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Definition
Lynch syndrome is a rare inherited condition that increases your risk of colon cancer and other cancers. Lynch syndrome is also known as hereditary nonpolyposis colorectal cancer (HNPCC). A number of inherited syndromes can increase your risk of colon cancer, but Lynch syndrome is the most common. An estimated 2 percent to 3 percent of colon cancers — or two or three out of every 100 colon cancers — are thought to be caused by Lynch syndrome.
Families that have Lynch syndrome usually have more cases of colon cancer than would typically be expected. Lynch syndrome also causes colon cancer to occur at an earlier age than it might in the general population.
Symptoms
People with Lynch syndrome may experience:
- Colon cancer that occurs at a younger age, especially before age 45
- A family history of colon cancer that occurs at a young age
- A family history of endometrial cancer
- A family history of other related cancers, including ovarian cancer, kidney cancer, stomach cancer, small bowel cancer, liver cancer or other cancers
Causes
Lynch syndrome runs in families in an autosomal dominant inheritance pattern. This means that if one parent carries a gene mutation for Lynch syndrome, there's a 50 percent chance that mutation will be passed on to each child.
The defective genes inherited in Lynch syndrome are responsible for correcting mistakes in DNA. DNA is the genetic material that contains instructions for every chemical process in the body. As your cells grow and divide, they make copies of their DNA and it's not uncommon for some minor mistakes to occur. Normal cells have mechanisms to recognize mistakes and repair them. But people who inherit one of the abnormal genes associated with Lynch syndrome lack the ability to repair these minor mistakes. An accumulation of these mistakes leads to increasing genetic damage within cells and eventually can lead to the cells becoming cancerous.
When to seek medical advice
If you have concerns about your family history of colon or endometrial cancer, bring it up with your doctor. Request an evaluation of your family history and your cancer risk.
If a family member has been diagnosed with Lynch syndrome, tell your doctor. Ask to be referred to a genetic counselor. Genetic counselors are trained in genetics and counseling. They can help you understand Lynch syndrome, what causes it and what type of care is recommended for people who have Lynch syndrome. A genetic counselor can also help you sort through all the information and help you understand whether genetic testing is appropriate for you.
Tests and diagnosis
If your doctor suspects you may have Lynch syndrome, he or she may ask you questions about your family history of colon cancer. This may lead to other tests and procedures to diagnose Lynch syndrome.
Family history
A family history of colon cancer, particularly when it occurs at a younger age, may alert your doctor to the possibility that you or members of your family may have Lynch syndrome. Researchers have devised guidelines, called the Amsterdam criteria, to determine who should be referred for further Lynch syndrome testing.
The Amsterdam criteria include:
- Three relatives with any HNPCC-associated tumor, including colorectal cancer. Other HNPCC-related tumors are those affecting the endometrium, ovaries, stomach, small bowel, kidney, brain, and skin, among others. At least two of these family members should be first-degree relatives, such as a parent, child or sibling.
- Two successive generations of affected family members.
- Diagnosis of one family member with this cancer before age 50.
While the Amsterdam criteria give doctors a general idea of which families may pass the genetic mutations associated with Lynch syndrome, the criteria aren't perfect. Many people meet the Amsterdam criteria, but aren't found to have Lynch syndrome. Conversely, many people with Lynch syndrome have families that don't meet the Amsterdam criteria.
If your family history meets the Amsterdam criteria, your doctor may recommend you undergo further testing.
Tumor testing
If you or someone in your family has been diagnosed with cancer, special testing may reveal whether the tumor has specific characteristics of Lynch syndrome cancers. Samples of cells from a colon cancer, a precancerous colon polyp or an endometrial cancer can be used for tumor testing. If you or someone in your family has been diagnosed with cancer in the last several years, the hospital where you received care may be able to supply a tissue sample. These tissue samples are often stored for 10 years or longer.
Tumor testing can reveal whether your cancer was caused by the genes related to Lynch syndrome. Tumor tests include:
- Immunohistochemistry (IHC) testing. IHC testing uses special dyes to stain tissue samples. The presence or absence of staining indicates whether certain proteins are present in the tissue. Missing proteins may tell doctors which mutated genes caused the cancer.
