A Family Member Was Just Diagnosed with Cancer. Am I at Risk?

If you are reading this, someone you care about may have recently been diagnosed with cancer. You are probably feeling a mix of concern for them and uncertainty about what their diagnosis might mean for your own health. Both of those feelings are entirely reasonable, and asking the question “am I at risk?” is not selfish — it is responsible.

This article is designed to help you think clearly about what a family member’s cancer diagnosis may or may not mean for you, and to outline the concrete steps you can take to find out.

Most Cancer Is Not Inherited — but Some Is

The first thing to understand is that the vast majority of cancer — roughly 90 to 95 percent of all cases — is sporadic, meaning it develops from DNA changes that accumulate over a person’s lifetime due to aging, environmental factors, and random cellular errors. Sporadic cancers are not passed from parent to child.

The remaining 5 to 10 percent of cancers are hereditary, meaning they are driven by an inherited gene variant that was present from birth and can be passed to the next generation. When cancer runs in a family due to a hereditary variant, the risk of developing certain cancers can be significantly elevated — and knowing about that variant can open the door to prevention strategies that would not otherwise be available.

A single cancer diagnosis in your family does not automatically mean you carry a hereditary variant. But certain patterns are worth paying attention to. Learn more about the difference between hereditary and sporadic cancer.

Patterns That Suggest a Hereditary Component

Oncologists and genetic counselors look for specific patterns when evaluating whether cancer in a family may have a hereditary basis. The more of these that apply to your family, the more strongly a hereditary evaluation is warranted:

• Young age at diagnosis. Cancer diagnosed before age 50 — particularly breast, colorectal, or endometrial cancer — is more likely to have a hereditary component.
• Multiple affected relatives on the same side. Two or more close relatives on the same side (maternal or paternal) diagnosed with the same or related cancers is a meaningful signal.
• Cancer across generations. A grandparent, parent, and sibling affected by cancer — especially similar types — suggests an inherited pattern.
• More than one cancer in the same person. An individual diagnosed with two or more separate primary cancers may carry a gene variant that increases susceptibility broadly.
• Rare or characteristic cancers. Certain diagnoses are strong signals on their own: ovarian cancer at any age, male breast cancer, pancreatic cancer in the context of breast or ovarian cancer, or triple-negative breast cancer before age 60.
• Ancestry with known founder mutations. Individuals of Ashkenazi Jewish, Icelandic, Norwegian, Dutch, or French Canadian descent have higher prevalence of certain hereditary cancer gene variants.

If any of these patterns are present in your family, a structured risk assessment can help determine whether formal genetic testing is appropriate. Learn about who should consider genetic testing.

What You Can Do Right Now

You do not need to wait for a referral or a doctor’s appointment to begin evaluating your risk. There are practical steps you can take today:

Gather your family history. Document both sides of your family going back to grandparents if possible: who was diagnosed with cancer, what type, and at what age. Include aunts, uncles, and cousins. Even incomplete information is helpful — genetic counselors are trained to work with imperfect family histories.

Take a clinical risk assessment. Validated risk assessment tools can evaluate your personal and family history against established clinical guidelines from organizations like the National Comprehensive Cancer Network (NCCN). LifeShield’s assessment takes approximately five minutes and uses the same criteria that genetic counselors and oncologists apply in clinical settings.

Talk to your diagnosed family member. If it feels appropriate, ask whether their oncologist has discussed genetic testing. If your relative undergoes germline testing and a hereditary variant is identified, that information changes the picture for the entire family.

Do not substitute a consumer DNA test for clinical evaluation. If you have a real family history of cancer, a consumer genetic test is not an adequate substitute for clinical-grade testing. Learn about the differences between clinical and consumer testing.

If Your Mother or Sister Was Diagnosed with Breast Cancer

Breast cancer is the most common cancer in women, and most cases are sporadic. However, if your mother, sister, or daughter was diagnosed — particularly before age 50, or if she had triple-negative breast cancer — the hereditary breast and ovarian cancer syndrome associated with BRCA1 and BRCA2 gene variants should be evaluated. Learn more about BRCA1 and BRCA2 genes.

If a Parent Was Diagnosed with Colorectal Cancer

Colorectal cancer diagnosed before age 50 is a hallmark of Lynch syndrome, a hereditary condition caused by variants in DNA mismatch repair genes. Lynch syndrome also increases risk for endometrial, ovarian, stomach, urinary tract, and other cancers. Learn more in our Lynch syndrome guide.

If a Family Member Has Ovarian or Pancreatic Cancer

Ovarian cancer at any age is considered a strong indicator for hereditary cancer evaluation. Current NCCN guidelines recommend that all women diagnosed with ovarian, fallopian tube, or primary peritoneal cancer be offered germline genetic testing, regardless of family history. Similarly, pancreatic cancer — particularly when combined with a family history of breast or ovarian cancer — may indicate the presence of a BRCA2 or other hereditary variant.

You Do Not Have to Navigate This Alone

Learning that someone you love has cancer is already difficult. The added uncertainty about your own risk can feel overwhelming. But you do not need to navigate this alone. Genetic counselors are healthcare professionals specifically trained to help individuals and families understand hereditary cancer risk. Whether you choose to pursue testing or not, a counselor can help you understand where you stand. Read more about facing the fear of genetic testing.