Breast cancer can sometimes run in families, a form known as hereditary breast cancer. The most common cause of hereditary breast cancer is mutations in the BRCA1 or BRCA2 genes.
Among people assigned female at birth, breast cancer is second only to some types of skin cancer in prevalence. According to the American Cancer Society, the average lifetime risk of developing breast cancer in this group is about 13%. However, certain genetic factors can increase this risk for some individuals.
This article explores hereditary and genetic risk factors for breast cancer, as well as screening guidelines for those at higher risk.
Genetic and Hereditary Factors in Breast Cancer
Cancer is fundamentally a genetic disease, caused by mutations in DNA that allow cells to grow uncontrollably. Most of these genetic changes occur during a person’s lifetime and are known as somatic mutations. Somatic mutations can result from aging or environmental and lifestyle factors.
Hereditary breast cancer, on the other hand, occurs when mutations associated with cancer risk are passed down from a parent. Roughly 5–10% of breast cancers are hereditary.
The most common hereditary cause involves BRCA gene mutations. People with BRCA1 or BRCA2 mutations have up to a 70% chance of developing breast cancer by age 80. These mutations also increase the risk of:
Developing breast cancer at a younger age
Cancer in both breasts
Other cancers, including ovarian and pancreatic cancers
A BRCA mutation can be inherited from either parent, with each child of a parent carrying the mutation having a 50% chance of inheriting it. It is also possible for breast cancer to run in families without identifiable BRCA or other known mutations. Research continues to uncover additional inherited risk factors.
Other Genes Linked to Hereditary Breast Cancer
Besides BRCA1 and BRCA2, less common genetic mutations can also raise breast cancer risk. Some are associated with rare hereditary syndromes:
PTEN → Cowden syndrome
TP53 → Li-Fraumeni syndrome
CDH1 → Hereditary diffuse gastric cancer; increases risk of lobular breast cancer
STK11 → Peutz-Jeghers syndrome
Other inherited mutations linked to elevated breast cancer risk include PALB2, ATM, and CHEK2.
Understanding Your Risk
Inheriting a mutation does not guarantee breast cancer, but it does increase your likelihood compared with the general population. Different mutations carry different levels of risk, making genetic counseling important for understanding your personal risk and potential preventive steps.
Additional Risk Factors
Beyond genetics, several factors can influence breast cancer risk:
Older age
Race or ethnicity: White women have higher overall risk, while Black women are more likely to develop aggressive types
Personal history of breast cancer
Dense breast tissue
Certain benign breast conditions, like atypical hyperplasia or LCIS
Reproductive factors, including early menstruation, late menopause, not having children or having children after 30, and not breastfeeding
Hormonal birth control or menopausal hormone therapy
Previous chest radiation
Overweight or obesity
Low physical activity
Excessive alcohol consumption
Screening Recommendations for High-Risk Individuals
The American Cancer Society recommends that those at high risk begin annual breast MRI and mammogram screening at age 30. High-risk individuals include those who:
Have a confirmed BRCA mutation
Have a close relative with a confirmed BRCA mutation
Have an inherited syndrome increasing breast cancer risk (e.g., Cowden or Li-Fraumeni syndromes)
Had chest radiation between ages 10 and 30
Have a lifetime risk of 20–25% or higher based on family history
High-risk individuals should continue annual screening as long as they remain in good health.
Key Takeaways
Cancer arises from DNA mutations, most of which occur spontaneously.
Some cancers are hereditary, caused by mutations passed down from parents, with BRCA mutations being the most common hereditary factor in breast cancer.
People at higher risk should discuss screening options, including yearly MRI and mammograms, with their healthcare provider to make informed decisions about monitoring and prevention.