When Cancer Risk Is in Your Genes

Cancer has many causes, and you can often lower your risk by eating better, getting more exercise and making other lifestyle changes. More than 80 percent of lung cancer cases, for example, are linked to smoking.

But your increased risk for certain cancers may be lurking in your genes. You might carry a particular genetic mutation that was inherited from your mother or father. Or you may have acquired it because of an error by your body’s complex system of making new cells.

Cancer is often the result of the combination of your unique set of genes and the life you have lived. Throughout your life, your body makes new cells to replace those that have died. Unfortunately, each time your body makes a new cell, there is a remote chance the copy will be defective – like a typo.

Your body also has systems in place to catch and destroy these mistakes. But some of these defective cells can evade these safeguards and become cancerous. Yet even then, there is no guarantee you will develop cancer.

Think of your cancer risk as a cup that you are filling up. Those inherited cancer-causing genetic mutations go into the cup. Other things also contribute, including smoking, being sedentary and not eating well. When the cup overflows, that’s when you get cancer.

Can You Inherit Cancer?

One of the more common myths about cancer and genetics is the belief that if one of your parents has a particular cancer or genetic mutation, that means you will get the disease. Even if you carry a genetic mutation linked to a particular cancer, it doesn’t mean you will get sick. But your risk is higher than normal.

Among the best-known mutations are the BRCA1 and BRCA2 genes, which can increase a woman’s risk for breast cancer. Consider that the average woman has a 13 percent chance of developing breast cancer at some point in her life. But with either the BRCA1 or BRCA2 variant, that risk increases to 70 percent by the age of 80.

So, if a parent had cancer, that doesn’t necessarily mean you are in danger. But it’s something you should explore with your doctor, as some cancers are more likely to be hereditary. Your risk is also likely to be greater if you have siblings or other family members who have gotten cancer before the age of 50.

Genetic Links

One in three people will be diagnosed with cancer during their lifetime, and it’s not uncommon for several members of the same family to have cancer. But it’s estimated that only about 5 percent to 10 percent of cancers have strong links to genes inherited from a parent. Researchers are learning more all the time, but among the best-known examples:

• BRCA1 and BRCA2: Mutations in these genes are linked to both breast and ovarian cancer. However, there are instances where these cancers run in families that don’t carry these defective genes, leading researchers to believe there may be other genes that have not yet been identified.
• Lynch syndrome: This genetic condition increases your risk for a wide range of cancers, including colorectal cancer, endometrial cancer and ovarian cancer.
• Li-Fraumeni syndrome: This rare genetic disorder increases risk for several cancers, including sarcoma, leukemia and brain cancer.
• PALB2: When functioning correctly, this gene can help your body prevent cancer. But a mutation can lead to higher risk for breast cancer and pancreatic cancer.

Value of Genetic Testing

If you have been diagnosed with cancer, you may want to consider genetic testing. It could change the way your cancer is treated, and it could offer additional guidance to family members, regarding their own risk.

Increasingly, doctors can tailor treatments to the genetic characteristics of tumors. For example, there is a class of drugs that takes advantage of weaknesses in the faulty BRCA1 and BRCA2 genes. Knowing that your breast cancer is related to the BRCA genes might also help you decide to have a bilateral mastectomy or have your ovaries and fallopian tubes removed as a precaution.

And if you have a mutation with a known cancer link, your children or siblings may choose to have their own testing done. This could lead to preventive surgeries or earlier screening for cancers. It could also provide peace of mind for those who don’t have the mutation.

And while it may be tempting to turn to one of the direct-to-consumer genetic tests, there are potential pitfalls. A better approach is to work with a genetic counselor, who can make sure you are testing for the right genes, help you understand your results and what to do next if you have the mutation.