What Is Hereditary Nonpolyposis Colorectal Cancer (HNPCC)?

Hereditary nonpolyposis colorectal cancer (HNPCC) is an inherited condition that increases your risk of colorectal cancer. It’s the most common cause of inherited colorectal cancer.

Genetic mutations that run in families cause HNPCC. People with these mutations often develop cancer before the age of 50.

Along with colorectal cancer, people with HNPCC are at an increased risk of many other types of cancer, such as:

• endometrial cancer
• stomach cancer
• ovarian cancer
• pancreatic cancer
• bladder cancer

Read on to learn more about HNPCC, including who’s at risk, how it’s diagnosed, and how you can improve your outlook.

Is hereditary nonpolyposis colorectal cancer (HNPCC) the same as Lynch syndrome?

HNPCC is also called Lynch syndrome. It’s responsible for about 3,800 colorectal cancers in the United States each year.

Experts estimate HNPCC causes 2% to 3% of colorectal cancers and occurs in an estimated 1 in 279 people.

Who’s at risk for hereditary nonpolyposis colorectal cancer (HNPCC)?

Genes inherited through your family cause HNPCC. Mutations in the following genes have been linked to HNPCC:

• MLH1
• MSH2
• MSH6
• PMS2
• EPCAM

If one of your parents has an associated gene mutation, you have a 50% chance of developing HNPCC. Likewise, if you have an associated gene mutation, your children each have a 50% chance of developing it.

Research suggests people of European ancestry have higher rates of HNPCC than people of other ancestries.

Inherited versus sporadic colorectal cancer

Colorectal cancer can be inherited or sporadic.

Sporadic cancers develop without inherited gene mutations associated with that cancer.

Inherited cancers can occur due to a genetic mutation passed through families or a cancer syndrome, like HNPCC, that causes clusters of cancer within a family.

Inherited cancer syndromes cause only about 5% to 10% of colorectal cancers. HNPCC is the most common syndrome that causes colorectal cancer.

People with HNPCC have up to an 80% lifetime chance of developing colorectal cancer. Females also have up to a 60% risk of endometrial cancer .

Is my child at risk for HNPCC?

Your biological child is at risk of developing HNPCC if you or the child’s other biological parent carry a gene mutation for HNPCC. If either parent has an associated mutation, your child has a 50% chance of developing it.

What are the symptoms of hereditary nonpolyposis colorectal cancer (HNPCC)?

HNPCC itself doesn’t cause symptoms, but it puts you at risk of developing colorectal cancer and many other cancers. People with HNPCC tend to develop colorectal cancer at a younger age than other people.

Symptoms of colorectal cancer can include:

• blood in your stools
• diarrhea
• constipation
• thin stools
• bloating
• abdominal pain
• unexplained weight loss
• fatigue
• vomiting

What other cancers are associated with HNPCC?

Colorectal cancer is the most common cancer associated with HNPCC and endometrial cancer is the second most common. Other associated cancers include:

• stomach cancer
• ovarian cancer
• pancreatic cancer
• ureter and kidney cancer
• bladder cancer
• small intestine cancer
• prostate cancer
• biliary tract cancer
• brain cancer, usually glioblastoma
• some skin cancers

How do doctors diagnose hereditary nonpolyposis colorectal cancer (HNPCC)?

General diagnostic tests for colorectal cancer include:

• a review of your personal and family medical history
• a physical exam
• stool test to check for blood
• blood tests, such as:
  • complete blood count (CBC)
  • liver enzyme test
  • tumor marker tests
• colonoscopy or proctoscopy
• biopsy

If a doctor thinks you might have HNPCC, they’ll test your blood for an associated gene.

A doctor may recommend genetic testing if any of the following are true:

• you develop endometrial cancer before age 50
• HNPCC is known to run in your family
• your risk of Lynch syndrome is estimated to be greater than 5%
• you have a family history of other cancer clusters

How is hereditary nonpolyposis colorectal cancer (HNPCC) treated?

HNPCC doesn’t have a cure, so treatment revolves around trying to catch cancer early and removing polyps before they grow.

If you have HNPCC, a doctor will likely perform regular screening tests, such as:

• colonoscopy
• ultrasound of your uterus
• uterus biopsy
• ovarian ultrasound
• blood tests
• endoscopy to look at your stomach and small intestines
• urine tests to look for urinary tract cancers
• MRI to monitor pancreatic cancer
• neurological exam to screen for brain cancer
• skin exam to monitor for skin cancer

Some research suggests taking aspirin daily may lower the risk of cancer for people with Lynch syndrome.

Sometimes, a doctor may recommend surgery before cancer occurs. You might receive:

• a hysterectomy to remove your uterus
• an oophorectomy to remove your ovaries
• a colectomy to remove all or much of your colon

What’s the outlook for people with hereditary nonpolyposis colorectal cancer (HNPCC)?

People with HNPCC and colon cancer have a better outlook than people with sporadic colorectal cancer. The 5-year survival rate is about 60% compared to between 40% to 50% in people with sporadic cases.

In a review of studies , researchers reported an even higher survival rate. They reported the overall survival of people with Lynch syndrome after diagnosis with colorectal cancer was about:

• 90% at 5 years
• 80% at 10 years
• 70% at 15 years.

Is there any way to prevent hereditary nonpolyposis colorectal cancer (HNPCC)?

You can’t prevent HNPCC because it’s caused by genes inherited from your parents, but you can improve your chances of catching cancer early by following a doctor’s recommended screening schedule.

Screening might include:

Cancer type	Frequency
Colorectal cancer	Colonoscopy every 1 to 2 years, typically from age 20 to 25
Endometrial cancer	Ultrasound and biopsy from age 30 to 35
Ovarian cancer	Ultrasound from age 30 to 35

In addition to screening, for endometrial and ovarian cancer, surgery may need to be considered as a more definitive way to prevent these cancers.

Takeaway

Hereditary nonpolyposis colorectal cancer (HNPCC) is a cancer syndrome that increases your risk of developing colorectal cancer and many other types of cancer, such as endometrial cancer.

People with HNPCC have a very high lifetime risk of developing cancer, especially at a young age.

If you have a family history of HNPCC, a doctor will want to screen you regularly for cancer. Catching cancer early gives you the best chance of having a good outlook.