Hereditary Cancer Common Questions

dna molecule structure

What are the risk factors for hereditary (familial) cancer?

Certain types of cancer can run in families, meaning that more than one person in a family is diagnosed with the same type of cancer. Several things might cause this. Family members share their genes as well as their behaviors — both of which can raise the risk for cancer.

Smoking, drinking alcohol, eating highly processed foods, having a sedentary lifestyle, spending a lot of time in the sun, and working in the same industry where there is toxic exposure are examples of behaviors that families often share and that can increase the risk of developing cancer. In general, you can change your own lifestyle behaviors to lower your cancer risk.

Even more important is to find out whether you carry an abnormal gene that is linked to higher cancer risk. Hereditary cancer risk is passed down through a family — from one generation to the next. While these are often called “inherited cancers,” you inherit the abnormal gene, not the cancer itself. That’s why, if two or more family members have the same cancer, if a family member is diagnosed with cancer at a very young age, or someone in your family has multiple types of cancer, it may be a good idea to get tested to find out your own genetic risk for cancer.

If you do have a mutation in a cancer gene, there are steps you can take to reduce your risk or to find cancer at an earlier, more treatable stage. You can get regular screenings to ensure it is caught in early stages, change any lifestyle behaviors that may contribute to it, and, in some cases, undergo preventive treatment.

It’s important to understand that not everyone who has a genetic risk factor will develop hereditary cancer. Remember, knowledge is power. Know all of your cancer risk factors — both the behavioral ones you can change and the genetic ones we can help you control, so you can make good decisions and protect your health.

What types of cancer are hereditary?

Some cancers are caused by mutations in certain genes that are passed along through families. These inherited cancers account for about 5-10% of all cancers. If one of your parents has a mutation, your chance of inheriting that mutation is 50%. That means some children inherit the elevated cancer risk while others do not.

The good news is that there are now very good genetic tests to detect mutations in up to 84 different genes that are linked to a higher-than-average risk for various types of cancer, including:

  • Breast cancer
  • Colon cancer
  • Prostate cancer
  • Ovarian cancer
  • Uterine cancer
  • Melanoma (a type of skin cancer)
  • Pancreatic cancer

Gene mutations can cause family patterns of cancers called syndromes. Some syndromes and the associated genes that cause them are:

  • Hereditary Breast Ovarian Cancer syndrome (BRCA1, BRCA2, and other genes)
  • Li-Fraumeni syndrome (TP53)
  • Cowden syndrome (PTEN)
  • Lynch syndrome (MLH1, MSH2, MSH6, PMS2, EPCAM)

Do hereditary cancers come from your parents?

The short answer is, they can. All cancers occur when something goes wrong in a gene that prevents it from functioning properly (a mutation) and causes it to divide abnormally. Everyone’s genes change with age and in response to things we are exposed to, like strong sunlight, cigarette smoke, alcohol, and chemicals or other pollutants.

These “acquired mutations” cause the great majority of cancers. Because acquired genetic changes accumulate over time, most cancers are diagnosed in older people. However, about 5-10% of cancers are caused by inherited genetic mutations that parents can pass on to their children. If a parent has one of these mutations, each child has a 50% chance of inheriting it.

Children who inherit the faulty gene have a higher-than-average risk of developing a particular cancer, but it is not guaranteed that all of them will develop cancer. Often, additional genetic changes are needed to trigger cancer development. Families that pass a genetic mutation from generation to generation usually have a pattern of specific types of cancer in a group of close relatives.

Whether you should consider genetic testing to find out if you are at risk for hereditary cancer depends on:

  • How close your family members with cancer are to each other and to you
  • What type(s) of cancer they have
  • How old they were when they were diagnosed

Generally speaking, the more relatives you have with similar cancers and the younger they were at diagnosis, the more likely it is that an inherited genetic mutation is responsible. If these criteria fit you, speak to your doctor about getting tested to find out if you are at high risk for hereditary cancer.

Can familial cancers skip a generation?

Yes, it is not guaranteed that someone will develop cancer just because they inherited a particular genetic mutation. There are many reasons why the impact of an inherited gene mutation can appear to skip a generation — such that a parent may have the mutation but never develop cancer, whereas one of their children who inherits the mutation from them will develop cancer.

First, some inherited mutations are more likely than others to trigger cancer development. Second, you may be able to take proactive measures to help prevent cancer from developing even if you have inherited a genetic vulnerability. For example, you can make lifestyle changes such as eating more vegetables, fruits, and grains, getting more exercise, quitting smoking, using sunscreen more often, and reducing or eliminating alcohol.

In the case of mutations that are associated with certain aggressive reproductive cancers, you may consider having preventive surgery such as a mastectomy (breast removal), hysterectomy (uterus removal), or oophorectomy (ovary removal). Finally, other factors in addition to a genetic mutation are also required for many inherited cancers to develop.

Researchers are at work every day to uncover all the factors that are needed to trigger cancer development. As we learn more about why it occurs in one person but not another who has similar genetic risks, we become better at preventing, diagnosing, and treating it for everyone.