Ultimate Guide to Inherited Cancer & Genomics

Updated September 30, 2019

This article was scientifically reviewed by YourDNA

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Genes, Mutations, and Cancer

While there’s still so much for scientists to learn about cancer, how it develops, and how it can be cured, decades of research show that in some cases, there can be a link between a person’s DNA and their chances of developing the disease.

In fact, some kinds of cancers are considered to be hereditary cancers that are prevalent in some families.

What's in this Guide?

Disclaimer: Before You Read

It is important to know that your genes are not your destiny. There are various environmental and genetic factors working together to shape you. No matter your genetic makeup, maintain ideal blood pressure and glucose levels, avoid harmful alcohol intake, exercise regularly, get regular sleep. And for goodness sake, don't smoke.

Genetics is a quickly changing topic.

The National Cancer Institute’s hereditary cancer definition explains that the disorder occurs when there is a “higher-than-normal risk of certain types of cancer,” and that hereditary cancers are caused by gene mutations that are passed from parent to child.

So, what genes are mutated to cause cancer? Researchers understand that there’s no one specific cancer gene that leads to any form of the disease.

Instead, specific kinds of mutations in certain genes can increase a person’s likelihood of developing the disease.

Is Cancer Genetically Inherited?

Many people worry that they may be at risk of developing a certain type of cancer based on their family’s health history.

For example, someone who has a mother and grandmother who had breast cancer may feel that they will likely develop the disease.

Many people wonder, “What percentage of cancer is genetic?” and “Is cancer hereditary from parents?” According to the National Cancer Institute, only about 5 to 10 percent of all cancers have a genetic component.

However, many people may be predisposed to developing the same cancer as a family member due to similar lifestyles, especially those linked to a higher risk of cancer development (such as being a family of smokers or tobacco users, or working in the same industry that may have regular exposure to carcinogens or toxins).

How can genes cause cancer?

Genes impact almost everything about our bodies — how they operate, grow, and what they look like.

That’s because the role of a gene is to provide instructions for how the body should make certain proteins that keep the body balanced and functioning.

But sometimes genes have mutations that impact these instructions, leading parts of the body to not function as they should, which can cause a variety of disorders and illnesses.

These mutations can lead to abnormalities and incorrect gene instructions that create abnormal proteins, make no proteins at all, or cause certain cells to multiply and form tumors, lumps, or other tissues known as cancer.

Differences Between Hereditary Cancer and Other Cancers

You should know that there are differences between hereditary cancers and other forms of the disease.

While only 5 to 10 percent of cancers are considered hereditary, researchers understand that there are about 50 specific gene mutations linked to certain kinds of cancers.

Generally, people wonder if the cancer they have is hereditary cancer vs. familial cancer. They may also ask “Is cancer genetic or environmental?” In reality, the disease is divided into three categories:

  • Sporadic cancer: This type of cancer occurs at random. People diagnosed with sporadic cancer often do not have a family health history of the disease.
  • Hereditary cancer: These types of cancer are linked to specific gene mutations that are inherited — passed from parent to child. Many people in one family may have the same type of cancer or a similar form of the disease, and it’s likely that people with this form often develop the disease earlier than other people who may have developed it sporadically.
  • Familial cancer: With familial cancer, multiple family members may have developed the same or a similar type of cancer, though there is no clear inheritance pattern. In these cases, researchers believe the risk of developing a certain type of cancer is due to a blend of genetics and environmental risk factors — such as all being smokers.

Risks of Inherited Cancers

Inherited cancers can feel like a dark cloud hanging over a family, and many people who believe they have a familial or hereditary risk of cancer worry that they’ll develop the disease at some point in their life.

You should know that being in a family with a hereditary predisposition to a certain form of the disease does not guarantee that you will have it.

While your chances of developing a particular form of cancer may be higher, it’s possible that you can go through life without ever having cancer at all. Still, people with inherited cancers:

  • Usually develop the same form as other family members
  • Are often diagnosed with cancer earlier than people who develop the same cancer sporadically
  • May increase their chances of getting cancer even more if their lifestyle also increases their risk factor (such as working with cancer-causing chemicals or smoking)
  • May pass along the same cancer-linked genetic mutation to their children

Thanks to a variety of tests offered by cancer genetic testing companies, it’s possible to learn if you have a heightened risk of developing a certain type of cancer.

With this information in hand, you can work on reducing your environmental and lifestyle risks, or making other medical decisions that help combat the potential development of cancer.

