Prevention
Your family history is a biomarker — record it properly
6 min read
Family history is free, requires no laboratory, and is one of the strongest predictors available for several major conditions. It is also the item most often recorded as a single vague sentence in a chart.
The detail is what carries the information. A grandmother diagnosed with breast cancer at 78 barely shifts your risk. A sister diagnosed at 38 changes your screening age, your eligibility for genetic testing, and possibly your management.
What to collect for each relative
Work outwards from first-degree relatives — parents, siblings, children — then second-degree: grandparents, aunts, uncles, half-siblings, nieces and nephews.
- The exact condition, not the organ it spread to
- Age at diagnosis, which matters more than age at death
- Which side of the family, since maternal and paternal lines are assessed separately
- Ethnic background, relevant for Ashkenazi Jewish BRCA founder mutations among others
- Any known genetic test results in the family, including negative ones
The patterns that trigger a different plan
Certain configurations move you out of population screening and into a higher-intensity pathway or a genetics referral.
- Breast cancer under 50 in a first-degree relative, or male breast cancer at any age
- Breast and ovarian cancer in the same family line
- Three or more relatives with colorectal, endometrial or related cancers across generations — a Lynch syndrome pattern
- Any first-degree relative with colorectal cancer, which typically moves screening to age 40 or ten years before their diagnosis
- Premature coronary disease: a male first-degree relative under 55 or female under 65
How risk models use it
First-degree relatives carry roughly twice the weight of second-degree relatives, because they share about 50% of your genome versus 25%. Models such as Gail, Tyrer-Cuzick, PREMM5 and BOADICEA formalise this, and some require the full pedigree to run at all.
QRISK3 includes premature coronary disease in a first-degree relative directly. The ASCVD Pooled Cohort Equations do not — which is one reason they can underestimate risk in families with early heart disease.
Keep it current
Family history is not a one-off form. Revisit it every few years, and after any new diagnosis in the family. A single new event can move you across a screening threshold.
Key takeaways
- Record the specific condition, the age at diagnosis and which side of the family.
- First-degree relatives carry roughly double the weight of second-degree relatives.
- Specific patterns trigger earlier screening or a genetics referral rather than a risk-score tweak.
- Update it after any new diagnosis in the family.
Related reading
Sources
- US Preventive Services Task Force, BRCA-Related Cancer: Risk Assessment, Genetic Counseling and Genetic Testing
- Hippisley-Cox J et al. Development and validation of QRISK3, BMJ 2017
- National Comprehensive Cancer Network, Genetic/Familial High-Risk Assessment guidelines
This article is educational and is not medical advice. Always discuss your own results with a qualified healthcare professional.
Know your risk, take action
Create a free account and get your first risk assessment in under ten minutes. No card required.