Breast cancer mortality rates fell by nearly 40 percent from 1989 to 2015—but racial disparities remain, according to a report published last week by the American Cancer Society (ACS).
For the study, researchers from ACS analyzed federal data sets to identify breast cancer incidence, mortality, screening, and survival rates in the United States from 1975 to 2015. The researchers also projected the number of newly diagnosed breast cancer cases for 2017.
The researchers found breast cancer mortality rates rose by 0.4 percent annually from 1975 to 1989, but then experienced a rapid decline from 1989 to 2015—ultimately decreasing by 39 percent from their peak, averting 322,600 breast cancer deaths among U.S. women. However, they noted that breast cancer continues to be the second-leading cause of cancer death among women in the United States. The researchers projected about 253,000 new cases of invasive breast cancer will be diagnosed in the United States this year, and more than 40,600 women will die as a result of the disease.
The researchers attributed the decline in breast cancer mortality to improvements in detection and treatments—such as adjuvant chemotherapy and more targeted therapies. However, they said such advancements have not addressed the racial and ethnic disparities in breast cancer death rates. According to the study, breast cancer death rates declined across racial and ethnic groups—including non-Hispanic whites, non-Hispanic blacks, Asian/Pacific Islanders, and Hispanics—from 2006 to 2015, but mortality rates from breast cancer continued to be higher among black women than among white women. In 2015, the mortality rate for black women was 39 percent higher than the rate for white women.
According to the study, part of the disparity is a result of the improvements in health outcomes experienced among women with hormone-receptor (HR) positive breast cancer after FDA in 1977 approved endocrine therapy with tamoxifen, which targeted HR-positive breast cancer. Among black women, the benefits were less pronounced, because fewer of them have HR-positive breast cancer, the researchers said. They added that black women are twice as likely as white women to be diagnosed with triple-negative breast cancers, which the report authors note is difficult to treat.
The researchers identified three states—Connecticut, Delaware, and Massachusetts—that they believe showed improvements in reducing racial disparities for breast cancer deaths.
According to the study, the majority of breast cancer diagnoses and breast cancer deaths occur among women ages 50 and older. In particular, the researchers found 81 percent of breast cancer cases are diagnosed among women 50 and older, and 89 percent of breast cancer deaths occur among these women. The researchers said the median age of breast cancer diagnosis for women overall is 62.
Carol DeSantis, director of breast and gynecological cancer surveillance research at ACS and the study's lead author, said the study shows "there is light at the end of the tunnel" for reducing racial disparities, because "some states are showing that they can close the gap."
However, Lee Schwartzberg, a medical oncologist at West Cancer Center, said current disparities are still "not acceptable." Schwartzberg said the difference in breast cancer mortality rates between ethnic and racial groups is a result of several factors, including economic and biological factors. For example, Schwartzberg said some "patients who get diagnosed with cancer … have difficulty making their appointments, like radiation every day for four or five weeks," because they cannot request time off from work.
Teal Holden, the vice president of ambulatory services at Memorial Hermann Health System, said, "Research shows that early detection may offer the greatest opportunity for full recovery." Holden added that "the most effective way to detect breast cancer at an early, curable stage is to have a clinical breast exam each year and an annual screening mammogram starting at age 40" (McGinley, "To Your Health," Washington Post, 10/3; Santana, Houston Chronicle, 10/3; DeSantis et al., CA: A Cancer Journal for Clinicians, 10/3).
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