Hereditary Nonpolyposis Colorectal Cancer (HNPCC)
What is hereditary nonpolyposis colorectal cancer (HNPCC)?
Hereditary nonpolyposis colorectal cancer (HNPCC) is a type of colorectal cancer caused by genetic changes (mutations) that run in families.
Is Lynch syndrome the same as HNPCC?
HNPCC is sometimes called Lynch syndrome. HNPCC and Lynch syndrome are related but not exactly the same.
HPNCC refers to people and/or families who have Lynch syndrome-associated cancer that’s diagnosed before age 50. This can include colorectal cancer and cancers of your endometrium, small bowel, ureter and renal pelvis.
How does HNPCC affect me?
HNPCC typically occurs on the right side of your colon. This colorectal cancer type causes few (if any) growths (polyps) in your colon. Nonpolyposis means no polyps.
How common is HNPCC?
Between 2% and 4% of all colorectal cancers are HNPCC. Anyone can get HNPCC and most people receive a diagnosis before age 50.
Symptoms and Causes
What are the symptoms of HNPCC?
HNPCC may not cause any symptoms at first. As cancer grows, you may have:
- Abdominal pain or bloating.
- Appetite loss.
- Bloody stools.
- Unexplained weight loss.
What causes HNPCC?
When you inherit certain gene mutations from your biological parents, you have a family cancer syndrome. These syndromes are genetic disorders associated with colorectal cancers.
Lynch syndrome is the family cancer syndrome that causes HNPCC. Lynch syndrome develops when you have mutations in the MLH1, MSH2, MSH6, PMS2 and EPCAM genes.
These genes help correct the mistakes that happen during DNA replication. With these genes mutated, cells are unable to fix DNA replication errors, resulting in an increased tendency of normal cells to become cancer cells.
Is HNPCC contagious?
HNPCC isn’t contagious. But the HNPCC gene mutation runs in families. Families that have this mutation may have several members with colorectal cancer or other cancers linked to Lynch syndrome.
The mutated genes and the associated risk of developing HNPCC can pass from one generation to the next.
Diagnosis and Tests
How do healthcare providers diagnose colorectal cancer?
Healthcare providers typically diagnose colorectal cancer with a physical examination and colonoscopy. Tell your provider if you have a family history of HNPCC.
What tests do healthcare providers use to confirm HNPCC?
Your provider may recommend genetic testing to confirm that you have the genetic mutations associated with Lynch syndrome. Your provider will also:
- Ask you if anyone in your immediate family has or had colorectal cancer, especially if their diagnosis occurred before age 50.
- Rule out familial adenomatous polyposis (FAP), another inherited form of colorectal cancer caused by genetic mutations different from HNPCC.
Management and Treatment
Will I need surgery for HNPCC?
Healthcare providers typically treat HNPCC with surgery (colectomy). You may have:
- Partial colectomy or segmental colectomy (removal of part of your colon).
- Proctectomy (removal of your colon and rectum).
- Total colectomy (removal of your entire colon).
What other treatments do healthcare providers use for HNPCC?
If colorectal cancer has spread (metastasized), your healthcare provider may recommend other treatments in addition to surgery:
Healthcare providers usually prefer immunotherapy because it’s often more effective with fewer side effects.
How can I prevent HNPCC?
Inherited genetic mutations cause family cancer syndromes. There’s no way to prevent these gene mutations. If someone in your family has Lynch syndrome or HNPCC, talk to your healthcare provider about whether you should have genetic testing.
Screening and preventative surgery can help reduce risk of death in people with HNPCC.
How do I know if I’m at risk for HNPCC?
If genetic testing has confirmed you have gene mutations associated with Lynch syndrome, your healthcare provider may recommend screening for colorectal cancer beginning in your 20s. Detecting cancer early offers the best chance for successful treatment.
Outlook / Prognosis
What can I expect if I have HNPCC?
If you have HNPCC, you may be at higher risk for HNPCC-related cancers. Your healthcare provider may recommend getting checked regularly for certain cancers, including:
Is HNPCC curable?
Lynch syndrome isn’t curable. Total colectomy can treat HNPCC and prevent colon cancer.
What is the prognosis for people with HNPCC?
The five-year survival rate for people with HNPCC is about 60%. That means 60% of people diagnosed with HNPCC are alive five years after diagnosis.
The overall 10-year survival from colorectal cancer in Lynch syndrome is 70% to 88%.
How should I take care of myself if I have HNPCC?
Tell your healthcare provider right away if you have new symptoms of colorectal cancer. To help prevent colorectal cancer, you should:
- Avoid smoking.
- Eat healthy foods.
- Exercise regularly.
- Get all cancer screenings your provider recommends.
- Limit the amount of alcohol you drink.
- Maintain a healthy weight.
Frequently Asked Questions
Is my child at risk for HNPCC?
If you have Lynch syndrome, your child has a 50% chance of having the genetic mutations that cause this syndrome. If they inherit the mutations, they’ll have a higher chance of developing HNPCC.
Are FAP and HNPCC colon cancers the same?
HNPCC and FAP (familial adenomatous polyposis) are both genetic colon cancers, but they’re caused by mutations in different genes. People with FAP develop many growths (polyps) in their colon. HNPCC causes few or no polyps.
People with FAP develop thousands of polyps in their colon, while individuals with HNPCC (hereditary nonpolyposis colorectal cancer) develop only a few flat colon polyps. These polyps in both conditions tend to be precancerous that will transform into cancer over a short period of time
A note from Cleveland Clinic
Hereditary nonpolyposis colorectal cancer (HNPCC) is a type of colorectal cancer caused by genetic changes (mutations) that run in families. Healthcare providers treat HNPCC with surgery and systemic therapies like chemotherapy and immunotherapy (when needed).
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