Surgery, in addition to treatments like chemotherapy and radiation therapy, may improve survival for certain patients with metastatic breast cancer. A research team studied nearly 13,000 patients with stage IV disease and found that those who had surgery in addition to other treatments had a survival advantage over those who had other treatments alone. These findings were published by Stahl et al in Annals of Surgical Oncology.

Stage IV breast cancer accounts for 6% of newly diagnosed breast cancer cases. Systemic therapy, which may include treatments like chemotherapy, hormone therapies, and immunotherapies, is routinely part of treatment plans for those patients. The benefits of surgery to remove the primary breast cancer are currently only recommended for relieving symptoms of advanced breast cancer such as pain and bleeding.

Surgery is the standard of care for some other types of metastatic cancers. Lead study author Kelly Stahl, MD, a surgical resident at Penn State Milton S. Hershey Medical Center, said that previous studies evaluating surgical interventions for metastatic breast cancer produced conflicting results, which has led to a lack of consensus among clinicians and researchers.

“Results from previous trials evaluating surgical benefit in [patients with] metastatic breast cancer have been questioned because of the small number of participants or the fact that patients weren't also receiving chemotherapy or other systemic therapies,” said Dr. Stahl in a press release. “We felt another key factor missing from those studies was whether the biologic subtype of breast cancer affected the survival rates in relation to surgical intervention.”

Study Methods

Researchers worked to identify 12,838 patients with stage IV breast cancer added to the National Cancer Database from 2010 to 2015 and whether these patients’ cancer cells had the growth-promoting protein HER2 and hormone receptors for estrogen and progesterone, which can fuel cancer growth. The researchers said knowing these characteristics of a cancer's biologic subtype can help determine which treatment plans may be effective.

Dr. Stahl studied patients who either had systemic therapy alone; had systemic therapy and surgery; or had systemic therapy, surgery, and radiation. She and her coauthors then evaluated whether certain biologic subtypes of breast cancer and timing of chemotherapy were associated with survival advantages.

“We evaluated whether the hormone status had an influence on surgical benefit in these treatment-responsive [patients with] breast cancer,” said study coauthor Daleela Dodge, MD, Associate Professor of Surgery and Humanities at Penn State Cancer Institute. “Some types of breast cancer, especially like triple-negative, where the cancer is hormone receptor– and HER2-negative, are not very responsive to treatment…. [O]ur goal was to see if surgery made a difference in metastatic breast cancers that were responsive to treatment.”

The researchers excluded patients who died within 6 months of their diagnoses in order to ensure that treatment-responsive cancers were being studied.

Effect of a Surgical Intervention

The research team found that patients with a surgical intervention tended to have a longer length of survival compared to patients with other treatment plans. Patients whose cancers were HER2-positive especially saw prolonged survival when their treatment plan included surgery.

Dr. Stahl and her coauthors further analyzed the patients who had undergone surgery to see whether receiving chemotherapy before or after surgery had an impact on survival. They found that regardless of hormone receptor or HER2 status, patients who received systemic therapy—including chemotherapy and targeted treatments—before surgery tended to live longer than those who had surgery before systemic treatment.

“Not only did we find that surgery may be beneficial for [patients with] treatment-responsive metastatic breast cancer, we also uncovered that getting chemotherapy before that surgery had the greatest survival advantage in patients with positive HER2 and estrogen and progesterone receptor status,” said study coauthor Chan Shen, PhD, Associate Professor of Surgery at Penn State Cancer Institute.

The researchers said that randomized, controlled trials evaluating the role of surgery after systemic therapy in a younger demographic with minimally metastatic cancers could be used to confirm their results, but added that patient resistance to random assignment in trials like this have resulted in poor study recruitment. Therefore, they encourage clinicians to evaluate real-world evidence, including their study, to choose the optimal treatment for their patients with metastatic breast cancer.

“[Patients with stage IV breast cancer] who are responsive to systemic therapy may be able to benefit from the addition of surgery regardless of their biologic subtype,” concluded Dr. Stahl.

Disclosure: For full disclosures of the study authors, visit link.springer.com.