Breast cancer risk is generally lower in younger women, with only about 6% of cases occurring in those under 40, and the risk significantly increases with age, peaking around the 70s before slightly declining in older age, showing that younger age is when breast cancer is less likely. While less common in young women, the cancer can be more aggressive, but early detection through self-awareness (as screening isn't routine under 40) is crucial for better outcomes.
Interestingly, before 49 years of age the estimated risk of developing breast cancer is 1/53 however, this rises to 1/43 for 50–59 years old and rises again to 1/23 for 60–69. Significantly, for women aged >70 this risk is the highest with a 1/15 chance of developing breast cancer [3].
The main factors that influence risk include being a woman and getting older. Most breast cancers are found in women who are 50 years old or older. Some women will get breast cancer even without any other risk factors that they know of.
Breast cancer in women
Rates of breast cancer are low in women under 40. About 4% of women diagnosed with breast cancer in the U.S. are younger than 40 [6]. Rates begin to increase after age 40 and are highest in women over age 70 (see Figure 2.1 below).
Overall, the average risk of a woman in the United States developing breast cancer sometime in her life is about 13%. This means there is a 1 in 8 chance she will develop breast cancer.
About 90% of cancers are caused by environmental and lifestyle factors, not genetics, including smoking, poor diet (red meat, fried foods), alcohol, sun exposure, pollutants, infections, obesity, and inactivity; only 5–10% are due to inherited genetic defects, with most cancers arising from lifestyle-induced genetic mutations. Tobacco alone accounts for about a third of cancer deaths, while diet, obesity, and inactivity contribute significantly, with controllable factors being key to prevention.
If you have a 20% lifetime risk (or higher) of developing breast cancer, you're considered “high risk”. Women with an average risk of breast cancer have a 10 to 12 percent chance of developing it in her lifetime.
Rates of breast cancer in the U.S. vary by race and ethnicity. Non-Hispanic white women and non-Hispanic Black women have the highest incidence of breast cancer (rate of new breast cancer cases) overall [336]. Hispanic women have the lowest incidence (see Figure 2.3 below) [336].
The 5 key warning signs of breast cancer often involve changes like a new lump or thickening, a change in breast size or shape, skin changes such as dimpling or redness, nipple changes like inversion or discharge, and persistent pain or swelling in the breast or armpit, though many symptoms can overlap, and you should see a doctor for any new or unusual breast change.
Among women with interval cancers, the mean time from the initial screening mammogram to a breast cancer diagnosis was 199 days (SD = 115 days) for invasive cancers and 164 days (SD = 118 days) for in situ breast cancers (data not shown).
Overall, women who get regular exercise have a 10%-20% lower risk of breast cancer than women who aren't active [139-146]. This benefit is seen most clearly in postmenopausal women, but study findings also show a benefit in premenopausal women [139-146].
The earliest stage of breast cancer, Stage 0 is non-invasive, meaning it hasn't spread outside of its original location in the breast tissue, and is highly treatable when detected early. If left undetected or untreated, however, it can spread into surrounding breast tissue.
You're exposed to a small amount of radiation during a mammogram. While the radiation exposure during a mammogram can increase the risk of breast cancer over time, this increase in risk is very small [5-8]. Learn more about radiation exposure during a mammogram.
Factors that may increase the risk of breast cancer include:
The Task Force now recommends that all women start getting screened for breast cancer every other year starting at age 40. Basically, it's a shift from recommending women start screening between the ages of 40 and 50 to recommending that all women start getting screened when they turn 40.
In the U.S., breast cancer mortality decreased by 40% since 1990 thanks, in large part, to the rising use of mammography. It's a preventative measure that works, if you use it. More women under the age of 40 are diagnosed with breast cancer than ever before. And it's often more deadly in younger women.
The most common sign of breast cancer is a lump or mass. It is usually hard, painless, and has uneven edges. Some lumps, however, can be soft and rounded. If you find one we recommend you contact your physician — a primary care doctor or a gynecologist — to have the lump evaluated.
These lifestyle choices, including smoking, drinking alcohol, and eating poorly may all raise your risk. Regular physical activity and maintaining a healthy weight are effective methods to lower your risk. This disease may also arise as a result of certain birth control methods and hormone replacement therapy.
Redness, rash or blotchiness of the breast. Some women report that it looks like a bug bite. Pain and/or soreness of the breast. Lump, thickening or dimpling of the skin of the breast.
10 tips for breast cancer prevention
Here are some tips:
A study published in Nature last fall suggests that breast cancer is slightly more common on the left side of the body than it is on the right. That same study also indicates that left-sided breast cancer is more aggressive and associated with poorer treatment outcomes.
However, only a few dietary factors appear to be related to breast cancer. Studies show [22,175-178]: Drinking alcohol is linked to an increased risk of breast cancer. Eating fruits and vegetables may be linked to a decreased risk of breast cancer.
Be mindful of what you eat and drink
Eating a plant-based diet, limiting how much red meat you eat and limiting alcohol consumption may help prevent certain cancers. Alcohol increases the risk of various types of cancer, including breast, colon, lung, kidney and liver cancers.
Women in the U.S. have a 1 in 8 (or about 13%) lifetime risk of getting breast cancer [5]. This means for every 8 women in the U.S., 1 will be diagnosed with breast cancer during her lifetime.