Common conditions

LYNCH Syndrome

What is Lynch syndrome?

Bowel cancer is a common cancer in UK, the risk of developing Bowel cancer increases as you age, certain lifestyle factors and conditions such as Crohn’s disease can also increase the risk.

Endometrial cancer is the most commonly diagnosed cancer in women, most endometrial cancers occur in women after the menopause and the average age of diagnosis of 60 years.  Being overweight is considered to increase a women’s risk of developing endometrial cancer.

A small amount of these cancers are due to an inherited condition known as Lynch Syndrome. A person with Lynch syndrome has a higher risk of developing certain cancers over their lifetime than a person in the general population. Lynch syndrome used to be known as hereditary non polyposis colon cancer (HNPCC), as one of the main risks is colorectal cancer.

As your cancer is one of the cancers associated with Lynch Syndrome, you are being offered a test that will check for gene faults in the 5 Lynch genes to help you and your doctor learn if you may have Lynch syndrome.

 What are the risks of cancer for a person who has Lynch Syndrome?

Typically there is about a 40 -80% lifetime risk of developing colorectal cancer, and in addition for females there is a 40-60% risk of endometrial ( womb) cancer and about a 10% risk of ovarian cancer. Other cancers which may be associated with Lynch syndrome include stomach • small bowel • bile duct/gall bladder • brain • pancreas • urothelial (kidney, ureter and possibly bladder) and skin cancer.

Some people with Lynch syndrome may have more than one primary cancer. It is helpful to your doctor to know if your cancer is due to Lynch syndrome in arranging your treatment and follow-up care.

 How is Lynch syndrome inherited?

Lynch syndrome is inherited following a pattern known as autosomal dominant inheritance. If you have an alteration in a Lynch syndrome gene then each child, male or female, has a 50% chance of inheriting the Lynch gene with the alteration.

The Lynch genes have an important job in the body

The Lynch genes help repair DNA mistakes that can happen in certain cells in the body. If you inherit a Lynch gene that is not working, this means that as you go through life, DNA mistakes might not get fixed and this can cause cells to grow out of control and become cancer cells.

Does everyone who inherits a Lynch variant develop cancer?

No. Not everyone who carries a Lynch syndrome variant will go on to develop cancer. If you have a gene variant, your family members can opt for genetic testing to see if they also have inherited the same gene variant.   As the risk of developing bowel cancer, and endometrial and ovarian cancer (if female), are higher than for a person who is not a Lynch syndrome carrier, certain screening procedures and follow up are recommended.

Follow up- Bowel:

This can involve colonoscopies. Bowel cancer is thought to develop from small nodules in the lining of the bowel wall, called polyps. There are different types of polyps and some do not change to become malignant. A type of polyp called an adenoma may sometimes progress to cancer. In the general population this change is thought to take place over a number of years. The change from an adenoma to cancer can happen more quickly in Lynch syndrome. Colonoscopy is currently recommended every two years for everyone with Lynch syndrome and their close relatives. The age at which to start varies depending on which Lynch syndrome gene is involved. A flexible telescope is passed along the colon via the anus so the entire rectum and colon can be examined. This is usually an outpatient procedure which may include light sedation. Bowel preparation is prescribed before colonoscopy to ensure that the views of the bowel wall are clear.

Screening of the bowel is still important after surgery for colorectal cancer because of the risk of developing further cancer. People with Lynch syndrome who need an operation to remove part of the colon may decide to have more of the colon removed to reduce the chance of developing additional polyps in the remaining bowel. This can be discussed with your surgeon.

Prevention of other cancers

Endometrial and ovarian cancer: The effectiveness of screening for other cancers associated with Lynch syndrome has not yet been proven, such as for endometrial and ovarian cancer. It is important to be aware of some symptoms that can occur. Endometrial cancer symptoms can include abnormal vaginal bleeding between periods or after the menopause, heavier periods than usual or vaginal discharge.  Symptoms of ovarian cancer may include a swollen abdomen, feeling full or loss of appetite, pelvic or abdominal pain, or needing to pass urine more frequently.

 Endometrial and ovarian cancer    risk-reducing surgery: Risk reducing surgery to remove the uterus, ovaries and fallopian tubes (total hysterectomy and bilateral salpingo-oophorectomy) may be considered by some women after they have completed their family. The best age to consider surgery is over 35 years. You can be referred to a gynaecologist to discuss this option. Hormone replacement therapy is usually recommended after risk-reducing bilateral salpingo-oophorectomy to offset negative impact of premature menopause, up until the time at which natural menopause would be expected to occur.

Exception Female PMS2 carriers: The risk of ovarian cancer from variants in PMS2 is not thought to be increased and the risk of endometrial cancer is only somewhat increased. Therefore for female carriers of a PMS2 gene variant removal of the ovaries is not suggested and hysterectomy (to remove the womb) can be considered from 45 years of age.

Gastric cancer:  In some Lynch families we notice more cases of gastric cancer. It is helpful to let your genetic counsellor know if you have any relatives who have developed this type of cancer. Routine screening for gastric cancer is not recommended. A one-off test can be carried out by your GP to detect a common stomach infection called Helicobacter pylori. The test can either be a breath test or a stool antigen test. If Helicobacter pylori is present antibiotics can be prescribed by your doctor. If you have upper gastrointestinal symptoms which can include heartburn and indigestion that does not go away, loss of appetite or difficulty in swallowing these should be investigated promptly.

Breast cancer: At present it is uncertain whether the breast cancer risk is increased in Lynch syndrome. Female Lynch carriers are advised to have breast screening as per the National Breast Cancer Screening Programme, Breast Check, from age 50 years, unless there is a family history of breast cancer.

Prostate cancer: Some research studies have found that male Lynch syndrome gene carriers have an increased risk of developing prostate cancer.   There is no national surveillance programme at present, male Lynch syndrome carriers can discuss prostate checks such as the use of PSA blood test with their GP, and symptom awareness. Prostate cancer symptoms can include frequent urge to urinate, blood in urine or semen, pain or burning urination.

What genes will I be tested for?

Testing will be offered for variants (alterations) in a number of genes that are known to give risk to Lynch syndrome. These genes are MLH1, MSH2, MSH6, PMS2 and the EPCAM gene.