Lynch Syndrome (also know as Hereditary non-polyposis colorectal cancer (HNPCC))
Lynch Syndrome is a condition that can run in families. People with Lynch syndrome have an increased risk of developing cancer of the large bowel (colorectal cancer), cancer of the womb (endometrial cancer) and some other cancers.
We hope this information answers your questions. If you have any further questions, you can ask your doctor or nurse at the hospital where you are having your treatment.
Lynch Syndrome (LS) is a rare condition that runs in families. Conditions that run in families are known as familial or hereditary.
LS is also known as hereditary non-polyposis colorectal cancer (HNPCC). Because people with HNPCC have an increased risk of some other cancers, and not just colorectal cancer, health professionals now tend to call the condition Lynch syndrome, named after the doctor who discovered it.
Lynch syndrome is the most common cause of hereditary bowel cancer. However, fewer than 5 in 100 (5%) of all bowel cancers are linked to LS. People with LS also have an increased risk of developing other cancers, the most common of which is womb (endometrial) cancer.
Other cancers that can occur in people with LS include: ovarian, stomach, pancreas, pancreas, small bowel, ureter and renal pelvis cancers.
Knowing about risk and having regular screening may help prevent some cancers and detect others in the early stages when they're curable.
How Lynch syndrome is inherited
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Our genes carry the information that is passed on (inherited) from our parents. Genes determine things like the colour of our eyes and affect the way our bodies grow, work and look.
LS is caused by an alteration in one of the genes known as the 'mismatch repair' gene. Mismatch repair genes normally work to help prevent you from getting cancer.
LS may be suspected in families with close blood relatives who have developed bowel, womb and ovarian cancer over several generations. They may have inherited an altered copy of one of the mismatch repair genes.
Three of the mismatch repair genes (known as MLH1, MSH2, and MSH6) are responsible for most cases of Lynch syndrome. Another mismatch repair gene called PMS2 is also sometimes tested for in cases of Lynch syndrome. If a person inherits an altered copy of one of these genes, it increases their risk of developing bowel cancer and some other types of cancer.
We have two copies of every gene – one from each of our parents. If someone has LS, it means they have a healthy gene but also one that's altered.
If that person has a child, there is a fifty–fifty chance that they will pass on the altered gene (only one copy of a gene is passed on from each parent).
LS is more likely if there are lots of cases of bowel and womb cancer on one side of the family that were diagnosed at an early age. However, not everyone with LS has a family history of cancer. This is because some people may be the first in their family to get it.
LS may be suspected if:
at least two relatives on the same side of the family have had bowel cancer
a family member developed bowel cancer at a young age (under 50)
there are cases of bowel and womb cancer on the same side of the family
three or more relatives on the same side of the family have had one LS-type cancer (not necessarily the same kind of cancer).
If you're worried about cancer in your family, speak to your doctor who can refer you to a family cancer clinic.
Signs and symptoms of Lynch syndrome
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LS itself doesn't cause any symptoms. It's an inherited syndrome that means a person has a higher risk of developing bowel and womb cancer.
Sometimes the first sign that a person has LS is when the symptoms of bowel or womb cancer develop. This generally happens at a younger age than for people whose cancers aren't due to an inherited faulty gene. With LS there's usually a history of these cancers in the family.
Symptoms of bowel cancer
Bowel cancer that doesn't run in families usually develops in people over 50, but with LS, bowel cancer usually occurs between the ages of 40 and 50 or younger.
Being aware of your normal bowel habit is important, particularly if you have or think you may have LS.
If you have any of the following symptoms it's important to get them checked out by a doctor:
blood on or in the stools (bowel motion)
diarrhoea or constipation for no obvious reason (ie a change in the normal bowel habit that lasts longer than six weeks)
unexplained weight loss
pain in the tummy or back passage
a feeling of not having emptied the bowel properly after a bowel motion.
Symptoms of womb cancer
It's also important to be aware of the symptoms of womb cancer if you have or think you may have LS. Any of the following symptoms should be checked out by a doctor:
abnormal vaginal bleeding (between periods, heavier periods or bleeding after the menopause)
pain in the lower abdomen (tummy), back or legs
pain or discomfort during sexual intercourse.
All these symptoms can be caused by conditions other than cancer, but it's always important to get them checked out by your doctor.
How Lynch syndrome is diagnosed
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It is sometimes possible to find out if someone has LS by doing a genetic test . If a person has a suspected LS-type cancer, a test may be done on a tissue sample taken from the cancer of a relative who has had cancer recently, or in the last few years. (Hospitals usually keep tumour samples for several years and can often supply tissue for this kind of testing).
If this genetic test is positive, the relative who has had cancer is asked for permission to take a blood sample so that a gene alteration can be looked for. It used to take a long time to find an alteration in a gene. But with new technology it now takes around 12 weeks or less.
If the altered LS gene is found, closely related family members (not affected by cancer) can, if they wish, be tested to see if they have inherited it.
Genetic testing can only be carried out if a person is willing to have it. It’s important to be aware that not everyone in a family will have the same feelings about genetic testing. And these differences can sometimes cause upset in families.
Before genetic testing, a person will have counselling to help them understand the possible results and what these results may mean for them and their family.
Sometimes the faulty gene can't be found in the person with the HNPCC-type cancer (because it's not HNPCC or there's a fault in the gene that research hasn't yet identified). If no gene change is found other family members can't be tested. However, based on their family history, they can still have regular bowel tests and womb checks (in women) to reduce their cancer risk.
