Breast cancer rates — the second leading cause of cancer death among U.S. women — rose 1 percent annually from 2012 to 2021, and even more steeply among women under 50 and Asian American/Islander women. Pacific of all ages, according to American Cancer Society report published on Tuesday.
The biennial report is among the most comprehensive and detailed studies of breast cancer incidence in recent years. One in 50 women in the US will develop invasive breast cancer by age 50, the authors said, based on National Cancer Institute calculations.
The steepest increases in young adults by age over the decade were among women in their 20s, whose rate rose by about 2.2 percent per year, although the absolute risk remains very low, at about 6.5 per 100,000 women.
Among Asian American/Pacific Islander women, who also historically had a low prevalence of the disease, rates rose 2.7 percent annually among those younger than 50 and 2.5 percent annually among older women .
Cancer is generally thought of as a disease of aging, and that hasn’t changed: The vast majority of breast cancer cases and deaths still occur in older women. But the new study is one of several documenting an alarming rise in delinquency among younger Americans.
These so-called early-onset cancers pose special challenges. Striking in early adulthood or middle age, they tend to be aggressive, but are often missed because they are unexpected and routine screenings are aimed at older adults.
That has changed somewhat. Earlier this year, the US Preventive Services Task Force lowered the age for starting mammograms to 40 from 50, reversing an earlier decision to raise the screening age. The American Cancer Society recommends starting annual mammography at 45 for average-risk women, with an option to start at 40.
Despite the increase in incidence, breast cancer deaths have declined, falling by about 10 percent over the past decade and by 44 percent over the past three decades, due to improved screening and treatments.
However, the benefits have not accrued equally to all women, according to the report, which was published in CA: A Cancer Journal for Clinicians.
Survival rates did not change at all for Native American and Alaska Native women. Breast cancer remains the leading cause of cancer death among black women, who have a 38 percent higher death rate than white women.
Black women are more often diagnosed with certain types of tumors that are more difficult to treat. A recent Mass General Brigham study found that Black women are also more likely than white women to die from all types of breast cancer, suggesting that other factors play a role, such as delays in diagnosis and difficulty finding early quality care.
“The bottom line is that we need to improve access to high-quality screening and high-quality treatment for all women of color, especially black and Native American women,” said Rebecca L. Siegel, an epidemiologist at the American Cancer Society and senior editor. of the exhibition. “We need to extend this progress to all women.”
About 310,720 new cases of invasive breast cancer will be diagnosed in U.S. women this year, including 13,180 cases in women under 40 and 37,650 in women in their 40s, the paper estimated. Additionally, 56,500 cases of non-invasive ductal carcinoma in situ will be diagnosed in women of all ages.
An estimated 42,250 women will die from breast cancer, according to the study. About 2,790 cases will be diagnosed in men and 530 will die from it.
The incidence of breast cancer increased by 1 percent annually overall from 2012 to 2021. But women in their 20s, 30s and 40s saw a 1.4 percent annual increase in incidence, while the increase among women in their 50s and above was more modest, at 0.7 percent each year, the report found.
Diagnosis often takes longer in younger women, leading to delays in treatment and more advanced disease.
After Traci Delaney discovered a hard mass in her right breast, her insurance initially denied a CT scan ordered by her doctor. Ms Delaney, 34, said she herself did not feel a particular urgency because she was young and had no family history of breast cancer. (In fact, most women diagnosed with breast cancer do not have cancer in their family.)
“The biggest thing I’ve realized through this whole process is that there’s no age limit to it,” said Ms. Delaney, who lives in Los Angeles and is in remission after being treated last year with chemotherapy, radiation and surgery. for Stage II breast cancer. “Maybe it used to exist, but I really feel like it doesn’t exist anymore.”
It took even longer for Jeanelle Adams, 36, who is black and Puerto Rican, to be diagnosed with triple-negative breast cancer, a subtype that is especially difficult to treat because it is not driven by estrogen, progesterone or another hormone, the human epidermal growth factor 2.
Her first symptoms were unusual: a rash on the left breast, which had a dimpled (“orange-like”) appearance and nipple discharge. Doctors thought it was eczema and it took Ms Adams two years to get the correct diagnosis, even though she was convinced something more serious was going on.
Like many other women, Ms. Adams, who is married and lives in Northern New Jersey, does not have the typical risk factors. She has a 10-year-old daughter whom she breastfed for more than two years. she eats lots of vegetables, has always been physically active and is not overweight.
He suspects environmental factors are at play, though the research is sparse. “I work out all the time, I don’t put chemicals in my hair,” she said.
Among women of all ages overall, localized cancers — invasive tumors that have not spread beyond the breast to other parts of the body — accounted for most of the increase in incidence.
Most of the increase was in tumors fueled by the hormones estrogen or progesterone. Among women under 50, rates increased for diagnoses at every stage of cancer.
Changes in women’s reproductive lives are thought to be partly driving the increase, said Dr. Ahmedin Jemal, co-author of the report and senior vice president of surveillance and health equity at the American Cancer Society.
More women are delaying childbearing and having fewer or no children. Many do not breastfeed, which is seen as protective. Early menopause is a risk, as is late menopause.
All of these factors increase a woman’s exposure to the body’s estrogen and progesterone, hormones produced by the ovaries that can stimulate cell growth.
Obesity, which has become more common among Americans, also increases the chances of breast cancer for postmenopausal women age 50 and older. Physical activity and a healthy diet may help prevent the disease, experts say, while drinking and binge drinking increase the risk, accounting for more breast cancer cases than obesity, Ms. Siegel said.
Much less is known about the role that environmental factors may play, including the effects of hormone-mimicking chemicals such as phthalates (used in many perfumes and personal care products) and leached from food packaging.
Dani Alderman, 31, who lives in New York, discovered at 27 that she had inherited a genetic mutation that increased her risk of breast and ovarian cancer. She began getting regular check-ups, but doctors assured her that, even with her mutation, the risk was very low before the age of 30.
A week before her 30th birthday, however, a CT scan showed what turned out to be cancer.
“It’s really worrying,” Ms Alderman said. “I have the gene, but something causes the gene to be expressed. I exercise five days a week, I don’t really drink alcohol and I eat healthy. Is it microplastics? Processed foods? I think there must be something in the environment.”
