Better screening has led to earlier diagnosis and an improvement in breast cancer survival.
The National Cancer Institute recently reported that even though the number of women diagnosed with breast cancer has been going up since 2010, the number of deaths from breast cancer has been steadily dropping.
That may seem like a contradiction, but a 2024 study from Stanford University and the National Institute of Health explains that deaths from breast cancer in women have dropped by almost 60 percent since 1975.
The study found that the biggest reason for the decrease in breast cancer deaths (58 percent) is due to better screening. Better screening includes new technology as well as recognition of the importance of screening by women and their primary care providers.
Mammograms have been recommended since 1976 by the American Cancer Society (ACS). One major improvement in mammography technology has been a new type of mammogram called digital breast tomosynthesis, or 3D mammography. This type of screening is better at finding early cancers in women with dense breasts. Another innovation has been the increased use of MRI breast imaging, which is more likely to detect early cancers in women at high risk for breast cancer.
According to the ACS, women ages 40 to 44 should have the choice to start annual breast cancer screening with mammograms if they wish to do so. Women ages 45 to 54 should get mammograms every year. Women ages 55 and older should switch to mammograms every two years, or can continue yearly screening.
Screening should continue if a woman is in good health and is expected to live 10 more years or longer. Women with dense breasts may benefit from the newer 3D mammogram in place of the older mammogram. Women at high risk should get a mammogram and breast MRI every year, and the ACS suggests they begin their screening at age 30 or an age recommended by their health-care provider and continue for as long as they are in good health.
You are considered at high risk for breast cancer if you have had breast cancer in the past, have a strong family history of breast cancer, or inherited a specific gene mutation that can increase your risk for breast cancer, such as BRCA.
The 2024 study found that 25 percent of reduced deaths were due to improved treatment for early-stage breast cancer (stages 1 through 3, which means the cancer is confined to the breast and to nearby lymph nodes.) Twenty-nine percent of reduced deaths were due to better treatment for late-stage stage breast cancer, which was a surprise to the research team. Late-stage cancers, also called recurrent or stage 4 cancers, are not curable, but new treatments are helping women live longer. The study found that women with stage 4 cancer in 2000 had an average survival of less than two years. In 2019, the survival time was over three years.
Although surgery is still the mainstay of treatment, understanding the biology of different types of breast cancer has led to improved treatment and longer survival. You may have seen commercials on TV for new cancer treatments using terms like ER, PR, and HER2 positive or negative cancers. These are proteins that inform doctors about the biology of a breast cancer and allow them to determine the best type of treatment. This type of treatment is called targeted therapy, and has led to better survival. The status of these proteins can be tested only when cancer cells are removed with a biopsy or surgery.
Estrogen receptors (ER) and progesterone receptors (PR) are proteins on cancer cells that bind to the female hormones estrogen and progesterone, causing cancer cells to grow. About 75 percent of cancers are positive for ER or PR, which you would think would make the cancers grow faster, but having ER- or PR-positive cancer can be advantageous. They tend to grow more slowly, and drugs are available to target ER and PR and treat the cancer. Hormone receptor-positive cancers can be treated with drugs that block or lower estrogen.
The other important protein doctors want to know about is HER2, which is expressed in 15 to 20 percent of breast cancers. Like the hormone receptors, HER2 helps breast cancers grow, but unlike the hormone receptors, HER2 positive cancers grow more quickly. However, HER2 positive cancers have the benefit of responding to a drug called Herceptin, which blocks HER2.
The new study, Analysis of Breast Cancer Mortality in the US: 1975 to 2019, was published in the January 2024 edition of the American Medical Society journal JAMA. The researchers say their analysis is important because it helps cancer researchers and clinicians know what is working and where to focus future efforts and resources. For women, the results strongly support following the screening guidelines.
This analysis also supports the importance of understanding the biology of your cancer. The results will lead to the best treatment approach and outcomes. All breast cancers should be tested for hormone receptor status, and invasive breast cancer should also include HER2 testing. This is the standard of care and important for treatment planning. If you are diagnosed with breast cancer and have questions regarding your diagnosis or plan of care, it is reasonable to seek a second opinion with a breast cancer specialist. It is also important for women with advanced cancer to undergo repeat biopsy to recheck receptor status, which can change over time.
