When a patient first presents to a doctor with signs and symptoms of having breast cancer that has metastasized to other parts of the body, the prospects of long-term survival are dim. But now, a new study presented at the annual meeting of the American Society of Clinical Oncology suggests that women with metastatic HER2+ breast cancer are generally living longer, compared with women treated in previous years.
Between 2010 and 2018, the overall survival for 5,576 women (99% women) with HER2+ metastatic breast cancer enrolled in this study improved 5.6% each year of the study. The study also showed a 6.4% improvement in breast cancer–specific death rates year over year.
“These highlights coincide with significant therapeutic advances for HER2+ metastatic breast cancer over the past decade. We need to continue our research efforts to identify better treatments for our patients so we can continue to improve the prognosis of these patients,” said study author Jose Pablo Leone, MD, a medical oncologist with Dana-Farber Cancer Institute, Boston.
The study, which is based on an evaluation of data from the Surveillance, Epidemiology and End Results database, found factors associated with shorter survival included older age, Black race, lower income, and the presence of visceral or brain metastases. Long-term survival of more than 5 years was associated with younger age, White race, and higher income, but also having fewer metastatic sites and estrogen receptor (ER)/progesterone receptor (PR) positivity.
“We also found specific factors that were only associated with shorter overall survival, such as the presence of metastases in the brain, liver, or lung. The lack of metastasis in these sites was not associated with longer overall survival. In contrast, a lower number of metastatic sites, regardless of the location of those sites were associated with longer overall survival but not short-term survival,” Dr. Leone said.
A total of 63.3% of patients in the study survived less than 2 years while 37.8% lived 5 years or more, and 26.8% lived longer than 8 years. Factors associated with less than 2 years in overall survival were older age (odds ratio, 3.76), Black race (OR 1.5), nonductal nonlobular (OR, 4.64), brain metastases (OR, 2.95), liver metastases (OR, 1.98), lung metastases (OR, 1.56), ER/PR negativity (OR, 1.74), and lower income (OR, 1.62). Factors associated with longer survival of 5 years or more included younger age (OR, 2.85), White race (OR, 1.7), fewer metastatic organ sites (OR, 2.6), ER/PR positivity (OR, 1.27), and higher income (OR, 3.31).
Dr. Leone said that, while involvement of specific visceral sites (brain, liver, lung) was associated with shorter overall survival, the odds of living longer than 5 years was not associated with those sites. In contrast, the number of sites was associated with longer overall survival, but not shorter overall survival regardless of location. “While fewer number of metastatic sites were associated with higher odds of overall survival greater than 5 years, the number of metastatic sites was not associated with the odds of overall survival of being less than 2 years,” he said.
A limitation of the study included the retrospective nature of the study. “Treatment data are unavailable, so we cannot quantify the impact of various treatments on the odds of survival,” Dr. Leone said.
This study was not funded.