Researchers at The University of Kansas Cancer Center have launched a clinical trial evaluating the need for radiation therapy after surgical removal of an aggressive type of breast cancer that has not spread to lymph nodes.
Approximately 1 in 5 patients with breast cancer are positive for human epidermal growth factor receptor 2 (HER2). HER2-positive is a term used to describe an aggressive type of breast cancer that expresses high levels of this cell-surface protein, leading to increased tumor growth and potential to spread.
Standard treatment for HER2-positive breast cancer usually involves sequential chemotherapy to shrink the tumor, surgery to remove it, and radiation therapy to eliminate any potentially remaining cancer cells and prevent relapse.
However, the recent addition of revolutionary medicines that target the HER2 protein — such as Herceptin (trastuzumab) — into the chemotherapy plan has reduced the risk of relapse by more than half.
These targeted therapies have been found to completely eliminate the tumor in many patients, and according to Melissa Mitchell, MD, PhD, the researcher leading the clinical trial, patients with that kind of strong response to chemotherapy frequently ask why they have to undergo radiotherapy.
“The treatment drugs have just become so effective that it made us think that maybe we could scale back and spare patients the side effects of radiation,” Mitchell said in a press release.
The potential side effects of radiotherapy include skin reactions; fatigue; swelling of the arm, hand, or breast area; change in breast shape, size, or color; and long-term heart and lung damage. Rare cases of secondary cancer due to radiation have also been reported.
Radiation therapy also requires frequent visits, time away from work, and potentially long travel distances to a radiation treatment facility.
Mitchell, who is an assistant professor of radiation oncology at the KU School of Medicine, and colleagues at The University of Kansas Cancer Center have now launched the first clinical trial (NCT03460067) evaluating whether early-stage HER2-positive breast cancer patients need radiotherapy to be cancer-free. The trial is currently enrolling.
The researchers aim to recruit 78 post-menopausal women at least 50 years of age with early-stage HER2-positive ductal carcinoma — a type of breast cancer that originates in the milk ducts — that has not spread to the lymph nodes.
Eligible patients must have had a complete response to Herceptin-based chemotherapy prior to breast-conserving surgery — when only the tumor and some surrounding tissue is removed — and plan for completion of one year of Herceptin.
After breast-conserving surgery, participants will have the option to undergo standard radiotherapy (control group) or skip it (intervention group).
Those who choose to skip radiotherapy will have follow-up examinations at one month after surgery, and every three months for five years, to look for any cancer relapse. Exams will include mammograms or magnetic resonance imaging (MRI).
Overall survival, quality of life — assessed through the self-administered FACT-B+4 questionnaire — and cosmetic aspects of the breast — measured by Breast-Q — will be assessed at the beginning of the study, at the first post-operative visit, and at the one-year post-operative visit.
“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,” Mitchell said.
Mitchell is also involved in another study investigating whether shorter period of radiotherapy — three to four weeks instead of the standard six to seven weeks — is equally effective in patients with breast cancer that has spread to the lymph nodes.