Cancer is a group of diseases caused by mutations in various genes. Identifying these mutations and understanding their effects on disease development are crucial for assessing an individual's cancer risk. Having a mutation linked to cancer does not necessarily mean you will develop the disease. Likewise, having close relatives with cancer does not guarantee that you will get it. Understanding how these genetic changes influence cancer risk can help inform screening and treatment strategies. This article will explore the genetics of cancer, including how inherited and acquired mutations affect cancer risk.
How Can Genes Cause Cancer?
Cells naturally divide a limited number of times before dying, a process tightly regulated by various genes. Cancer can arise when mutations in these genes disrupt normal control, causing uncontrolled cell growth and division1. However, the exact link between specific mutations and cancer is not always clear2.
Mutations can be inherited (present from birth) or acquired over a person’s lifetime. When inherited mutations give rise to cancer, the condition is known as hereditary cancer. Acquired mutations, on the other hand, can result from environmental factors such as exposure to carcinogens like cigarette smoke3.
Some well-known cancer-associated mutations include those in the BRCA1 and BRCA2 genes, which significantly raise the risk of breast and ovarian cancer, as well as mutations in TP53, which are linked to multiple cancer types4,5.
Another key gene, HER2, plays a role in cell growth. In certain cancers, cells either overproduce HER2 or develop mutations that make it overly active, leading to rapid and uncontrolled tumor growth6,7.
Can We Inherit These Mutations?
We inherit genetic information from our biological parents, meaning we have physical traits similar to theirs, such as eye or hair color. However, this also means we can inherit mutations that increase our risk of disease8.
Inherited Cancer Gene Faults
Hereditary cancer syndromes are genetic disorders that increase an individual's risk of developing cancer due to inherited mutations. These syndromes result from mutations in specific genes, though the number and type of affected genes vary from case to case9.
Well-known hereditary cancer syndromes include Lynch Syndrome, which raises the risk of colorectal cancer, and Li-Fraumeni Syndrome, which is associated with various types of cancer. However, despite the existence of these syndromes, inherited mutations are estimated to cause only 5-10 percent of all cancers3,10.
What Cancer is Hereditary?
Many types of cancer are hereditary including cancers such as:
- Breast4
- Ovarian11
- Colorectal12
- Prostate13
- Pancreatic14
- Melanoma15
- Kidney16
- Retinoblastoma17
- Stomach18
Which Type of Cancer is Hereditary?
Not all genetic risk factors have the same likelihood of leading to cancer in an individual. This variation is explained by a concept called penetrance, which refers to the probability that a genetic mutation will result in cancer19. Mutations with high penetrance are more likely to cause cancer than those with low penetrance. For instance, BRCA mutations have an estimated penetrance of 29 percent, meaning that 29 percent of individuals carrying these mutations will develop cancer at some point in their lifetime20.
If My Parent Had Cancer, Will I Get It?
If one of your biological parents had cancer, it does not necessarily mean that you will develop cancer. As we’ve mentioned, different mutations carry different risks (penetrance). While mutations can increase your risk, it’s important to remember that genetics is just one part of the puzzle and that lifestyle choices and environmental factors also play a role21.
How Common Are Cancers Caused by Inherited Gene Changes?
Only about 5-10 percent of cancers are caused by inherited genetic mutations. The majority of cancers result from other factors, including exposure to carcinogens (cancer-causing substances) over time. These include tobacco smoke, which raises the risk of several cancers, and sun exposure, which increases the risk of skin cancer due to the DNA-damaging effects of UV radiation22,23.
Familial Cancer vs. Hereditary Cancer
Familial cancer and hereditary cancer may seem similar, but they are distinct. Hereditary cancer occurs when a specific, identifiable genetic mutation increases the risk of cancer within a family. In contrast, familial cancer refers to a higher-than-expected occurrence of cancer in a family without a clearly defined genetic cause24. In these cases, the increased risk may be due to genetic factors, shared environmental exposures (such as having many smokers in a family), or a combination of both.
Genetic Testing for Cancer Risk
If you believe you may be at a higher risk of developing cancer, you should consider genetic testing or counseling. Talk to your healthcare provider about your concerns to determine whether testing is appropriate for you.
Can I Reduce My Genetic Cancer Risk?
Although you cannot change your genetics, you can take steps to reduce the likelihood of cancer developing, even if you have a genetic predisposition. Regular screenings can help detect cancer early when it is more treatable. In some cases, preventive measures like prophylactic surgeries, such as mastectomy for individuals with BRCA gene mutations, can significantly lower the risk of cancer emerging25. Additionally, making healthier lifestyle choices, such as reducing tobacco and alcohol consumption, can further decrease the likelihood of cancer developing26.
A Family History of Cancer – What It Means for You
It’s important to understand the different ways cancer emerges in families and how this can impact your risk of developing a disease27. Factors that indicate you may have a cancer-associated genetic mutation include having:
- A first-degree relative (parents, siblings, children) with cancer
- Many occurrences of cancers in your family that could be caused by a genetic mutation (e.g., breast cancer and BRCA mutations)
- Close relatives with cancers linked to hereditary syndromes (e.g., colorectal cancer and Lynch syndrome).
Regular screenings are important for individuals with a higher risk of getting cancer. More screening means greater chances of finding cancer at an early stage. This means increased chances of better outcomes and more treatment options28.
Does Skipping a Generation Lower My Risk?
Cancers develop due to a complex interaction between genetics and environmental factors. Having a genetic mutation does not necessarily mean that a person will develop cancer. While genetic mutations can be inherited, they do not always lead to cancer, which means the disease may appear to skip a generation. However, our understanding of this complexity is still limited, and it is unclear whether cancer skipping a generation affects an individual's relative risk.
What If I Have a Known Gene Change?
Firstly, having a genetic mutation that increases your cancer risk does not mean you will definitely develop cancer. It is important to discuss your options with a healthcare provider or genetic counselor. Proactive steps may include creating a personalized screening plan to detect cancer early, as well as considering preventive measures. These can include lifestyle changes, risk-reducing medications like tamoxifen for certain types of breast cancer, or prophylactic surgeries such as mastectomy for individuals with BRCA gene mutations25,29.
Gene Changes and Other Factors
Cancer is a complex group of diseases that can develop for various reasons, some of which remain unknown. Factors such as genetics, environmental exposures, and lifestyle all contribute to cancer risk. Epigenetics may also play a role. These changes affect how genes are expressed without altering the genetic sequence itself30. While you cannot change your genetic makeup, you can influence certain factors that impact your cancer risk, such as lifestyle choices like smoking, diet, exercise, and regular screenings21.
Summary: Is Cancer Genetic? Debunking Myths & Explaining Real Risks
While genetics can play a role in cancer risk, most cancers are not directly inherited. Inherited genetic mutations account for only a small percentage of cases, meaning that having a family history of cancer does not necessarily mean you will develop the disease. Genetic testing is available for those at high risk, helping individuals make informed decisions about screenings and preventive measures.
However, genetics is just one piece of the puzzle. Lifestyle choices, such as maintaining a healthy diet, avoiding tobacco, and getting regular screenings, can significantly lower your overall cancer risk or reduce its severity. Understanding both genetic and environmental factors empowers individuals to take proactive steps toward cancer prevention and early detection. If you are concerned about your risk, consult with a healthcare provider to explore the best strategies for your personal health.
Regular screening can help catch cancers early. Consider booking an Ezra full-body MRI scan to catch any issues early when they are more treatable.
