Environment
Family history and genetic risk — mapping your inheritance
Applies to: Breast, Ovarian, Colorectal, Pancreatic, Prostate
Your family history is one of the most powerful prevention tools you have, and most people have never mapped it. Doing so can change when and how you screen.
Full guide
The bottom line
Your family history is one of the most powerful and underused pieces of cancer-prevention information you have. A pattern of certain cancers in your family can mean you need to start screening earlier, screen more often, or consider genetic testing. Most people have never actually mapped it out. Doing so takes an afternoon and can change your entire screening plan.
What to actually collect
Build a simple family cancer tree covering first-degree relatives (parents, siblings, children) and second-degree (grandparents, aunts, uncles, nieces, nephews), on both sides. For each cancer, note: who had it, what type, and roughly what age they were diagnosed. Age matters enormously — cancer before 50 is a bigger red flag than the same cancer at 80.
The patterns that signal higher risk
- Multiple relatives with the same or related cancers (breast + ovarian, or colon + endometrial, cluster together in known syndromes).
- Cancer diagnosed young (before 50).
- A single relative with two different cancers.
- Rare cancers (male breast cancer, ovarian, pancreatic) — these carry more weight.
- Ashkenazi Jewish ancestry with any of the above (higher BRCA carrier rate).
- A known genetic mutation already identified in the family.
What to do with it
Bring your family cancer tree to your doctor and ask directly: "Based on this history, do I need earlier or more frequent screening, and should I see a genetic counselor?" Certain patterns move your screening ages up by years. A first-degree relative with colon cancer can mean starting colonoscopies at 40 or earlier, not 45.
On genetic testing
If your history fits certain patterns, genetic counseling and testing (BRCA, Lynch syndrome, and broader panels) can tell you whether you carry a mutation that raises your risk, which changes screening, and sometimes opens preventive options. Genetic counseling before testing helps you choose the right test and understand results. (See the genetic testing access guide for coverage details.)
Resources
- CDC "Knowing Is Not Enough" family history tool: cdc.gov/genomics.
- Surgeon General’s "My Family Health Portrait": phgkb.cdc.gov/FHH/html/index.html — free tool to build and share your tree.
- FORCE (hereditary cancer support): facingourrisk.org.
- National Society of Genetic Counselors: nsgc.org — find a counselor.
