From the Guidelines
Breast cancer risk factors include both non-modifiable and modifiable factors, with the most significant non-modifiable risk factors being genetic mutations, such as BRCA1 and BRCA2, and a family history of breast cancer, as noted in the 2024 study by the American College of Radiology 1. The non-modifiable risk factors for breast cancer include:
- Being female
- Increasing age (especially over 50)
- Family history of breast cancer
- Personal history of breast cancer
- Certain genetic mutations (particularly BRCA1 and BRCA2)
- Early menstruation (before age 12)
- Late menopause (after age 55)
- Dense breast tissue
- Previous chest radiation Modifiable risk factors include:
- Alcohol consumption
- Obesity (particularly after menopause)
- Hormone replacement therapy (especially combined estrogen and progesterone therapy)
- Physical inactivity
- Not having children or having first pregnancy after age 30 Women who breastfeed have a slightly lower risk of breast cancer, as suggested by the 2019 study by the European Society for Medical Oncology 1. Understanding these risk factors is crucial because some can be managed through lifestyle changes, such as limiting alcohol, maintaining a healthy weight, staying physically active, and carefully considering hormone therapy options, as recommended by the 2015 study by the National Comprehensive Cancer Network 1. Regular screening is especially important for those with multiple risk factors, though having risk factors doesn't guarantee developing breast cancer, and many women who develop breast cancer have no apparent risk factors beyond being female and aging, as noted in the 2018 study by the American College of Radiology 1.
From the FDA Drug Label
The following risk factors were used: age; number of first-degree female relatives with breast cancer; previous breast biopsies; presence or absence of atypical hyperplasia; nulliparity; age at first live birth; and age at menarche. The risk factors for breast cancer include:
- Age
- Number of first-degree female relatives with breast cancer
- Previous breast biopsies
- Presence or absence of atypical hyperplasia
- Nulliparity
- Age at first live birth
- Age at menarche 2
From the Research
Risk Factors for Breast Cancer
The risk factors for breast cancer can be divided into two main categories: inherent and extrinsic factors.
- Inherent factors include:
- Age: as women get older, their risk of breast cancer increases 3
- Sex: breast cancer is more common in women than men 3
- Race: some races are more prone to breast cancer than others 3
- Genetic makeup: having a family history of breast cancer or carrying certain genetic mutations, such as BRCA1 or BRCA2, increases the risk of breast cancer 4, 5, 6, 7
- Extrinsic factors include:
- Reproductive history: factors such as early menstruation, late menopause, and having children at an older age can increase the risk of breast cancer 4, 3
- Medical history: having a previous diagnosis of breast cancer or certain benign breast conditions can increase the risk of breast cancer 6, 3
- Lifestyle factors: factors such as diet, physical activity, and use of hormonal contraceptives or hormone replacement therapy may also play a role in breast cancer risk 3
- Family history of cancer: having a family history of breast or ovarian cancer can increase the risk of breast cancer 5, 7
Genetic Risk Factors
Genetic mutations, such as BRCA1 and BRCA2, can significantly increase the risk of breast cancer.
- Women with a BRCA1 or BRCA2 mutation are at higher risk of developing breast cancer, especially at a younger age 4, 5, 6, 7
- The risk of breast cancer in BRCA1 and BRCA2 mutation carriers is influenced by factors such as reproductive history and family history of cancer 6
- A prior diagnosis of breast cancer is a risk factor for breast cancer in BRCA1 and BRCA2 carriers 6
Breast Cancer Risk After Age 60
The risk of breast cancer remains high after age 60 in both BRCA1 and BRCA2 mutation carriers.