- Microsatellite instability (MSI) testing. Microsatellites are sequences of cellular DNA. In people with Lynch syndrome, there may be errors or "instability" in these sequences.
Positive IHC or MSI test results indicate that you have mutations in the genes that are connected to Lynch syndrome. But results can't tell you if you have Lynch syndrome or not because it's possible to spontaneously develop these gene mutations. About 15 percent of all colon cancers have a positive MSI result, but most aren't caused by Lynch syndrome.
Genetic testing
Genetic testing looks for changes in your genes that indicate that you have Lynch syndrome. You may be asked to give a sample of your blood for genetic testing. Using special laboratory analysis, doctors look at the specific genes that can have mutations that cause Lynch syndrome.
A positive genetic test result, meaning that gene mutations were discovered, doesn't mean that you're certain to get cancer. But it does mean your lifetime risk of developing colon cancer is thought to be about 60 percent to 80 percent. That means that for every 100 people with Lynch syndrome, between 60 and 80 people will develop colon cancer, while some 20 to 40 people won't develop colon cancer. Your risk of other cancers also is increased.
A negative result, meaning gene mutations weren't found, is more complicated. If other members of your family have been found to have Lynch syndrome, but you didn't have the genetic mutations, your risk of colon cancer is the same as the general population. If you're the first in your family to be tested for Lynch syndrome, a negative result may still indicate that you have a high risk of colon cancer — especially if you have a strong family history of colon cancer.
Your genetic counselor can discuss the benefits and risks of genetic testing with you. He or she will explain what genetic testing can tell you and what it can't.
Complications
Beyond complications for your health, a genetic disorder such as Lynch syndrome brings about many other areas of concern. Your genetic counselor is trained to help you navigate all the areas of your life that are affected by your diagnosis, such as:
- Your privacy. The results of your genetic test will be listed in your medical record, which may be accessed by insurance companies and employers. You may worry that being diagnosed with Lynch syndrome will make it difficult to change jobs or health insurance providers in the future. Most states have laws to prevent use of genetic information by insurance companies. Your genetic counselor or an attorney can discuss the laws in your state and what protections they offer.
- Your extended family. Undergoing genetic testing for Lynch syndrome has implications for your entire family. You may worry about the best way to tell family members that you're undergoing genetic testing. A genetic counselor can guide you through this process.
- Your children. If you have Lynch syndrome, your children have a risk of inheriting your genetic mutations. If one parent carries the genetic mutations for Lynch syndrome, each child has a 50 percent chance of inheriting those mutations.
Treatments and drugs
Colon cancer associated with Lynch syndrome is treated similarly to other types of colon cancer. However, surgery for Lynch syndrome colon cancer is more likely to involve the removal of more of the colon, since people with Lynch syndrome have a high risk of developing additional colon cancer in the future. Your treatment options will depend on the stage and location of your cancer, as well as your own health and personal preferences. Treatments for colon cancer may include surgery, chemotherapy and radiation therapy.
Cancer screening for people with Lynch syndrome
If you have Lynch syndrome, but haven't been diagnosed with an associated cancer, your doctor will develop a cancer-screening plan for you. Stick to your doctor's recommended plan. Screening for cancer can help your doctor find tumors at their earliest stages — when they're more likely to be cured.
As part of your cancer-screening plan, your doctor may recommend you undergo:
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Colon cancer screening. A colonoscopy exam allows your doctor to see your entire colon and look for areas of abnormal growth that may indicate cancer. During a colonoscopy, you receive a sedative to help you relax. Your doctor inserts a long, flexible tube into your rectum. A camera on the end of the tube transmits images to a video screen that your doctor uses to see the inside of your colon.
People with Lynch syndrome typically begin colonoscopy screening every other year starting in their 20s. Your doctor may recommend you undergo colonoscopy every year when you reach your 30s.
- Endometrial cancer screening. Women with Lynch syndrome may undergo annual endometrial biopsy to screen for cancer beginning in their 30s. During an endometrial biopsy, your doctor removes a small piece of tissue from your uterus. The tissue is examined to look for changes in the cells that may indicate cancer.
