Breast Cancer Family History Guidelines

Key Elements of a Strong Family History

A significantly strong family history of breast cancer includes having multiple affected first-degree relatives, especially those diagnosed before age 50, having relatives with bilateral breast cancer, male breast cancer, or ovarian cancer, or belonging to high-risk ethnic groups such as Ashkenazi Jewish descent 1, 2
Risk increases with the number of affected relatives in the family and closeness of the relationship 3
Family history of ovarian cancer at any age increases breast cancer risk 1, 2
Male breast cancer in the family significantly increases risk and suggests possible BRCA mutations 1, 4
Multiple primary cancers in the same individual, such as bilateral breast cancer, increase risk 1, 2

The National Comprehensive Cancer Network (NCCN) considers individuals from families with known BRCA1/BRCA2 or other breast cancer susceptibility gene mutations as having a significantly strong family history warranting genetic evaluation 1, 5
Personal history of breast cancer diagnosed at age 45 or younger is considered high-risk 1, 5
Personal history of breast cancer diagnosed at age 50 or younger with one or more close blood relatives with breast cancer at any age is considered high-risk 1, 5
Personal history of breast cancer at any age with two or more close blood relatives with breast and/or ovarian cancer at any age is considered high-risk 1, 5
Personal history of two breast primaries when the first breast cancer diagnosis occurred before age 50 is considered high-risk 1, 5
Personal history of ovarian/fallopian tube/primary peritoneal cancer is considered high-risk 1, 5
Close male blood relative with breast cancer is considered high-risk 1, 5

Ashkenazi Jewish heritage increases the risk of carrying BRCA1/2 mutations 6, 7
Other founder populations with increased risk include Icelandic, Swedish, Hungarian, and Dutch 1
For these populations, requirements for genetic testing may be lessened, such as breast or ovarian cancer at any age 2

Limited family structure may lead to underestimation of familial risk 1
Family history should be evaluated on both maternal and paternal sides independently 8, 3

Women with strong family history should be referred for genetic counseling and possible testing 9, 4
Women with a significantly strong family history may benefit from enhanced screening protocols, including earlier initiation of mammography and consideration of MRI screening 7
Family history assessment should be updated periodically as new cancer diagnoses in the family may change risk status 4

Focusing only on maternal side and ignoring paternal family history is a common pitfall 8, 3
Not accounting for small family size or limited information about family members is a common pitfall 1
Failing to consider ethnic background that may influence genetic risk is a common pitfall 6, 7
Not reassessing family history periodically as new cancer diagnoses occur is a common pitfall 4

If a first-degree relative was diagnosed with breast cancer before age 50, the risk increases more significantly than if she was diagnosed at older ages, according to the National Comprehensive Cancer Network 10
Male breast cancer in the family is a criterion for genetic counseling, as stated by the American Cancer Society 11
Family history of both breast and ovarian cancer is a criterion for genetic counseling, as stated by the American Cancer Society 11
Ashkenazi Jewish heritage with any affected relative is a criterion for genetic counseling, as stated by the American Cancer Society 11

MRI screening is not recommended for women with only one first-degree relative unless lifetime risk exceeds 20% based on formal risk models, as stated by the American Cancer Society 12

The Tyrer-Cuzick model is preferred when family history is the primary risk factor, as it accounts for age at onset and second-degree relatives, according to the Journal of Clinical Oncology 13
The Gail model underestimates risk in women with strong family histories and should not be used when family history is the primary concern, as stated by the American Cancer Society 11

Both maternal and paternal family history matter equally, according to the National Comprehensive Cancer Network 10