Overview

Lynch syndrome is an inherited condition that increases your risk of colon cancer, endometrial cancer and several other cancers. Lynch syndrome has historically been known as hereditary nonpolyposis colorectal cancer (HNPCC).

A number of inherited syndromes can increase your risk of colon cancer or endometrial cancer, but Lynch syndrome is the most common. Doctors estimate that around 3 out of every 100 colon cancers or endometrial cancers are caused by Lynch syndrome.

Families that have Lynch syndrome usually have more instances of colon cancer or endometrial cancer than would typically be expected. Lynch syndrome also causes cancers to occur at an earlier age than they might in the general population.

Source: http://www.mayoclinic.com

Symptoms

People with Lynch syndrome may experience:

• Colon cancer that occurs at a younger age, especially before age 50
• A family history of colon cancer that occurs at a young age
• A family history of cancer that affects the uterus (endometrial cancer)
• A family history of other related cancers, including ovarian cancer, kidney cancer, stomach cancer, small intestine cancer, liver cancer, sweat gland cancer (sebaceous carcinoma) and other cancers

When to see a doctor

If you have concerns about your family history of colon or endometrial cancer, bring them up with your doctor. Together, you and your doctor may consider having a genetic 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 about the disease and help you understand whether genetic testing is appropriate for you.

Source: http://www.mayoclinic.com

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 risk of Lynch syndrome is the same whether the gene mutation carrier is the mother or father or whether the child is a son or daughter.

How gene mutations cause cancer

The genes affected in Lynch syndrome are responsible for correcting changes in the genetic code (mismatch repair genes).

Your genes contain DNA, which carries instructions for every chemical process in your 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 the cells of 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 cause the cells to become cancerous.

Source: http://www.mayoclinic.com

Diagnosis

If it's suspected that you have Lynch syndrome, your doctor may ask you questions about your family history of colon cancer, endometrial cancer and other cancers. This may lead to other tests and procedures to diagnose Lynch syndrome.

Family history

Your doctor may refer you for further Lynch syndrome evaluation if you have:

• Multiple relatives with any Lynch-associated tumors, including colorectal cancer. Examples of other Lynch-associated tumors include those affecting the endometrium, ovaries, stomach, small intestine, kidney, brain or liver.
• Family members diagnosed with cancer at ages that are younger than the average for their type of cancer.
• More than one generation of family affected by a type of cancer.

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 and sometimes from other tumors can be used for tumor testing.

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 gene caused the cancer.
• Microsatellite instability (MSI) testing. Microsatellites are sequences of DNA. In people with Lynch syndrome, there may be errors or instability in these sequences in the tumor cells.

Positive IHC or MSI test results indicate that you have malfunctions in the genes that are connected to Lynch syndrome. But the results can't tell you whether you have Lynch syndrome because some people develop these gene mutations only in their cancer cells.

People with Lynch syndrome have these gene mutations in all of their cells. Genetic testing can determine whether you have these mutations.

Increasingly, IHC or MSI testing is being offered to anyone diagnosed with colon cancer or endometrial cancer to look for Lynch syndrome. Doctors hope this will help identify families with Lynch syndrome that don't meet the usual criteria for genetic testing.

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.

Genetic testing may show:

• A positive genetic test result. A positive result, meaning that a gene mutation was discovered, doesn't indicate that you have cancer or will get cancer. But it does mean that your lifetime risk of developing certain cancers is increased.

  How much your risk is increased depends on which gene is mutated in your family and whether you undergo cancer screening or risk-reducing operations to decrease your risk of cancer. Your genetic counselor can explain your individual risk to you based on your results.

• A negative genetic test result. A negative result, meaning that a gene mutation wasn't found, indicates that you likely don't have Lynch syndrome. You may still have an increased risk of cancer, though, if you have a strong family history of cancer.
• A gene variation of unknown significance. Genetic tests don't always give you a yes or no answer about your cancer risk. Sometimes genetic testing reveals a gene variation with an unknown significance. Your genetic counselor can explain the implications of this result to you.

Sometimes genetic testing for Lynch syndrome is part of a test for multiple cancer-related genetic mutations. Your genetic counselor can discuss the benefits and risks of genetic testing with you. He or she can explain what genetic testing can tell you and what it can't.

Source: http://www.mayoclinic.com

Complications

Beyond causing complications for your health, a genetic disorder such as Lynch syndrome may raise other concerns. A genetic counselor is trained to help you navigate the areas of your life that may be 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 have questions about whether being diagnosed with Lynch syndrome will make it difficult to change jobs or health insurance providers in the future. A genetic counselor can explain the laws that may protect you.
• Your children. If you have Lynch syndrome, your children have a risk of inheriting your genetic mutations. If one parent carries a genetic mutation for Lynch syndrome, each child has a 50 percent chance of inheriting that mutation. A genetic counselor can help you develop a plan for discussing this with your children, including how and when to tell them and when they should consider testing.
• Your extended family. A Lynch syndrome diagnosis has implications for your entire family, as many other blood relatives may have a chance of having Lynch syndrome. A genetic counselor can assist you in finding the best way to tell family members that you're having genetic testing and what that the results mean.

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 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 if 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. Connect with other people with Lynch syndrome through advocacy groups such as Lynch Syndrome International. 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.

Source: http://www.mayoclinic.com