A person’s risk of developing breast cancer changes as they get older. Overall, approximately 12.9 percent of women in the United States — about 1 in 8 — are diagnosed with breast cancer at some point over the course of their life, according to the National Cancer Institute (NCI). However, this diagnosis is more likely to come in their later years.

Other breast cancer risk factors can increase a person’s chances of developing cancer at an early age. Knowing when your breast cancer risk increases can help you understand when to start taking extra protective measures, such as getting mammograms.

Breast Cancer Risk Increases Over Time

The older a person gets, the more likely they are to develop breast cancer. In general, children and teens don’t get breast cancer. About 90 percent of breast cancer diagnoses occur in women aged 45 or older. Additionally, about half of women with breast cancer are at least 63 years old when they are diagnosed.

According to the NCI, during each decade of life, a woman’s breast cancer risk increases.

• A 30-year-old woman has a 0.49 percent chance of developing breast cancer in the next 10 years.
• A 40-year-old woman has a 1.55 percent chance of developing breast cancer in the next 10 years.
• A 50-year-old woman has a 2.4 percent chance of developing breast cancer in the next 10 years.
• A 60-year-old woman has a 3.54 percent chance of developing breast cancer in the next 10 years.
• A 70-year-old woman has a 4.09 percent chance of developing breast cancer in the next 10 years.

These numbers account for all women across the United States. Many other risk factors affect whether any individual will develop breast cancer, so each person’s risk may be higher or lower than what these numbers show. It is also unclear whether these figures are affected by a difference in access to health care resources between individuals.

Why Does Age Affect the Risk of Breast Cancer?

A cell turns cancerous when it develops gene changes or mutations that make it grow too quickly or stop the cell from healing damage. The older a person gets, the more gene changes their cells have and the less likely their body is to fight off cancerous cells.

One reason cancer most often develops in older adults is that gene mutations build up over time. Throughout a person’s life, they are exposed to many things that change their cells’ DNA. Cells are able to fix a lot of these gene mutations, but some mutations persist. After many years, a person’s cells contain numerous gene changes, the combination of which may lead to cancer. Some mutations make a cancer cell able to establish its own blood supply, to break through tissue boundaries, or to travel and survive in different organs. Other mutations may give cancer cells the capacity to mask themselves from the immune system.

The body isn’t as well-protected against cancer during a person’s later years. Normally, the immune system helps detect and kill cancer cells. However, a person’s immune system becomes less effective over time, giving cancer cells a greater chance of surviving in older adults.

How Age Affects Other Breast Cancer Risk Factors

Certain other factors can affect breast cancer risk. These may include race or ethnicity, genetics, weight, alcohol consumption, tobacco smoking, and amount of exercise. A person’s ages at their first period, first childbirth, and menopause also affect their risk.

Race or Ethnicity

Risk of breast cancer can depend on race or ethnicity. In the U.S., across all ages, white women tend to develop breast cancer at the highest rates, according to the NCI. Native American women get breast cancer at lower rates than other groups.

However, when researchers look at breast cancer rates by age, they see different patterns. In the U.S., younger women who are Black, Hispanic, or Asian develop breast cancer more often than younger white women, according to a study from JAMA Surgery. However, older women who are Black, Hispanic, or Asian are less likely to be diagnosed with breast cancer than older white women.

Women of different races or ethnicities get breast cancer at different rates within different age groups, according to NCI data:

• White women who are 30 years old have a 0.48 percent chance of developing breast cancer in the next 10 years. White women aged 60 have a 3.64 percent chance.
• Black women who are 30 years old have a 0.53 percent chance of developing breast cancer in the next 10 years. Black women aged 60 have a 3.28 percent chance.
• Asian or Pacific Islander women who are 30 years old have a 0.44 percent chance of developing breast cancer in the next 10 years. Asian or Pacific Islander women aged 60 have a 2.87 percent chance.
• Native American and Alaska Native women who are 30 years old have a 0.29 percent chance of developing breast cancer in the next 10 years. Native American and Alaska Native women aged 60 have a 2.22 percent chance.
• Hispanic women who are 30 years old have a 0.4 percent chance of developing breast cancer in the next 10 years. Hispanic women aged 60 have a 2.86 percent chance.

