Feasibility of intraoperative radiation therapy for early breast cancer in Japan: a single-center pilot study and literature review.

BACKGROUND

Intraoperative radiation therapy (IORT) is under evaluation in breast-conserving surgery because the feasibility of the IORT procedure including transportation of the patient under general anesthesia is not well established. Thus, this prospective single-center study aimed to test the feasibility of IORT at a single dose of 21 Gy in Japanese breast cancer patients.

METHODS

The primary endpoint was early toxicity; the secondary endpoint was late toxicity. Patients with histologically or cytologically proven primary early breast cancer were eligible. Inclusion criteria were as follows: (1) T < 2.5 cm; (2) desire for breast-conserving surgery; (3) age >50 years; (4) surgical margin >1 cm; (5) intraoperative pathologically free margins; and (6) sentinel node negative. Exclusion criteria were (1) contraindications to radiation therapy; (2) past radiation therapy for the same breast or chest; (3) extensive intraductal component; and (4) a tumor located in the axillary tail of the breast. All patients gave written informed consent. Partial resection was performed with at least a margin of 1 cm around the tumor. The patient was transported from the surgical suite to the radiation room. Radiation (Clinac(®) 21EX, Varian Medical Systems, Inc.) at 21 Gy was delivered directly to the mammary gland. Toxicity was evaluated with the Common Terminology Criteria for Adverse Events V4.0.

RESULTS

Five patients were enrolled in this pilot study and received 21 Gy. Follow-up ranged from 7.8 to 11.0 months (median 10.2). Intraoperative transportation to the radiation room during the surgical procedure under general anesthesia was performed safely in all patients. Treatment-related toxicities within 3 months were deep connective tissue fibrosis (grade 1, n = 3) and pain (grade 1, n = 3). There was no case of wound infection, wound dehiscence, or soft tissue necrosis. Overall, there was no severe adverse event.

CONCLUSIONS

The procedure was tolerated very well in this first group of Japanese female patients treated with IORT, as was the case with European women. A longer follow-up is needed for the evaluation of any potential late side effects or recurrences. A phase II study is now being conducted for the next group of patients (UMIN000003578).