Breast Cancer Risks and Prevention

A Sutter Health network expert discusses why some women are at higher risk of breast cancer and recommendations for yearly mammograms.

Contributor

Harriet Borofsky, M.D.

Mills-Peninsula Medical Center

It seems everyone knows a woman who has been diagnosed with breast cancer. And no wonder. Among women in the United States, breast cancer is the second most common cancer diagnosis (after skin cancer) and the second leading cause of cancer-related deaths (after lung cancer).

In 2019, about 268,600 women will be diagnosed with invasive breast cancer, according to the American Cancer Society. About 63,000 more will be diagnosed with non-invasive breast cancer (cells that are abnormal but have not invaded nearby tissues, also known as ductal carcinoma in situ). About 41,760 women will die of breast cancer this year.

Young woman smiling

There’s been some good news in recent years. Breast cancer incidence rates in the U.S. began decreasing in the year 2000, after increasing for the previous two decades. The American Cancer Society found that from 2002 to 2003, there was a near seven percent drop in new cases of breast cancer, most likely due to fewer women using hormones to address symptoms of menopause. And death rates from breast cancer dropped 40 percent from 1989 to 2016, likely due to early detection through screening and better, targeted treatments and therapies.

One more bit of good news: When breast cancer is diagnosed at an early stage and small size (before it has spread to lymph nodes, nearby structures or other places outside the breast), the five-year survival rate is 99 percent.*

* Source: American Cancer Society

Breast Cancer Risk Factors

Why do some women get breast cancer and others don’t? We don’t know. “Researchers have identified several risk factors that can make a woman more likely to develop the disease, but all women are at risk for breast cancer. That’s why we do mammogram screenings for all,” says Harriet Borofsky, M.D., medical director of the Mills-Peninsula Women’s Center. “One woman can have several risk factors and never develop breast cancer, while another might seem to be at very low risk, and still get the disease.”

Some of the currently known factors that can raise your risk:

Being a Woman and Getting Older — About two-thirds of all invasive breast cancers are diagnosed in women over age 55. While many reports note that one in eight U.S. women will be diagnosed with breast cancer, it’s important to understand that that is over a total lifetime. The average woman’s risk over the next decade is much lower. If you’re now age 40, for example, you have a 1 in 68 chance of being diagnosed in the next ten years. At age 50, 1 in 42; at age 60, 1 in 28; and at age 70, 1 in 26.
Genetics — Women who inherited a BRCA1 or BRCA2 genetic mutation have a much higher than average lifetime risk of developing breast cancer, ranging from 45 percent to as high as 80 percent.
Family History — “Having one first-degree relative — a mother, sister or daughter — with breast cancer about doubles a woman’s risk,” Dr. Borofsky says. “Having two first-degree relatives raises your risk about threefold.”
Personal History — If you’ve been diagnosed with cancer in one breast, you have a higher-than-average risk of developing a new cancer in either breast. You’re also at higher risk if you have dense breasts or had radiation to the chest as a child or young adult.
Hormonal History — You’re at higher risk if you started menstruating early (before age 12) or went through menopause later than most (after age 55).
Childbearing History— If you’ve had no children by age 30, you’re at higher risk for breast cancer.

While you can’t change getting older or your family history, there are several known risk factors you can address to try to lower your risk of breast cancer.

Keep your weight in check. Obesity is linked to breast cancer.
Drink alcohol only in moderation. Population studies have found that people who drink alcohol have a higher risk of breast cancer.
Be physically active. Many studies show that physically active women have a lower risk of breast cancer.
Don’t smoke. While it’s not proven that smoking raises your risk of breast cancer, research shows it does raise your risk of dying if you get breast cancer.
Avoid certain types of hormone replacement therapy after menopause. Long-term HRT with certain estrogen-progestin combinations has been found to increase breast cancer.

Breast Cancer Screening Exams

New advances in mammography such as digital breast tomosynthesis, also known as 3D mammograms, are maximizing the benefits of screening by improving breast cancer detection and overall accuracy. They also reduce false positives and unnecessary recalls.

The American Cancer Society recommends that women have yearly mammograms starting at age 45 (they say women should have the choice to start at age 40). Other organizations say all women should have mammograms at age 50, and should have the choice to start at 40. However, Dr. Borofsky says basing mammogram recommendations solely on a woman’s age can be problematic. “Breast cancer for women in their 40s is not insignificant. It accounts for at least 20% of breast cancers in women with the most potential years of life and with more aggressive tumors. Screening for women in their 40s needs to be encouraged and supported.”

If you are at very high risk of breast cancer, due to factors such as a genetic mutation or a strong family history of breast cancer, your doctor might suggest you also have regular MRI exams of your breasts.

Whether a woman should have regular breast exams from a doctor and do breast self-exams is also up to her and her doctor, and will depend, in part, on her personal risk of breast cancer.

“Most important is knowing what’s going on in your own body, and being aware of any changes,” Dr. Borofsky says. “I see women all the time who found lumps in their breasts. They knew something was different and brought it to our attention.”