- Ovarian cancer screening. Your doctor may recommend an annual ultrasound examination of your ovaries if you have Lynch syndrome. By comparing annual ultrasound images, your doctor may be able to see changes to your ovaries that may indicate cancer. Talk to your doctor about when to begin ovarian cancer screening.
- Urinary system cancer screening. If your family has a history of urinary system cancers related to Lynch syndrome, such as kidney cancer, your doctor may recommend annual screening for these cancers. Analysis of a urine sample may reveal cancerous cells.
- Gastrointestinal cancer screening. If your family has a history of gastrointestinal cancers associated with Lynch syndrome, such as stomach cancer and small intestine cancers, your doctor may recommend screening for these cancers beginning in your 30s. An endoscopy procedure allows your doctor to see your stomach and other parts of your gastrointestinal system. During an endoscopy procedure, your doctor looks for unusual areas that may indicate cancer.
Your doctor may recommend other cancer-screening tests if your family has a history of other cancers. Ask your doctor about what screening tests are best for you.
Surgery to prevent cancers caused by Lynch syndrome
In certain situations, you and your doctor may opt for surgery to prevent cancer in the future. If your increased risk of cancer makes you nervous or fearful for your health, surgery to remove your colon may put your mind at ease. Or if you're unable to comply with the need for frequent cancer screenings, you may opt to have your colon removed. But all operations carry risks. Discuss the benefits and risks of preventive surgery with your doctor.
Surgical options for preventing cancer may include:
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Surgery to remove your colon (colectomy). Surgery to remove your entire colon will eliminate the chance that you'll develop colon cancer. Little evidence exists to show that removing your colon has any advantage over frequent cancer screening, in terms of helping you live longer. Yet, some people prefer the peace of mind.
Talk to your surgeon about your surgical options. One option in this situation involves removing your entire colon and attaching your small intestine to your rectum (ileorectal anastomosis). This allows you to expel waste normally.
- Surgery to remove your ovaries and uterus (oophorectomy and hysterectomy). Preventive surgery to remove your uterus eliminates the possibility that you'll develop endometrial cancer in the future. Removing your ovaries can reduce your risk of ovarian cancer. But these procedures also make it impossible to become pregnant. Women considering this surgery may wait until their 30s or until they're done having children.
Prevention
Surgery is the only way to prevent cancer in people with Lynch syndrome. No other measures have been proved to reduce your risk. However, taking care of yourself through diet, exercise and other lifestyle changes can help improve your overall health.
Take control of your health by trying to:
- Eat a healthy diet full of fruits and vegetables. Choose a variety of fruits and vegetables for your diet. Select whole-grain products when possible.
- Exercise regularly. Aim for at least 30 minutes of exercise most days of the week. If you haven't been active, talk to your doctor before you begin an exercise program. Try gentle exercises like walking or biking to get started.
- Maintain a healthy weight. A healthy diet and regular exercise can help you maintain a healthy weight. If you need to lose weight, talk with your doctor about your options. Eating less and exercising more can help you lose weight. Aim to lose 1 or 2 pounds a week.
- Quit smoking. Smoking increases your risk of several types of cancer and other health conditions. If you smoke, quit. Your doctor can recommend strategies to help you quit. You have many options, such as nicotine replacement products, medications and support groups. If you don't smoke, don't start.
Coping and support
Knowing that you or your family members have an increased risk of cancer can be stressful. Helpful ways to cope might include:
- Find out all you can about Lynch syndrome. Write down all of your questions about Lynch syndrome and ask them at your next appointment with your doctor or genetic counselor. Ask your health care team for further sources of information. Learning about Lynch syndrome can help you feel more confident when making decisions about your health.
- Take care of yourself. Knowing that you have an increased risk of cancer can make you feel as though you can't control your health. But control what you can. For instance, choose a healthy diet, exercise regularly and get enough sleep so that you wake feeling rested. Go to all of your scheduled medical appointments, including your cancer-screening exams.
- Connect with others. Find friends and family with whom you can discuss your fears. Talking with others can help you cope. Find other trusted people you can talk with, such as clergy members. Ask your doctor for a referral to a therapist who can help you understand your feelings.
Last Updated: 01/23/2008
