Table 1

Guidelines for referral and screening mammography with one, two, or three relatives affected with breast cancer at various ages

Family history of breast cancer	Expected breast cancer cases between 40–50 y^1-150	Lifetime risk^1-151(population risk is 1 in 11)	Risk group^1-152	Early mammography^1-153	Specialist genetics clinic^1-154
1 relative ^1-160
1 relative >40 y	Maximum 1 in 50	Maximum 1 in 8	Low	No	No
1 relative <40	1 in 30-1 in 50	1 in 12-1 in 6	Low/moderate	Yes	No^1-164
Female <30 or male affected at any age	maximum 1 in 25	maximum 1 in 6
2 relatives ^1-160
2 relatives 50– 60 y	1 in 40	1 in 8	Low	No	No
2 relatives average age 40–49	1 in 25	1:6-1 in 4	Moderate	Yes	No^1-164
2 relatives average age 30–39	1 in 14	1 in 4-1 in 3	High	Yes	Yes
3 relatives ^1-160
3 relatives average age 50–60	1 in 15	1 in 4	Moderate	Yes	Yes
3 relatives average age 40–50	1 in 11	1 in 3	High	Yes	Yes
Breast and other cancers	Usually more than 1 in 25		Usually more than 1 in 6		Moderate/high	Yes	Yes
1 or more relative with breast cancer ⩽50 y + ⩾1 relative with ovarian cancer at any age or one relative with both	Usually more than 1 in 25		Usually more than 1 in 6		Moderate/high	Yes	Yes
1 or more relative with breast cancer <40 y plus relative with childhood malignancy	—	—	May be high	Avoid mammograms pending genetics review	Yes

↵1-150 Population risk for breast cancer age 40 to 50 is 1 in 100 (1%).
↵1-151 Population lifetime risk (age 20–80) years is 1 in 11 (9%).
↵1-152 Risk category: low risk <2 × population lifetime risk: moderate = 2–3 × population lifetime risk: high >3 × lifetime population risk.
↵1-153 Early screening mammography should start not younger than 35 years of age in the moderate risk group; the risk of cancer and potential benefits of screening are most likely to be seen in the 40–50 year age group.
↵1-154 Specialist genetics clinic: to be assessed with a view to genetic mutation analysis and more formal risk estimation.
↵1-160 “Relative” includes first degree relative and their first degree relatives (first degree relatives = mother, father, brother, sister, child).
A relative with clearly bilateral breast cancer can be viewed as two relatives for simplicity. A male relative with breast cancer counts as a young female (<40).
↵1-164 Ethnic origin may make mutation searching easier, for example Ashkenazi Jewish ancestry might mean genetic testing would be more helpful even with a less striking family history.