IOERT successful as boost during breast conservation surgery

Dec 13, 2010

Breast cancer patients undergoing breast conservation surgery who have an intraoperative electron radiation therapy (IOERT) boost followed by whole-breast irradiation have a much lower rate of cancer recurrence 10 years after treatment, according to a study presented at the San Antonio Breast Cancer Symposium.

Radiation oncologists from the Paracelsus Medizinische Privatuniversität in Salzburg, Austria, presented findings of a nonrandomized study comparing ipsilateral breast cancer recurrence in patients treated for invasive breast cancer. The lead author of the study was Roland Reitsamer, MD.

The researchers evaluated the outcomes of 378 patients: Of this group, 188 received conventional radiation therapy with a boost at the end of treatment, and 190 received an IOERT boost during the breast conservation surgery before undergoing conventional radiation therapy.

All patients received 51-56 Gy of radiation delivered with conventional electron-beam radiation therapy. The women who had a single fraction of IOERT received an intraoperative electron boost of 9 Gy, whereas the other group received a 12-Gy boost upon completing the course of treatment.

Patients in the two groups were comparable with respect to age, menopausal status, tumor size, histological type, grading, and axillary lymph node status, Reitsamer said. All patients had clear margins greater than 3 mm. Patients diagnosed with ductal carcinoma in situ were excluded, as well as those with multicentric disease.

A comparison of 10-year actuarial rates of ipsilateral breast cancer recurrence showed that excellent local control was achieved for the group that received a boost at the time of treatment.

10-year recurrent rates: conventional versus IOERT boost

	Conventional boost	IOERT boost
Ipsilateral breast tumor recurrence	7.1%	2.7%
True local recurrence	4.8%	0.7%
Distant recurrence	14.2%	13.6%
Disease-free survival	82.4%	84.0%