What the test results mean:
If you've already had an LS-type cancer and have the altered gene, women may then be screened for womb or ovarian cancer. Both men and women may need regular screening of their bowels. The kind of screening you have will depend on the type of surgery (if any) you have already had.
If you have LS in your family and have inherited the altered gene, you'll be advised to have regular screening to reduce your risk of LS-type cancers. If you have children they will have a fifty-fifty risk of inheriting the altered gene. Your close relatives who have not had cancer may also have inherited the altered gene.
If you have LS in your family and have not inherited the altered gene, your cancer risk is the same as anyone else's. You won't need screening and your children will not be at increased risk of LS-type cancers.
Screening to reduce your risk
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Knowing your risk of cancer means you can have regular tests (screening). Bowel cancers and womb cancers can be curable when they're picked up early.
If a person is found to have inherited the altered gene, they'll usually be advised to have regular bowel screening from a young age. This would usually begin at the age of 25. Women may be referred in their thirties to a gynaecologist to discuss how to manage their risk of womb cancer.
If the altered gene isn’t found in the person with LS-type cancer, it's important that you still have screening as you may still be at risk of cancer. The same applies if you decide against genetic testing or can’t have it because a family member with LS-type cancer doesn’t want a test.
A colonoscopy is used to examine the bowel and diagnose any cancers early on when they're curable.
The test is usually carried out in the hospital outpatient department and takes about an hour. Your bowel has to be completely empty for the test. This means you'll have to follow a special diet for a few days beforehand. On the day before your colonoscopy, you'll be asked to take medicine (a laxative) to empty your bowel. Your hospital will give you instructions about preparing for a colonoscopy. Just before the test, you will be given a drug to make you feel more relaxed (a sedative). This may be given as an injection into a vein (intravenously).
Once you're lying comfortably on your side, the doctor or nurse will gently pass a flexible tube (a colonoscope) into your back passage. A colonoscope is a long, thin, flexible tube that has a tiny light and a camera on the end of it. It can easily pass around curves so most of the large bowel can be examined. During the test, photographs and samples of tissue (biopsies) may be taken. Any polyps (small growths) can also be removed before they develop into a cancer.
Afterwards, you will need somebody to go home with you and stay with you for 24 hours until the effects of the sedative wear off. It's important not to drive during this time. Colonoscopies are usually repeated every two years.
We don't yet know if womb screening in women with LS is helpful. Some women may be offered it, but it's not available everywhere.
The womb can be screened using a procedure called a hysteroscopy or by using a vaginal ultrasound. Your doctor or nurse will explain which test you will have. During a hysteroscopy a thin, flexible tube with a light at the end will be used to look inside the uterus. A vaginal ultrasound scan involves putting a small device that makes sound waves into the vagina. The sound waves are then converted into a picture by a computer.
We don't know if ovarian screening helps pick up ovarian cancer at an earlier stage. Occasionally some women may be offered it or they may have it done as part of a research trial.
The risk of developing ovarian cancer if you have LS is much lower than your risk of bowel or womb cancer. Screening can involve a blood test, a vaginal ultrasound or both. The blood test checks the levels of a protein called CA125.
It has been suggested that a regular dose of aspirin may help to prevent bowel cancer in people who have the LS gene alteration. However, we don’t yet know what the most helpful dose is, and aspirin can have harmful side effects. More research is needed into the possible benefits of aspirin for people with LS. If you have the altered gene and you want to know more about aspirin, your doctor can advise you.
If you develop bowel cancer, it's likely to be picked up early through having regular colonoscopies. Any LS-type cancer is treated in the standard way for that type of cancer.
Treatment for bowel cancer will usually involve surgery to remove the cancer. Further treatment with chemotherapy may be needed, depending on the stage of the cancer.
Treatment for womb cancer will usually involve removing the womb (hysterectomy) and the ovaries. Radiotherapy may also be given.
Occasionally with LS, it's recommended that the whole of the large bowel is removed as a preventative measure. This is known as risk-reducing surgery. It's usually only recommended where the risk of developing cancer is thought to be very high, or if a person with LS develops more than one bowel cancer.
Some women (when they've completed their families) may choose to have their womb and ovaries removed to reduce their risk of womb and ovarian cancer.
Knowing that you have Lynch syndrome or are at risk of it can be very difficult to cope with. The uncertainty of not knowing if you will develop cancer isn't easy to deal with, but it's important to remember that bowel cancer can be found early and cured. You may have concerns about genetic testing, screening or whether you should have risk-reducing surgery.
It's important to talk these concerns over with the doctors and nurses caring for you. They'll be happy to answer any questions you have.
You may have many different emotions, including anxiety and fear. These are all normal reactions and are part of the process that many people go through in trying to come to terms with their condition.
Many people find it helpful to talk things over with their doctor or nurse. Close friends and family members can also offer support.
This section has been compiled using information from a number of reliable sources, including:
DJ Ahnen et al. Clinical features of Lynch Syndrome (Hereditary non-polyposis colorectal cancer). UpToDate website http://www.uptodate.com (accessed October 2012).
PA Bonis et al. Lynch Syndrome (Hereditary non-polyposis colorectal cancer): screening and management of patients. UpToDate website http://www.uptodate.com (accessed October 2012).
Dynamed Summary. Hereditary non-polypoisis colorectal cancer (accessed October 2012).
Tobias J, and Hochhauser D. Cancer and its management. 6th Edition. 2010. Wiley-Blackwell.
Thank you to Ms Lorraine Cowley, and all of the people affected by cancer who reviewed this edition. Reviewing information is just one of the ways you could help when you join our Cancer voices network.