Breast cancer rates are rising. Here’s how to lower your risk.

But the disease remains rare in younger women. The 10-year probability of being diagnosed with breast cancer at 30 is 1 in 198, or 0.5 percent, compared with 1 in 62, or 1.6 percent, at age 40, and 1 in 41, or 2.5 percent, at 50.

There were also significant disparities by race. Asian American/Pacific Islander women had the fastest increase in both age groups (2.7 percent per year for women younger than 50 and 2.5 percent per year for those over 50). But it is the top killer for Black women, who are 5 percent less likely to get breast cancer than white women but have a 38 percent higher chance of dying from it.

Why is the incidence of breast cancer rising among young women?

Experts don’t have clear answers, but there are plenty of theories. Several pointed to the obesity epidemic as a possible cause. Dr. A. Gwen Caffrey, an oncologist at UMass Memorial Medical Center and HealthAlliance-Clinton Hospital, said high body mass index is associated with early menarche, which is a risk factor in developing breast cancer. She also noted that alcohol is carcinogenic and pointed to the rise of “craft beer culture” and other factors that influence the amount of alcohol consumed by young people.

Dr. Harold J. Burstein, a medical oncologist and clinical investigator at the Dana-Farber Cancer Institute’s Breast Oncology Center, noted that women are having fewer children, having them at later ages, and spending less time nursing, all of which could increase the risk of breast cancer on a population level.

Whatever the cause, there is an urgent need to fund the research needed to figure it out, said Dr. Ann Partridge, founder and director of the program for young adults with breast cancer at Dana-Farber. Younger women who are diagnosed with breast cancer, she said, tend to get more aggressive types of cancer, which often require more aggressive therapies.

“And even with that, they on average do worse than older women with the same disease,” she said.

What can women do to lower their risk?

Smoking cessation, a healthy diet, and steering clear of alcohol can reduce risk, as can regular exercise, experts said.

Early screening and an understanding of familial risk can also make a big difference. In April, the US Preventive Services Task Force, an independent panel of experts funded by the US Department of Health and Human Services, lowered the recommended age for regular mammography screening from 50 to 40.

But women with a significant family history of breast cancer can get genetic counseling and start mammograms or other imaging tests at even earlier ages to increase the chances of early detection.

Dana-Farber has an online tool called Assess Your Risk that is a good place to start, said Partridge.

For high-risk patients, there are medications that can significantly reduce the risk of some breast cancers. Those include a once-a-day pill, Tamoxifen, that when taken for three to five years, may reduce the risk of breast cancer by roughly half, Caffrey said.

If you’re too young for a mammogram, how can you improve your odds of early detection?

Young women need to “ask questions and be their own best advocates,” said Partridge.

“Because while breast cancer in young women is increasing, it’s still rare, but it does happen,” she said. “No woman should be told, ‘You’re too young to get breast cancer, we’re just going to watch that lump.’ We need to really educate women and providers on how to make sure that people are getting the care they need should they develop symptoms or signs of a breast cancer.”

Women of all ages should also get to know their own breasts so they can quickly notice changes.

“That goes beyond just the idea of a breast self-exam,” Caffrey said. “You should know, is one breast larger than the other? Are you somebody with lumpy breasts or not lumpy breasts? Are your nipples inverted or everted? Those are all normal things and normal variations from one person’s body to another. But when you are aware of what your breasts look like, you’re that much more able to identify a change.”

The most common change associated with breast cancer, she said, is a hard, painless lump that doesn’t fluctuate with menstrual cycles, doesn’t go away on its own and just continues to grow. Other changes to be on the lookout for are changes in size, changes in symmetry, changes in the shape of the nipple, the contour of the breast, new breast swelling, and unusual or bloody nipple discharge.

“Those would all be things that should not wait for a routine visit or routine screening study,” she said. “Those would be reasons to reach out to your doctor to be looked at right away.”

How much should you worry about consuming plastic or reading makeup ingredients to avoid toxins?

Several clinicians said that is a “hot topic” but noted the jury is still out.

“There’s really not a lot of hard data that antiperspirant, hair products, makeup, or facial products affect the risk of breast cancer,” said Burstein. “I think women can use those products as they wish without undue concern.”

What about women with dense breast tissue?

By some estimates nearly half of all American woman have dense breasts, which makes it harder to detect abnormalities on mammograms and is associated with a greater risk of developing breast cancer. Earlier this month, the Food and Drug Administration implemented a new rule requiring mammography facilities to notify women if they have dense breasts, so that they can consider additional imaging tests.

Women with dense breasts should continue with their annual mammogram, Caffrey said. But they should also consider supplemental imaging options, including ultrasounds, and MRIs, which are often covered by insurance for women at higher risk.

Partridge also often advises patients with dense breast tissue, which is far more common in the younger patients she treats, to undergo additional imaging. Though she notes there are drawbacks: Because the scans are so detailed, they are far more likely to have false positives that require follow-up scans, and even biopsies.

Adam Piore can be reached at [email protected].