Evidence continues to emerge suggesting that certain patients with breast cancer with oligometastatic disease may benefit from local ablation of their metastases. However, much of that evidence comes from single-center or single-arm trials, according to Steven Chmura, MD, PhD, Associate Professor of Radiation and Cellular Oncology at the University of Chicago.

“Many of these reports have shown the same thing,” Dr. Chmura said. “In a select group of patients who seem to have limited disease, these patients do better with ablation than you would expect of the general population.”

In more recent years, some phase 2 trials have compared palliative standard of care treatments with or without ablation and shown benefit, but these were across several tumor types. Breast cancer-specific data are lacking, Dr. Chmura said.

Dr. Chmura will moderate the SABCS 2021 Clinical Science Forum: The Promise and Reality of Oligometastatic Ablation for Breast Cancer on Thursday, December 9, at 2:00 pm CT. The session will include two state-of-the-art presentations covering what is currently known about ablation of oligometastatic disease in breast cancer.

Yolande Lievens, MD, PhD, Associate Professor and Chair of Radiation Oncology at Ghent University Hospital in Belgium, will discuss how to define oligometastatic disease, the current consensus on some of the terminology, and current practice patterns in breast cancer.

“There currently seem to be two broad categories for defining oligometastatic disease,” Dr. Chmura said. “The first involves looking at the number of visible metastases and the second is related to response to initial systemic therapy.”

In response to the rapidly increasing interest and growing evidence in the use of metastasis-directed radiotherapy for oligometastatic disease, Dr. Chmura noted that ASTRO and ESTRO published a consensus document in 2020 in an attempt to better define oligometastatic disease.

Also during this SABCS forum, David Palma, MD, PhD, a radiation oncologist at the London Health Sciences Centre and a clinician-scientist with the Ontario Institute for Cancer Research in Canada, will discuss the current literature and where there are still gaps in knowledge when it comes to oligometastatic disease specific to breast cancer.

One of the ongoing challenges in breast cancer research, Dr. Chmura said, is that standard of care systemic therapies—such as HER2-directed agents and CDK 4/6 inhibitors—keep improving outcomes.

“Trials are not trying to replace those therapies but are adding ablation on top of those,” he said. “What we have to find out is if that really improves survival or just adds toxicity.”

Dr. Chmura is principal investigator of the NRG BR002 trial, which he hopes will provide some answers. NRG BR002 is a phase 2R/3 trial of standard of care therapy with or without stereotactic radiotherapy and/or surgical ablation for newly oligometastatic breast cancer.

“These results are being analyzed and, in the next few months, we hope to have more definitive evidence as to whether or not early intervention can improve progression-free survival,” Dr. Chmura said.

Following Dr. Lievens’ and Dr. Palma’s presentations, Dr. Chmura hopes to devote a significant amount of time to audience questions and further discussion.

“I hope that session participants will learn more about current accepted definitions and some of the ongoing trials specific to breast cancer,” Dr. Chmura said. “I hope they take away some hope that there may be improved therapeutic options for this select group of patients but, importantly, also caution or skepticism to not just apply results from other disease types to breast cancer.”