Breast boost using noninvasive image-guided breast brachytherapy vs. external beam: a 2:1 matched-pair analysis

Area of Science:

• Oncology
• Radiation Oncology
• Breast Cancer Treatment

Background:

• External beam (EB) boost and Norwood Interstitial Brachytherapy Boost (NIBB) boost are used in early-stage breast cancer treatment.
• Comparing clinical outcomes and toxicity between these boost techniques is crucial for treatment optimization.

Purpose of the Study:

• To compare clinical outcomes and toxicity in patients receiving NIBB boost versus EB boost for early-stage breast cancer.
• To evaluate the safety and efficacy of NIBB boost in comparison to conventional EB boost techniques.

Main Methods:

• A retrospective analysis compared 47 women treated with NIBB boost to 94 matched controls treated with EB boost (electron or 3-D conformal radiation).
• Patients were matched based on age, stage, chemotherapy use, and fractionation.
• Acute and late toxicity, as well as oncologic outcomes, were reviewed using the McNemar nonparametric test.

Main Results:

• Grade 2+ desquamation occurred in 39% of NIBB patients versus 52% of EB patients (P = .07).
• Predictors for acute desquamation included breast size, electron energy, and fractionation.
• Significantly less combined skin/subcutaneous toxicity (P = .046) was observed in the NIBB group, with only 2% developing Grade 2+ fibrosis compared to 9.5% in the EB group.

Conclusions:

• NIBB boost is associated with favorable short-term clinical outcomes compared to EB boost.
• NIBB boost demonstrates a potential for reduced late toxicity, specifically skin/subcutaneous fibrosis.