SABCS15: 'Weeding the garden' with radiation while continuing breast cancer therapy

"This study takes what has been a really successful approach to early stage breast cancer and moves it to the first presentation of metastatic disease," says Virginia Borges, MD, MMSc, director of the Breast Cancer Research Program and Young Women's Breast Cancer Translational Program at the University of Colorado Cancer Center.

The trial (NCT02364557), which is currently accruing patients, will eventually include 402 participants who have received up to six months of therapy for breast cancer and are recently diagnosed with less than three sites of metastasis. The trial will study progression free survival of women treated with standard systemic therapy compared with women whose sites of metastasis are resected using surgery and/or stereotactic body radiation while continuing systemic therapy. (Stereotactic body radiation focuses radiation on precisely targeted tumor sites, killing tumor tissue.)

"With this strategy, I've had young women with metastatic disease who are living without evidence of disease even 10 years out from diagnosis. Our early evidence shows the promise of individually resecting these sites of metastasis, but it's a question that cries out to be answered as definitively as possible," Borges says.

The trial also hopes to gather data that will let researchers define parameters or biomarkers that allow doctors to decide which patients are most likely to benefit from this "weeding the garden" approach or conversely, those who will do well without the added specific local treatments. .

"There's almost certainly a tipping point at which this doesn't make sense -- a number or degree or location of metastases at which individually resecting the metastases induces the potential for unnecessary side effects with unclear gain. Our hope is to discover this tipping point and discover who is most likely to benefit from this approach," Borges says.

The trial includes researchers representing three perspectives, those of clinical oncology, radiation oncology and surgery, each of which has traditionally brought a different viewpoint to the potential benefit of resecting individual sites of metastasis.

"The question needs to be answered," Borges says. "Right now we lack data that could help redefine the standard of care in these many situations of early metastatic disease."