Is Cancer Hereditary?

The many types of cancer have genetic factors, but that doesn’t make them hereditary. A better question might be: Is cancer genetic?

Is cancer hereditary?

When it comes to cancer perhaps the most common question is whether it’s hereditary.

The simplest answer is that it has a genetic component. Certain types of cancer may be more common within some families. Some cancers you are more likely to inherit through your family tree. But genetic doesn’t mean hereditary.

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In some families, you may see one or more or cases of cancer, which leads one to ask: is cancer hereditary? But there also are major modifiable risk factors, which research has found can increase the chance of developing cancer.

Those include smoking, which increases the risk of developing virtually all cancers, exposure to known human carcinogens, exposure to radiation, overexposure to UV and UVA light as triggers to skin cancers, obesity and poor diet, exposure to certain hormone treatments, and infections such as HIV.

Is cancer genetic?

“Studying the role that genetics plays in cancer is tricky,” Max D. Gray writes. “We know that environmental risk factors play the most important role in the development of cancer, but there is, in some cancers, a hereditary component. The reason for this is likely due to a small genetic predisposition but mainly because lifestyle factors tend to be similar among family members. For example, in a family in which smoking is common, there is a greater risk of suffering from lung cancer.”

But some people do inherit mutated genes that make their chance of developing a certain cancer higher than normal. Women who have a mutated BRCA1 gene have an 80 percent chance of getting cancer at some point in their lives. “Up to 1 in 20 (5 percent) cancers are caused by an inherited faulty gene,” according to Cancer Research UK.

Cancers that may be caused by an inherited mutated gene and seem to run in families include, breast, ovarian, bowel and womb cancer, retinoblastoma, Hodgkin’s lymphoma, non-Hodgkin’s lymphoma, melanoma, and prostate cancer.

Hereditary cancer syndromes

Cancer is so common that most families have had a member who has had some form. While most cancers develop from environmental factors, the American Cancer Society (ACS) does identify family cancer syndromes, so named based on the rate of occurrence within a family.

Certain factors make it more likely that cancers in a family are caused by a family cancer syndrome, including many cases of an uncommon or rare type of cancer, cancers occurring at younger ages than usual, more than one type of cancer in a single person, cancers in both of a pair of organs, more than one childhood set of cancer in siblings, and cancer occurring in a gender not usually affected, the ACS says.

Before you decide a certain cancer runs in your family, gather some information (including talking to a medical geneticist or oncologist) first that will help inform you.

Ask questions, such as who is affected and how you are related, what type of cancer is it (is it rare?), how old was the relative when they were diagnosed, did the person get more than one type of cancer, and did they smoke or have other known risk factors?

Certainly there are hereditary breast and ovarian cancer syndromes.

For many years, doctors noticed that in some families, many of the women developed breast and or ovarian cancer. Often the cancers were found at younger than usual ages, and some of the women had more than one cancer. Some had breast cancer in both breasts, and some got both breast and ovarian cancer.

The distinction between genetic and hereditary may be lost on women who develop breast cancer. Still, it’s a genetic predisposition toward the cancer in certain families from a mutated gene, with environmental factors playing a role. That doesn’t necessarily make the cancer hereditary, but it’s a fine line inherent in a family risk that can easily be blurred.

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