Hereditary Cancer Syndromes

You may have heard the term hereditary cancer syndromes. What is hereditary cancer syndromes?

It’s simply another name for types of cancer linked to genetically passed mutations that lead to specific forms of the disease.

Hereditary cancer syndromes increase a person’s chances of developing cancer within their lifetime. There are several types of hereditary cancer syndromes; some inherited cancer syndrome examples include:

  • Cowden Syndrome, which causes the body to have many noncancerous growths and a higher risk of developing breast, thyroid, and endometrial cancer
  • Breast and Ovarian Cancer Syndrome increases a person’s risk of developing breast and ovarian cancer, as well as prostate cancer in men
  • Multiple Endocrine Neoplasia is a syndrome that leads to tumors on the endocrine system, impacting the pituitary gland, parathyroid gland, and the pancreas
  • Familial Adenomatous Polyposis can lead to cancer of the large intestine and rectum and causes the body to grow an excessive number of noncancerous polyps in the colon
  • Lynch Syndrome is linked to an increased risk of a variety of cancers, including stomach, brain, skin, prostate, liver, small intestine, and colon, among others

According to the National Institutes of Health, there are nearly 30 hereditary cancer syndromes.

Many people wonder if there is a cancer genes list that lays out just which gene mutations lead to a heightened risk of the disease.

Some of the most common genes linked with hereditary cancers include:

Related Cancer
BRCA 1 and 2 . . . .Breast, ovarian, fallopian tube, pancreatic, prostate,

MLH1. . . .Pancreatic, uterine, colon

PMS2. . . .Breast, ovarian, fallopian tube, pancreatic, uterine,

CDH1. . . .Breast, gastric

STK11. . . .Breast, ovarian, fallopian, pancreatic, uterine, colon,

TP53. . . .Breast, pancreatic, colon

ATM. . . .Breast, pancreatic, prostate

Applying Genomics to Cancer

When it comes to determining if you may have an inherited cancer, you may be considering a test from one of many cancer genetic testing companies.

But it’s easy to get lost in the scientific lingo. You may have heard the term “cancer genetics” thrown around.

The easiest cancer genetics definition to understand is that the term refers to the study of how DNA plays a role in the development of cancer in some people.

Companies that specialize in cancer genetics often offer genetic testing and genomic testing. The difference between the two is important to know.

Genetics vs. Genomics

If you’re exploring genomic testing companies, you may be unsure how a genomic test differs from genetic testing. Here’s how the two differ:

  • Genetics: Genetics explores genes and how they are inherited, as well as how certain mutations and disorders are passed from parent to child. When using genetic tests, researchers are often looking at specific segments of DNA to understand if they are functioning properly.
  • Genomics: If genetics is hyperfocused on portions of your DNA, then genomics takes a larger picture into account. Genomics studies how many genes interact with one another, as well as with a person’s environment.

Why genomics research is critical to progress against cancer

Genomic research is extremely important when it comes to battling cancer, both with treatment and in research.

That’s because genomics takes into account a variety of factors — such as lifestyle and environment — that can combine with a person’s genetic risk level and increase or reduce their chance of developing the disease.

Genome sequencing in cancer diagnosis and treatment call help patients, doctors, and researchers have a better understanding of how cancer develops, and how it can be treated since it offers a more tailored approach.

Relating Inherited Risk Factors to Cancer Genomics

If you choose to undergo cancer genomics testing, one important factor your doctor will explore is your inherited genetic risk.

While genetic testing can show whether or not you have certain genetic mutations inherited from your parents, genomics can see just how those mutations are interacting with other genes.

In some cases, geneticists and doctors can determine if those mutations are severe enough to cause particular forms of cancer, and how they may respond to other mutations or cancer risk factors.

Even though you gain your DNA from your parents, there are still minute differences that make you unique — and those differences can increase or even decrease the chances that you’ll be diagnosed with cancer in the future.

No two people have the same level of risk, and genomic testing can give you a more personalized view of your inherited risk.

Testing for Hereditary Cancer Syndromes

For people who believe they have a “cancer cluster” or family health history of cancer, testing for hereditary cancer syndromes can provide more information used for lifestyle changes and medical decisions.

Many people worry that the hereditary cancer test cost is too much, though what you pay depends on several factors: what kind of test you have performed, what you are testing for, and if you have insurance coverage.

Many at-home DNA testing kits can use a saliva sample to test for certain genetic mutations that may be inherited, such as BRCA 1 and 2. Those tests can range from $100 to $300.

