When someone says, “Cancer runs in my family,” it often sparks concern—and for good reason. It may indicate a genetic pattern of inherited cancer risk in certain situations. However, not all cancers in the family are purely genetic. Sometimes, it’s due to shared habits, like diet, smoking, or exposure to similar environmental toxins.
This article will discuss the role of genetics, which cancers are inherited, how cancer can run in families, who should get tested for genetics, and—above all—what you can do to protect your family.
The Science Behind Genetics and Cancer
The risk of cancer increases when DNA in the cells mutates, which may be due to environmental factors (like radiation, exposure to chemicals, and pollutants) or errors during cell division. These mutations can disrupt how cells grow and divide, possibly leading to cancer.
What causes mutation in the cells?
It may be either inherited or acquired during a lifetime; it includes
- Inherited (germline) mutations: A Mutation in the germline means either sperm or ovum contains mutations and then passes them into the child in every cell.
- Acquired (somatic) mutations: Acquired during the lifetime due to lifestyle and environmental changes and habits like aging, tobacco use, or sun exposure.
Note: Acquired mutations do not pass into the offspring; it’s only inherited mutations that raise your risk, but they don’t confirm that cancer will develop.
If cancer runs in the family, what does it indicate?
If the same or related type of cancer runs in your family, particularly at younger-than-normal ages, it may suggest a hereditary cancer syndrome, meaning a certain gene mutation might be passed from one generation to the next, raising the risk for certain cancers.
It should be clear that not all cancers that appear in families are genetic; they can be due to environmental exposure (such as pollution or harmful chemicals) or lifestyle habits such as smoking and drinking.
What is the prevalence of hereditary cancer?
Studies by the American Cancer Society and other leading health organizations suggest that
- About 5–10% of all cancers are considered inherited.
- The remaining 90% to 95% are the result of random mutations over a lifetime, which are frequently affected by age, environment, and behavior.
Inherited vs. Sporadic Cancer: What does it mean
Not all cancers are inherited. In fact,
- Sporadic cancer: most common, covers 90-95% of the cancer that occurs at random due to environmental or lifestyle factors.
- Hereditary cancer accounts for nearly 5–10% of all cancers and arises from mutations that run in families.
Knowing the difference can have a big impact on screening, prevention, and treatment.
What are the top genetic causes of cancer?
Errors during cell division can cause genetic mutations. Some of which, when inherited, lead to an increased risk of certain cancers.
Genetic mutations commonly linked to certain cancers include:
- BRCA1 and BRCA2 may increase the risk of breast, ovarian, prostate, and pancreatic cancers.
- TP53: Associated with rare genetic conditions such as Li-Fraumeni syndrome, which raises the risk for various cancers at a young age.
- MLH1, MSH2, MSH6, PMS2: Genes associated with Lynch syndrome, which increases the risk of colorectal, uterine, and other cancers.
- APC: increases colorectal cancer risk due to conditions like familial adenomatous polyposis.
- RET Gene Mutation: Multiple Endocrine Neoplasia type 2 (MEN2) raises the risk of thyroid and adrenal gland cancers.
- PTEN Gene Mutation: Related to Cowden syndrome, it increases the risk of breast, thyroid, and endometrial cancers.
- CDH1: Hereditary diffuse gastric cancer (HDGC). Also, it increases the risk of lobular breast cancer.
- STK11 (LKB1) can lead to Peutz-Jeghers syndrome, a rare condition associated with gastrointestinal and other cancers.
How to Know If Cancer Runs in Your Family?
Here are some of the key warning signs to check for the risk of hereditary cancer if:
- The same or a related type of cancer is found in multiple family members.
- Diagnosed at a very early age (breast cancer at the age of 40)
- One person has multiple cancers (such as colon or uterine)
- You belong to Ashkenazi Jewish ancestry (people with a high prevalence of BRCA mutation).
- Person have known hereditary syndromes (Lynch, FAP)
If these key warning signs apply, consult with your genetic counselor or oncologist to evaluate cancer risk.
How Cancer Is Diagnosed?
Genetic testing is usually done to check for the underlying genetic mutation linked to cancer; it’s usually done through blood or saliva. It’s usually considered if:
A family has a strong history of cancer. First-degree member or close relative tested positive for genetic mutation.
Steps to Take while genetic testing:
- Family medical history of at least 3 generations.
- Take note of the cancer type, age at diagnosis, and any connections.
- Discuss this with your doctor to decide whether testing is appropriate for you.
What are the common types of familial cancer?
- Breast Cancer: primarily affects women and has a strong link with BRCA1 or BRCA2 genes, which can increase the risk of breast cancer by up to 80%.
- Ovarian Cancer: It often goes undetected in the early stages due to vague or subtle symptoms. This cancer is strongly associated with both BRCA mutations and Lynch syndrome. Regular screening is a must.
- Colorectal Cancer: Can be hereditary, particularly in individuals with Lynch syndrome or Familial Adenomatous Polyposis (FAP). Early and regular colonoscopies are crucial, especially for precancerous polyps, before they turn into cancer.
- Prostate cancer: This disease frequently runs in families, especially if it is discovered before the age of 55. In men, genetic mutations like BRCA1, BRCA2, and others can greatly raise the risk.
- Pancreatic and stomach cancers: Although less common, they may be associated with BRCA mutations or Lynch syndrome. A person with a strong family history should consider genetic counseling.
How to stay safe if cancer runs in your family?
A genetic mutation or a family history of the disease does not guarantee cancer. You can lower your risk through certain steps:
Regular Checkup and Monitoring
Depending on your risk profile, doctors may recommend
- Start getting annual mammograms or breast MRIs at a younger age.