Genetics and Family History

Up to 1 in 10 breast cancer cases may be caused by gene changes that are passed down within families. Usually, gene changes that cause breast cancer affect the BRCA1 or BRCA2 genes. When these genes don’t work properly, damage can build up within breast cells, making them grow out of control.

People who have changes in their BRCA genes have a higher risk of developing some types of cancer, including both breast and ovarian cancer. They are also likely to develop these cancers at a younger age.

For people without BRCA gene changes, the average age at which breast cancer develops is 63. Studies have shown that women with BRCA1 gene mutations are most likely to develop breast cancer between the ages of 41 and 50. Women with BRCA2 gene mutations most often develop breast cancer between the ages of 51 and 60.

Age at First Period, First Childbirth, and Menopause

The longer a person’s breast cells are exposed to the hormone estrogen, the higher their breast cancer risk. The role of the hormone progesterone is less clear. The ovaries start producing these hormones during puberty. This means that women who go through puberty before the age of 12 have an increased chance of developing breast cancer. Likewise, the ovaries stop making estrogen and progesterone at menopause. Women who go through menopause after the age of 55 are at higher risk of breast cancer.

There is a complicated link between breast cancer and pregnancy. A woman’s risk of developing breast cancer increases in the short term after giving birth — she is more likely to be diagnosed within 10 years of having her first child. However, after this time period, women who have had children have a lower risk of breast cancer than women who have never given birth.

Additionally, the younger a woman is when she has her first child, the more her breast cancer risk drops. A woman who has her first child after she turns 35 is 40 percent more likely to be diagnosed with breast cancer than a woman who has her first child before she turns 20.

Protecting Against Breast Cancer

There is no guaranteed way to prevent breast cancer. You also can’t change certain risk factors such as age, race, inherited gene changes, or family history. However, there are some ways you can reduce your risk.

Many lifestyle changes or habits can help lower your risk of developing breast cancer. These include:

• Lowering your alcohol consumption
• Avoiding smoking cigarettes
• Eating a more balanced diet
• Getting more physical activity
• Maintaining a healthy weight

Making lifestyle changes to reduce cancer risk may be especially helpful in your middle-aged years. Your risk of developing certain types of cancer increases between the ages of 45 and 65. Focusing on health at this stage can help reduce your cancer risk later on.

When To Start Getting Mammograms

A mammogram is a type of X-ray that allows doctors to see changes in your breast tissue. A mammography is an important tool for breast cancer screening. Early detection often leads to a better outlook.

Many experts, including those at the American Cancer Society, recommend that women who have an average risk of developing breast cancer get their first mammogram between the ages of 40 and 44. Mammograms should be repeated each year while you are between 45 and 54 years old. After this point, you can undergo mammograms every two years.

Some women who have a higher-than-average risk of breast cancer may need additional screening measures. This group includes those with a family history of breast cancer, BRCA gene mutations, or a history of radiation therapy. If you are at high risk, your doctor will likely recommend beginning screening earlier, often when you turn 30 years old. Screening for high-risk women involves a mammogram as well as an MRI scan.

Talk to your health care team about your own breast cancer risk. Your doctor can help you understand any risk factors and recommend when to start regular screening for breast cancer.

Talk With Others Who Understand

MyBCTeam is the social network for people with breast cancer and their loved ones. On MyBCTeam, more than 53,000 members come together to ask questions, give advice, and share their stories with others who understand life with breast cancer.

Are you worried about your risk of developing breast cancer? Share your experiences in the comments below, or start a conversation by posting on MyBCTeam.