But, there is some good news.
Key Takeaways
- A new study found that stage 4 breast cancer is on the rise in the United States.
- But, thanks to improvements in treatment, survival rates are also increasing.
- Breast Cancer Research Foundation investigator Dr. Jose Pablo Leone explains what you need to know about the latest research.
A recent study found that rates of stage 4 breast cancer, also known as metastatic breast cancer, are rising in the United States. The new findings, from Breast Cancer Research Foundation (BCRF) investigator Dr. Jose Pablo Leone, were published in the journal JAMA Network Open, and point to some surprising changes in the metastatic cancer landscape.
Dr. Leone and his team found that the incidence rate of stage 4 breast cancer increased from 9.5 cases per 100,000 women in 2010 to 11.2 cases per 100,000 women in 2021. The proportion of stage 4 cases within all breast cancer diagnoses also rose, from 5.6 percent in 2010 to 6.0 percent in 2021. The median age at diagnosis was 60 overall and 63 for patients with stage 4 disease.
Increases in stages I to III happened across all tumor subtypes, including hormone receptor (HR)-positive/HER2-negative, HR-positive/HER2-positive, HR-negative/HER2-positive, and triple-negative disease.
Dr. Leone, who also studies male breast cancer with support from BCRF, said the results of the study surprised him.
“The increase in incidence is higher than I had expected,” he says. Historically, incidents of stage 4 have been a smaller portion of disease.
But there is good news: Thanks to improved treatments for metastatic breast cancer in recent years, survival rates are also increasing for HR-positive/HER2-negative, HR-negative/HER2-positive, and HR-positive/HER2-positive breast cancer. The study showed about a 1 percent reduction in risk of death per year for HR+/HER2- breast cancer, about a 3 percent reduced risk of death per year for HR+/HER2+ breast cancer (which was highly significant), as well as about a 3 percent reduction in risk of death per year for HR-/HER2+ breast cancer (also statistically significant). The numbers improved every year, so patients diagnosed more recently tend to survive longer than those diagnosed earlier, based on the data.
Dr. Leone said that additional studies are ongoing to examine the causes of these increases. However, he hypothesizes that they may include:
- The natural history of breast cancer (how the cancer develops and changes over time)
- Changes in breast cancer screening (more sophisticated imaging may lead to more cancers being found)
- Environmental factors that affect both sexes, all ages, and all racial groups
Citing a 3.7 percent annual increase in male breast cancer per year over the same period, Dr. Leone theorizes that the contributors are not specific to men or women, underscoring the critical need for more research across the sexes.
Getting to the root of the increases will take a multipronged approach that focuses on catching cancer before it spreads, he adds. One of the challenges is that breast cancer is so common, making it hard to identify isolated causes—there may be many contributing factors.
“We want to do more studies on this issue to try to understand better the heterogeneity of the impact on the increasing incidence,” he says.
Dr. Leone said that BCRF’s support has been integral to his studies.
“It is thanks to the support from BCRF that I have the time to do many of the things that I do,” he says. “It allows us to be able to think creatively about issues that we’re seeing in clinic, in the news, and how to better serve the population.”
