17195 Lynch Syndrome And Hnpcc

Overview

Lynch syndrome is an inherited condition that raises your chances of developing certain cancers, especially bowel cancer (colorectal cancer) and cancer of the womb lining (endometrial cancer). It used to be called HNPCC, which stands for hereditary non-polyposis colorectal cancer. The name changed because we now know the condition increases risk for other cancers too. People with Lynch syndrome have a change in one of the genes that normally repairs DNA. This doesn't mean you will definitely get cancer, but your risk is higher than average.

No, Lynch syndrome is uncommon. Around 1 in 300 people may have it, but many are not aware because they haven't been tested.

Lynch syndrome affects men and women of all ethnic backgrounds. It is present from birth. People with a parent or sibling who carries the gene change are at higher risk of having it themselves.

Symptoms

Common symptoms

• Most people with Lynch syndrome have no symptoms until a cancer develops.
• If bowel cancer develops, symptoms can include blood in the stool, a lasting change in bowel habits, cramps, and unexplained weight loss.
• If womb cancer develops, symptoms may include abnormal vaginal bleeding, especially after menopause.

Symptoms in children

• Children rarely have symptoms of Lynch syndrome. The gene change is present, but cancers linked to Lynch syndrome usually appear in adulthood. Testing in children is not normally recommended unless there are specific medical concerns.

Symptoms in older adults

• Older adults may notice similar symptoms as anyone else, but they might also have other health conditions with overlapping symptoms. New symptoms like blood in the stool or unexpected bleeding should always be checked by a doctor.

Causes

Main causes

• A change (mutation) in one of the DNA repair genes: MLH1, MSH2, MSH6, PMS2, or EPCAM. These genes normally fix errors in DNA inside cells. When they don't work properly, errors can build up and cause cancer over time.
• This gene change is usually inherited from a parent who also has Lynch syndrome. In rare cases, it can happen with no family history.

Risk factors

• Having a parent, sibling, or child with Lynch syndrome or a known Lynch gene mutation
• A family history of bowel or womb cancer at a young age (under 50)
• A family history of several relatives with Lynch-related cancers across generations

When to see a doctor

See a doctor urgently if:

• If you notice blood in your stool, or a significant change in bowel habits lasting more than a few weeks
• If you have abnormal vaginal bleeding, especially after menopause
• If you have unexplained and persistent weight loss or severe tiredness

Book a routine appointment if:

• If you have any family history of bowel or womb cancer, ask your GP whether genetic testing or extra screening might be right for you
• If you already know you have Lynch syndrome, keep up with your scheduled screenings and appointments

Diagnosis

A doctor will look at your personal and family history to see if Lynch syndrome is possible. If it is, you may be referred to a genetics service for a blood test. The test checks for changes in the Lynch syndrome genes. Sometimes, an existing tumour or polyp is tested first to look for signs of DNA repair problems, which helps guide whether genetic testing is needed.

Tests that may be done

• A genetic blood test (called a multigene panel) that looks for Lynch syndrome gene changes
• A tumour test, such as immunohistochemistry (IHC) or microsatellite instability (MSI), on a sample of removed polyp or cancer tissue
• A predictive genetic test for family members once a gene change is found in a relative

What to expect at your appointment

Genetic testing starts with a discussion with a genetic counsellor. You'll talk about what the test means and what the results could mean for you and your family. If you decide to go ahead, it's a simple blood draw. Results may take a few weeks. A specialist will explain your results, your cancer risk, and the screening plan that's best for you.

Treatment

Treatment for Lynch syndrome is mostly about prevention: regular screening to find polyps or early cancers when they are easiest to treat. If cancer does develop, it is treated the same way as any other cancer. The plan depends on the cancer type, its stage, and your overall health. Your care team will explain all your options.

Self-care at home

• Keep all screening appointments — they are your best protection
• Learn to recognise body changes and report anything unusual to your doctor
• Avoid smoking and drink little alcohol
• Maintain a healthy weight and stay physically active

Medical treatments

If you develop a Lynch-related cancer, treatments may include surgery, chemotherapy, radiotherapy, immunotherapy, or other targeted therapies. These are used to remove or destroy cancer cells. The exact combination is personalised, and your doctors will discuss the evidence and possible side effects with you before starting any treatment.

When is surgery considered?

In some situations, people choose to have preventative (prophylactic) surgery to remove the organ most at risk, such as the colon (colectomy) or the womb (hysterectomy). This is a major decision, only considered for high-risk individuals, and should be made together with your specialist and genetic counsellor.

Living with this condition

Living with Lynch syndrome means incorporating regular checks into your routine and being mindful of your body. Most people continue to live full, active lives. Screening is the main job — it's relatively simple and can save your life.

Lifestyle tips

• Keep up with your screening plan, even if you feel well
• Stay active — aim for at least 150 minutes of moderate exercise each week
• Avoid smoking and limit alcohol
• Eat plenty of fibre: fruits, vegetables, and whole grains

Diet and exercise

There's no special diet that can erase Lynch syndrome, but healthy eating and regular exercise can help lower your overall cancer risk and improve your general health. Some research suggests a diet high in fibre and low in red and processed meat may be helpful.

Mental health and emotional wellbeing

Learning you have Lynch syndrome can bring anxiety, worry, and sometimes guilt. These feelings are normal. Talk to your doctor about counselling options. Remember, genetic knowledge is not a verdict — it is a guide. Knowing your risk empowers you to take action.

Prevention

You cannot change the genes you inherited, but you can greatly reduce your chance of cancer developing. Regular colonoscopy can find and remove polyps before they turn into cancer. For women, regular womb biopsies can detect early changes. A healthy lifestyle also helps.

Vaccines

There is no vaccine to prevent Lynch syndrome itself. However, keeping up with all recommended vaccinations — such as the HPV vaccine, which prevents other cancers — is still important for your overall health.

Screening programmes

Screening for Lynch syndrome usually includes a colonoscopy every 1 to 2 years, starting in your 20s or 30s or earlier if your family history suggests it. Women may be offered yearly womb sampling (endometrial biopsy), sometimes with ultrasound, to check the uterus. The exact schedule is tailored to the specific gene change and family history.

Complications

If left untreated

• Without screening, a cancer that could have been found early might grow and spread, making treatment harder
• The risk of developing more than one cancer over a lifetime is higher, especially in the bowel, womb, stomach, and urinary tract

Long-term outlook

With regular screening and early detection, the outlook for people with Lynch syndrome is very good. Most bowel and womb cancers found early are curable. Many people with Lynch syndrome live long and healthy lives. The most important thing is to stay on top of your follow-up plan and keep talking with your healthcare team.

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