[Intraoperative electron radiotherapy (IOERT) in the QUART sequence: a phase I study]

We evaluated the tolerance of a single dose of 800-1500 cGy, delivered with an electron beam from an IOERT-dedicated linear accelerator to the tumour bed in patients with breast cancer undergoing conservative treatment, instead of the traditional boost. We enrolled 27 patients (cT1-2, cN0). The first 6 received a dose of 800 cGy, 6 1000 cGy, 10 1200 cGy and 5 1500 cGy. External beam radiation therapy (EBRT) with a conventional schedule, 4000 cGy total dose, was performed after wound healing. The median gap between IOERT and EBRT was 8 weeks. Three patients with adverse prognostic factors undergoing chemotherapy, including doxorubicin or taxanes, received EBRT after completion of chemotherapy. One patient with a prosthesis implant had yielding of the surgical scar 8 months after IOERT (after 4 cycles of doxorubicin and 4 cycles of CMF complicated by frequent mastitis). Another patient with a large serum collection in the axilla manifested delayed scar formation. In the others no significant increase in healing time or surgery-related morbidity was observed. Another 4 patients developed mastitis. The cosmetic outcome was good in 26/27 patients. This treatment is well tolerated at all IOERT doses delivered. In the follow-up, to date, there have been no local relapses.