- Colonoscopies every 1-2 years rather than every ten years.
- Ultrasound TVS (Transvaginal) to check for ovarian cancer.
Healthy Lifestyle practices
While genes can’t be changed, behavior can. Key habits include
- Eating a healthy, plant-based diet.
- Maintain a good, healthy weight.
- Avoid tobacco and alcohol.
- Work out regularly.
- Stress management and getting enough sleep.
Preventive Surgery
Individuals with high risk (e.g., BRCA carriers) may be considered for preventive surgeries like mastectomy or ovary removal to reduce risk.
Prevalence of Hereditary Cancers: Global vs. India Comparison
Below is a table with estimated data for familial cancer prevalence in India and globally.
| Cancer Type | Global Hereditary/Familial Prevalence | Familial/Hereditary Prevalence in India (Estimated) | Key Genetic Syndromes/Genes |
| Breast Cancer | ~5–10% are hereditary (due to high-penetrance genes); ~15-20% familial | ~6–10% estimated to be hereditary | BRCA1, BRCA2, TP53 (Li-Fraumeni), PTEN (Cowden), PALB2, CHEK2, ATM |
| Ovarian Cancer | ~10–15% of cases have a hereditary cause | ~10–15% of cases are linked to BRCA or Lynch syndrome | BRCA1, BRCA2, Lynch Syndrome (MLH1, MSH2, MSH6, PMS2), RAD51C, RAD51D, BRIP1 |
| Colorectal Cancer | ~5–10% are familial, and ~3–5% are due to high-penetrance genes | ~5% have genetic basis; higher in younger age groups | Lynch Syndrome (MLH1, MSH2, MSH6, PMS2, EPCAM), FAP (APC), MUTYH-associated polyposis (MUTYH) |
| Prostate Cancer | ~5–10% of cases are due to inherited mutations; up to 15–20% are familial | Limited data; familial cases potentially rising | BRCA1, BRCA2, HOXB13, ATM, CHEK2, Lynch Syndrome genes |
| Pancreatic Cancer | ~5–10% have a familial/genetic component | ~4–6% estimated to be hereditary | BRCA2, PALB2, CDKN2A (FAMMM), ATM, Lynch Syndrome genes, PRSS1 |
| Stomach (Gastric) Cancer | ~1–3% of cases are linked to hereditary syndromes | ~1–3% estimated to be familial | CDH1 (Hereditary Diffuse Gastric Cancer), Lynch Syndrome, FAP, Peutz-Jeghers Syndrome |
| Endometrial Cancer | ~5% linked to Lynch Syndrome | Data limited; ~3–5% estimated hereditary cases | Lynch Syndrome (MSH2, MLH1, MSH6, PMS2, EPCAM) |
| Thyroid Cancer | ~3–5% cases are familial | ~3–5% familial cases, mostly medullary thyroid cancer | RET mutations (MEN2 syndrome for Medullary), DICER1 (Pleuropulmonary Blastoma Family Tumor Predisposition) |
| Melanoma | ~10% familial cases (often multifactorial) | Rare in India; familial cases are very low due to low incidence | CDKN2A, CDK4, BAP1 (BAP1 Tumor Predisposition Syndrome), XP (Xeroderma Pigmentosum) |
| Kidney (Renal) Cancer | ~3–5% of cases are due to inherited syndromes | <3% of cases estimated to be familial | VHL (von Hippel-Lindau), MET (Hereditary Papillary RCC), FH (Hereditary Leiomyomatosis & RCC), BAP1 |
| Brain Tumors | ~5% may be associated with genetic syndromes | Limited data; estimated ~2–5% | Li-Fraumeni Syndrome (TP53), NF1 (Neurofibromatosis type 1), NF2 (Neurofibromatosis type 2), TSC1/TSC2 (Tuberous Sclerosis Complex) |
Point to Note
- Cancers caused by inherited gene mutations that run in families are referred to as familial cancers.
- Limited data for India may be due to insufficient genetic testing and awareness.
- Familial cancers are primarily caused by syndromic conditions such as Lynch syndrome, BRCA mutations, and FAP.
- The numbers are based on current data and may change with new research and epidemiological findings.
Final Thoughts
While most cancers aren’t inherited, a family history of cancer can serve as an important warning sign. Understanding your genetic risk empowers you to take preventive action, whether through early screening, lifestyle adjustment, or, when needed, genetic testing.
Remember, cancer is not just about genes—it’s about genes and choices. If you’re concerned, talk to the best oncologist near you about the best personalized plan for you and your loved ones.
FAQs
If my parents had cancer, would I get it too?
Not necessarily. While family history may raise your risk, many people with a family history never develop cancer, and vice versa.
Can I get cancer even if it doesn’t run in my family?
Yes. Most cancers are sporadic (may occur during a lifetime) and can develop without any family history.
If I have a BRCA gene, will I get cancer?
No. A mutation increases your risk, but it doesn’t ensure that cancer will develop. If you have a family history, it requires genetic testing.
What has more impact on cancer risk—lifestyle or genetics?
Up to 50% of cancers are caused by bad lifestyle habits like smoking, poor diet, obesity, and lack of exercise, even if you have a genetic history of cancer. Healthy lifestyle choices can significantly lower your risk.
What age should I start screenings if I’m at higher risk?
Depending upon your family history, you may need to start in your 20s or 30s. Ask your oncologist for specific testing.
Is genetic testing covered by insurance?
Yeah, many cancer clinics and hospitals provide insurance if you fit the medical requirements. Check with your provider or ask your genetic counselor.
