Researchers at The University of Kansas Cancer Center have launched a clinical trial that eliminates radiation from the treatment protocol for an invasive type of breast cancer that accounts for one-fifth of all breast cancer patients.

These are the patients who have breast tumors that contain high levels of a protein known as HER2 (human epidermal growth factor receptor 2), which speeds up the growth of cancer cells.

Treatment for HER2-positive cancer typically begins with chemotherapy to shrink the tumors, followed by surgery to remove it. Patients then undergo radiation therapy to knock out any lingering malignant cells.

Fifteen years ago, omitting radiation therapy would have been unthinkable. The risk of recurrence was just too high. But that was then. In the last decade, breakthrough drugs such as trastuzumab and pertuzumab, which shut down the HER2 protein, have transformed treatment for this kind of breast cancer. The addition of these new targeted drugs to the chemotherapy regimen has slashed the risk of recurrence by more than half.

In 2012, Melissa Mitchell, M.D., assistant professor of radiation oncology at the KU School of Medicine and a researcher affiliated with the KU Cancer Center, was a new faculty member at a tumor conference listening to other oncologists report how rare it is to see a recurrence of breast cancer in many early-stage HER2-positive patients.

They were talking specifically about patients for whom chemotherapy, combined with these targeted drugs, destroyed all cancer. When the surgeon went in to remove the tumor after the chemo, the cancer was already dead, which meant it contained zero live cancer cells.

How the trial works

She and Mitchell follow researchers are in the process of recruiting post-menopausal women at least 50 years of age who are in the early stages of HER2-positive invasive ductal carcinoma (a type of breast cancer that originates in the milk ducts), and who have clear lymph nodes. Patients in the trial will choose whether they prefer to be in the intervention or control groups.

"There is some fear about radiation. Other investigators are studying the potential to eliminate surgery in this same population, but surveyed patients have said they would rather skip radiation than surgery. Patients feel more comfortable having cancer cut out," said Mitchell.

Patients in the study who opt to omit radiation as part of their treatment after lumpectomy will have follow-up examinations every three months for five years.

The tests will include imaging (mammograms or MRIs), and patients will be asked to fill out surveys on quality of life and the cosmetic aspects of their treatment. Their results will be compared with those of the controls: patients who opted to have the standard radiation.

"We hope to find that without radiation, patients do fantastic, that they do not have a recurrence and all while having less risk of side effects, including heart and lung damage," said Mitchell.