A single dose of targeted radiation during surgical treatment for early breast cancer could be an alternative to a standard multiweek course of radiotherapy, according to a pair of studies published in The Lancet and The Lancet Oncology.

Most women who undergo lumpectomy to treat breast cancer also receive a course of external beam radiotherapy (EBRT) following the surgery. While EBRT reduces risk of recurrence, it requires 20-30 daily sessions and can result in adverse side-effects. This forces some women to forego lumpectomy and instead receive a full mastectomy.

The Lancet study, conducted by Michael Baum, MD, of University College London, and colleagues examined whether the TARGIT method of intraoperative radiotherapy delivered by a miniature x-ray could match up with a standard course of EBRT. Between March 24, 2000, and June 25, 2012, a total of 3,451 patients were enrolled in the study, with roughly half receiving a one-time TARGIT treatment and the other half receiving standard EBRT.

The study included two strata, the first involving 1,140 women who received TARGIT at the same time as initial surgery compared with 1,158 women receiving EBRT. The second strata compared 581 women who receive TARGIT as a second procedure within an average of 37 days following surgery and 562 women who received EBRT.

About 80 percent of patients treated with TARGIT completed their surgery and radiotherapy under a single anesthetic without any supplemental EBRT, reported Baum and colleagues. Overall mortality was 3.9 percent with TARGIT and 5.3 percent with EBRT. For all participants, the difference in five-year risk for local recurrence between treatments was within 2.5 percent, which meant TARGIT should be considered “non-inferior” to EBRT, according to the authors.

The second study, appearing in The Lancet Oncology, involved a similar targeted radiation treatment called ELIOT, which is an intraoperative electron beam radiotherapy technique. Umberto Veronesi, MD, of the European Institute of Oncology in Milan, and colleagues treated 651 women with ELIOT during lumpectomy surgery and compared results to a control group of 654 women receiving EBRT after surgery.

ELIOT did not fare as well as TARGIT for recurrence rate. After five years, recurrence rates were 2.5 percent or 4.4 percent in the ELIOT group, depending on whether only true local recurrence or any ipsilateral recurrence was included. Only 0.4 percent of women in the EBRT control group experienced any recurrence.

While ELIOT did not benefit recurrence rates, the authors noted that overall survival did not significantly differ between ELIOT patients and the control group, and that some women may feel it is worth the greater risk of recurrence to avoid a lengthy course of EBRT.

A linked commentary from David Azria, MD, PhD, and Claire Lemanski, MD, of the Montpellier Cancer Research Institute, France, stated that more research is needed, but that the results of the studies show promise. “The new data from TARGIT-A and ELIOT reinforce our conviction that intraoperative radiotherapy during breast-conserving surgery is a reliable alternative to conventional postoperative fractionated irradiation, but only in a carefully selected population at very low risk of local recurrence.”