over other APBI techniques by delivering highly conformal radiation with minimal collateral dose to the heart and lung compared with external beam techniques, but unlike other brachytherapy techniques NIBB is non-invasive. Previous data has shown encouraging outcomes using a 10-fraction regimen. To improve efficiency, convenience, and cost, reduction in the fraction number is desirable. Final results of a prospective phase II trial are reported.

Materials/methods: NIBB APBI was delivered using 28.5Gy in 5 fractions daily over 1 week. Patient eligibility criteria required: invasive carcinoma ≤2.0 cm or DCIS ≤3.0 cm, ER positive (if invasive), lymph node negative, LVI absent, and lumpectomy with margins negative by 2mm. The primary endpoint was grade ≥ 2 subcutaneous fibrosis/induration <30%. Secondary endpoints included any late toxicity, cosmetic outcome, and local control.

Results: 40 patients were treated with a median follow-up of 59.7 months. The mean age was 67 years (50-89 years) and tumor size was 1.0cm (0.3-2.0cm). 80% had invasive carcinoma. The mean breast separation with compression was 6.7cm (3.5-8.9cm). The 5-year actuarial local control was 96.6% and overall survival was 96.9%. Grade 2 and 3 late toxicities were 15% and 0%, respectively. The rate of grade 2 subcutaneous fibrosis/induration was 2.5% (+/-2.5%) meeting the study's primary endpoint. The most common late toxicity of any grade was skin telangiectasia; 22.5% grade 1 and 15% grade 2. Only breast separation was associated with telangiectasia risk, p=0.002. Overall cosmetic outcome was excellent, good, and fair/poor in 75%, 25%, and 0%, respectively.

Conclusions: NIBB APBI delivered in 5 fractions results in a low rate of late toxicity and a high rate of good/excellent cosmetic outcomes. Telangiectasia risk can be minimized by keeping breast separation ≤7.0cm. The local failure rate was appropriately low. Further investigation of this technique is warranted.