Having a hereditary cancer test done through your doctor’s office can be as little as $300, ranging up to the $1,000 or more mark.

What is genomic testing for cancer?

Cancer genomics testing can be a strong tool for people who may be at risk of hereditary cancer syndrome.

This testing looks for genetic abnormalities that may cause cancer or tumors, and with that information, helps your doctor develop a course of treatment specific to that gene mutation.

This testing has been especially beneficial for people diagnosed with cancer that is not responding to other forms of treatment since it is tailored to a specific type of mutation, instead of a generalized approach to cancer treatment.

Who should consider genomic testing?

Generally, genetic testing is recommended for people who may have an inherited risk of cancer, but who have not been diagnosed.

On the other hand, genomic testing can be exceptionally beneficial during cancer treatment, especially for:

  1. People diagnosed with cancer that is not responding to traditional treatments
  2. People who have a family health history of a specific kind of cancer, who have not been diagnosed, but may have noncancerous tumors and polyps

Getting Your Test Results for Hereditary Cancer Syndromes

Whether you choose to have a genetic test for cancer performed, or your doctor recommends a genomic test, you should know that results are often received back within a few weeks.

With genetic testing, your results will explain whether or not your DNA contains certain known mutations that are linked with cancer, including those that often appear in families.

What do the results mean?

So, what does it mean if results say that your DNA tested positive for having a cancer-linked mutation?

You should know that this doesn’t mean you have cancer, but that you have a higher risk of developing the disease compared to someone who doesn’t have that mutation and my be diagnosed sporadically.

In addition, having results that are negative for inherited cancer genes doesn’t mean you’ll never develop cancer.

Test results can give you insight into the need to work on reducing your lifestyle and environmental risk factors, but they’re not a guarantee that you will or won’t develop cancer.

Understanding hereditary cancer syndrome test results can be scary and confusing, so working with your doctor or a genetic counselor can help you best understand what your specific results mean, and what to focus on next.

Does Someone Who Inherits a Cancer Susceptibility Variant Always Get Cancer?

Despite decades of research, cancer scientists still don’t fully understand why some people get cancer and others don’t.

With that said, know that having a cancer susceptibility variant doesn’t mean you’ll definitely get cancer, even if many other people in your family have.

Other factors, such as lifestyle and environmental risks play a large role in cancer development, even for people who have inherited genetic mutations linked to cancer.

The Pros and Cons of Seeking Your Genetic Information

While genetic testing of any kind can be a great tool in helping you take control of your medical decisions and health, there are pros and cons to weigh.

For some people, knowing their risk for inherited cancers is stressful and emotionally taxing; for others, having this information provides freedom to live without fear.

Only you can decide if you should have this kind of testing performed. Some of the benefits of genetic testing for cancer to consider include:

  • Knowing about your risk can help you make lifestyle and environmental changes to help reduce your risk
  • Helping you educate yourself about cancer warning signs and symptoms so that you can be an informed watchdog for cancer development
  • You can use that information when planning for children and determining if you want to pass along a potential mutation
  • Helping family members who may be battling cancer to have a better idea if it is an inherited cancer, and thus having more treatment options
  • To provide insight into your own cancer treatment

But just as there are benefits, there are also downsides to genetic testing for cancer. Some of the cons include:

  • Anxiety, depression, and emotional upheaval related to finding out about an increased risk of cancer (which you may or may not develop)
  • Having a false impression that not having cancer-linked genetic mutations means you won’t ever have cancer
  • Feeling guilty when you do not have an increased cancer risk while other family members might

If you believe that you may benefit from genetic testing for cancer, speaking with your doctor to determine if you are a candidate is a great first step.

Options If You Have An Increased Risk of Cancer

Finding out that you have an increased risk of cancer due to inherited genes can be scary.

Many people who learn this about themselves wonder, “Can genetic cancer be prevented?”

Unfortunately, there’s no way for anyone to totally prevent cancer. But, there are some things you can do to help reduce the chances of developing the disease:

  • Stop smoking or using tobacco
  • Be sure to use sunscreen, hats, and skin protection while outdoors
  • Treat your body well by through a healthy diet and regular exercise
  • Be sure to have up-to-date vaccinations to protect against viral infections that can trigger cancer cell production
  • Speak with your doctor about your cancer risk, and plan for regular screenings at home and at the doctor’s office

While you can’t do anything about your genetic predisposition for cancer, you do have control over these lifestyle choices that can make a major difference.

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