There are about 3.5 million women living with breast cancer in the U.S., including those newly diagnosed, long-term survivors, and those experiencing a recurrence. According to a new National Cancer Institute (NCI) study, about 4 percent of them—roughly 154,000—have metastatic, or stage four, breast cancer: Tumors have spread from the breasts to distant sites in the body, such as the brain or liver.

Until recently conventional wisdom has been that women with metastatic breast cancer were essentially looking at a death sentence, with a five-year survival rate of only 22 percent, according to the American Cancer Society.

But this new research tells a more optimistic story. It reveals that the number of women in the U.S. living with metastatic breast cancer is growing and that survival rates are improving, according to the new study, published today in the journal Cancer Epidemiology, Biomarkers & Prevention.

When researchers analyzed a registry of government data that tracks cancer cases around the country, they found that the five-year survival rate of these women younger than 50 doubled from 18 percent between 1992 and 1994 to 36 percent between 2005 and 2012. Median survival times also increased, from 22 months to almost 39 months for women younger than 50, and from 19 months to almost 30 months for women diagnosed between ages 50 and 64.

“We found that a meaningful number of women actually lived many years after an initial diagnosis of metastatic breast cancer—more than 11 percent of women under age 64 survived at least a decade,” says study author Angela Mariotto, Ph.D., chief of the Data Analytics Branch of the Division of Cancer Control and Population Sciences at the NCI.  

Why Outcomes Are Improving

“This study confirms what anecdotally we’ve known for a long time—that women with metastatic disease are living longer, with a better quality of life,” says Harold Burstein, M.D., Ph.D., associate professor of medicine at Harvard Medical School and an oncologist at the Dana-Farber Cancer Institute in Boston. That's especially true for younger women, and for women with the most aggressive and virulent cancers, who used to have few treatment options. 

There are a few reasons: 

More effective drugs. Medications such as trastuzumab (Herceptin) significantly improve long-term survival of patients with HER2-positive breast cancer, one of the most virulent forms of the disease, especially when used in combination with other drugs. There are also new drugs on the market, such as palbociclib (Ibrance), approved by the FDA in 2015 to treat post-menopausal women with advanced breast cancer, which in clinical trials has doubled survival rates from 10 to 20 months.

“Suddenly there’s a whole subset of patients with a previously ominous prognosis who are now doing incredibly well long-term, staying in remission for five, seven, even 10 years,” says Elisa Port, M.D., chief of breast surgery at Icahn School of Medicine at Mount Sinai and director of the Dubin Breast Center in New York City.

Fewer side effects. Newer chemotherapy drugs to treat breast cancer, such as eribulin (Halaven), not only increase overall survival rates but also have fewer side effects, such as nausea, vomiting, hair loss, fatigue, and neutropenia (low white-blood-cell count), Burstein says.

“It’s a lot easier for patients to stick with treatments if they’re a lot less noxious,” he says. These treatments are also less likely to cause bone loss, another side effect of both cancer and aggressive treatments. “A decade ago, women with metastatic breast cancer were dying not only from the cancer itself but from . . . the treatment,” Burstein adds. “We rarely see that anymore.”

Earlier diagnoses. “We are actually finding metastatic disease earlier because we have better imaging tests available than we did a decade or two ago—a patient will go to the ER for shoulder pain and get a CT scan that shows lung metastases,” says Anne Schott, M.D., an oncologist specializing in breast cancer at the University of Michigan in Ann Arbor.

Impact on Patients

Some women have metastatic breast cancer when they’re first diagnosed (called de novo metastatic breast cancer), but about 75 percent of the time it shows up months or years after a woman has finished treatment for early or locally advanced (stage 1, 2, or 3) breast cancer, according to the NCI study.

Lifestyle changes might help reduce the risk of recurrence. Exercise, for example, can help reduce that risk by 40 percent, concluded a review published in FebruarySome studies show that being overweight or obese is associated with an elevated risk of relapse, and other research shows that eating a low-fat diet and plenty of fruits and vegetables is linked to a lower risk. (The American Cancer Society recommends eating at least 2½ cups of vegetables and fruits daily, substituting whole grains for refined grains, and limiting red and processed meats as well as alcohol.)

For women with early stage, estrogen-receptor-positive breast cancer, taking tamoxifen for 10 years (not just five) can also reduce risk, Port says. Recurrence rates are 21 percent among women who take it for 10 years, compared with 25 percent among women who take it for just five.

If you are diagnosed with metastatic cancer, it’s important to find out from your oncologist exactly what type of cancer you have (estrogen-positive or -negative, HER2-positive, triple-negative), as well as the cancer biomarkers. These details will help guide your treatment.

“It’s important to realize that although metastatic breast cancer can’t be cured, we now have treatments that can substantially improve both length and quality of life,” Burstein says.