Intraoperative radiotherapy in women with early breast cancer treated by breast-conserving therapy

Abstract

Background: Previous studies demonstrated the feasibility of intraoperative radiotherapy (IORT) to the primary tumour bed using a miniature electron beam driven X-ray source for early breast cancer. This study aimed to evaluate the feasibility of IORT as a tumour bed boost after whole breast irradiation (WBI) in breast conserving therapy.

Methods: This was a single-arm prospective trial for women with breast cancer measuring <3 cm. After breast-conserving surgery, a single IORT dose of 5 Gray (Gy) prescribed to 10 mm from the applicator surface was delivered to the breast tissues using 50 kV X-ray followed by standard WBI. The feasibility rate of protocol therapy was defined as the percentage of all women who completed both IORT and WBI. A desirable completion rate was >90%. The protocol therapy would be considered unsuitable for further development if the completion rate was <75% or severe acute toxicity occurred in >15% of women who received IORT.

Results: Sixty patients were recruited for the study. IORT and WBI were delivered in 58 and 55 patients, respectively. Thus, the feasibility rates of IORT alone and both IORT and WBI were 97% (95% confidence interval (CI), 89-99%) and 92% (95% CI, 83-97%), respectively. A severe surgical complication or grade 3 or 4 acute radiation toxicity were identified in 10% (6/58) of women who had IORT.

Conclusion: Tumour bed boost using IORT in women with early breast cancer treated with conservative surgery and WBI was shown to be feasibly consistent with previous studies.