Long-term outcomes now being reported confirm earlier reports from the same trial showing efficacy for the use of targeted intraoperative radiotherapy (TARGIT) in patients with early.
This novel approach, which delivers a one-off blast of radiation directed at the tumor bed and is given during, has similar efficacy and lowers non–breast cancer mortality when compared with whole-breast external beam radiotherapy (EBRT), which is delivered in fractions over 3-6 weeks after surgery.
Giving the boost of radiation during surgery has numerous benefits, say the authors: it is more convenient for patients and saves on healthcare costs.
However, the controversy over local recurrence rates, sparked by the earlier results, still remains. The difference in the 5-year local recurrence rate between TARGIT and EBRT was within the 2.5% margin for non-inferiority: the rate was 2.11% in 1140 TARGIT recipients, compared with 0.95% in 1158 EBRT recipients, for a difference of 1.16% (13 recurrences).
The new longer-term results from theAugust 20 in the BMJ, and confirm earlier results from this trial . Meanwhile, other approaches to intraoperative radiotherapy (IORT) have also been reported.
Nevertheless, whole-breast radiotherapy remains the standard of care today, note the authors.
“The biggest battle the TARGIT investigator family has faced is our challenge to the conventional dogma that radiotherapy has to be given in multiple daily doses, and moreover that whole-breast radiotherapy is always essential,” said lead author Jayant Vaidya, MD, professor of surgery and oncology at University College London, UK. He was one of the team of investigators that together developed the TARGIT approach in the 1990s, as he recalls in a.
It is unclear whether the TARGIT-A long-term outcomes will change practice,, associate program director of the Harvard Radiation Oncology Residency Program and assistant professor of radiation oncology at Massachusetts General Hospital, Boston, told Medscape Medical News.
She noted there wasover the earlier reports from TARGIT-A, and those findings “did little to change practice patterns over the past 6 years,” she said.
“With the publication of longer-term follow-up, my expectation would be that perceptions of IORT will remain unchanged in the radiation oncology community, and that those previously supportive of the TARGIT-A approach will continue to embrace it while those initially skeptical will be unlikely to change practice despite the longer-term results,” she said.
“However, despite the controversy surrounding TARGIT-A, it is heartening as a clinician who cares for breast cancer patients to see a trend within the early breast cancer clinical trials space toward the evaluation of increasingly targeted and abbreviated courses of radiation,” Jimenez commented.
Details of new long-term results
TARGIT-A is an open-label, 32-center multinational study conducted in 2298 women aged 45 years or older with early-stage invasive ductal carcinoma who were eligible for breast-conserving surgery. Between March 24, 2000, and June 25, 2012, participants were randomized 1:1 to risk-adapted TARGIT immediately after lumpectomy or to whole-breast EBRT delivered for the standard 3-6 week daily fractionated course.
At a median follow-up of 8.6 years — with some patients followed for nearly 19 years — no significant difference was seen between the treatment groups in local recurrence-free survival (167 vs 147 events; hazard ratio, 1.13); invasive local recurrence-free survival (154 vs 146 events; HR, 1.04); mastectomy-free survival (170 vs 175 events; HR, 0.96); distant disease-free survival (133 vs 148 events; HR, 0.88); overall survival (110 vs 131 events; HR, 0.82); or breast cancer mortality (6 vs 57 events; HR, 1.12).
“Mortality from other causes was significantly lower (45 vs 74 events; HR, 0.59),” the authors note.