Women with HER2-positive breast cancer that has spread to distant organs live longer if they have surgery to remove their primary tumor, according to research presented at the recent American Association for Cancer Research (AACR) Annual Meeting 2019 in Atlanta, Georgia.
The findings were featured on the poster, “The impact of primary tumor surgery on survival in HER2 positive stage IV breast cancer patients in the current era of targeted therapy,” and presented by Ross Mudgway, a medical student at the University of California, Riverside School of Medicine.
Between 20-30% of patients with stage 4 breast cancer (a stage in which cancer has already spread to other organs) are HER2-positive. HER2, or human epidermal growth factor receptor 2, is a protein that sends signals to stimulate cell growth and is normally associated with aggressive forms of breast cancer.
According to Mudgway, the study’s lead author, HER2-positive breast cancer was normally associated with poor clinical outcomes for patients. However, with the development of HER2-targeting therapies, such as Herceptin (trastuzumab) or Kadcycla (ado-trastuzumab emtansine), patients have seen their survival outcomes improve significantly.
The recommended course of treatment for most patients with HER2-positive breast cancer is a form of systemic therapy, such as chemotherapy, targeted therapy, or hormonal therapy. According to Mudgway, surgery may also be offered as a form of treatment, but so far its impact on patients’ survival has been controversial.
To determine the impact of primary tumor resection surgery (a surgical procedure to remove the primary tumor) on the survival of patients diagnosed with advanced metastatic HER2-positive breast cancer, Mudgway and his team carried out a retrospective cohort study involving 3,231 women whose records had been stored at the National Cancer Database from 2010 to 2012.
According to medical records, 89.4% of the women had been treated with chemotherapy or targeted therapy, 37.7% with hormone therapy, and 31.8% with radiation therapy.
Only 35% had undergone primary tumor resection surgery, and these women tended to be younger than those who did not (mean age of 56 versus 59), and were followed for a median period of 21 months.
Results showed that breast cancer surgery was linked to a 44% lower risk of death, assuming most patients had already been treated with a form of systemic therapy.
“This suggests that, in addition to standard HER2-targeted medications and other adjuvant therapy, if a woman has stage 4 HER2-positive breast cancer, surgery to remove the primary breast tumor should be considered,” Sharon Lum, MD, professor in the department of surgery-division of surgical oncology and medical director of the Breast Health Center, Loma Linda University Health, said in a press release.
Researchers also found that other factors, including type of insurance coverage and ethnicity, also played an important role in patients’ overall survival.
According to their findings, women who had Medicare or private insurance had higher chances of undergoing surgery, and were therefore more likely to live longer than those who had Medicaid or did not have insurance. They also found that white women were more likely to undergo surgery compared to non-Hispanic black women
“These results suggest disparities in health care due to race and socioeconomic factors, and these must be addressed,” Mudgway said.
According to the study’s investigators, there are multiple factors that may affect a clinician’s decision on whether to recommend primary tumor resection surgery to patients with advanced breast cancer. These may include the presence of additional comorbidities, overall life expectancy, and response to other forms of therapy.
“Doctors may be most willing to operate on women who are healthier overall and are, therefore, more likely to experience a positive outcome. Further research would be needed to confirm the survival benefit suggested by this study,” Lum said.