Lynch syndrome genetic testing

Overview

Lynch syndrome is a genetic condition that increases a person's chance of developing certain cancers, especially colorectal (bowel) cancer and endometrial (womb) cancer. Genetic testing looks for changes in specific genes that cause Lynch syndrome. Knowing your genetic status can help you and your doctor take steps to lower your cancer risk or catch cancer early.

Lynch syndrome is one of the most common inherited cancer syndromes, but it is still relatively uncommon. About 1 in 300 people may have Lynch syndrome, though many do not know it.

Lynch syndrome affects both men and women and can run in families. It does not discriminate by ethnicity, though some populations have a slightly higher frequency. A person with Lynch syndrome has a 50% chance of passing the gene change to each of their children.

Symptoms

Common symptoms

• Lynch syndrome itself does not cause symptoms. Instead, it increases the risk of developing certain cancers, which may cause symptoms later.

Symptoms in children

• Lynch syndrome is rarely diagnosed in children because the associated cancers usually develop in adulthood. However, children from families with Lynch syndrome may be tested to know their risk.

Symptoms in older adults

• Risk of cancer increases with age for people with Lynch syndrome. Early-onset cancers (before age 50) are more common, but Lynch syndrome can still affect older adults.

Causes

Main causes

• Lynch syndrome is caused by inherited changes (mutations) in one of several mismatch repair (MMR) genes: MLH1, MSH2, MSH6, PMS2, or EPCAM. These genes normally help fix mistakes that happen when DNA is copied.

Risk factors

• Family history of Lynch syndrome or cancers linked to it (especially colorectal or endometrial cancer diagnosed before age 50)
• Having a known gene mutation in the family
• Being from certain populations with higher carrier rates (e.g., people of Ashkenazi Jewish descent)

When to see a doctor

See a doctor urgently if:

• If you have any new, unexplained symptoms that might be due to cancer (e.g., blood in stool, unexplained weight loss, persistent abdominal pain), see a doctor urgently.

Book a routine appointment if:

• If you have a family history of Lynch syndrome or related cancers, talk to your doctor about whether genetic counseling and testing is right for you.

Diagnosis

Lynch syndrome is diagnosed through genetic testing. This is usually done after genetic counseling, where a specialist reviews your personal and family history to decide if testing is appropriate.

Tests that may be done

• Blood test to check for mutations in the MMR genes
• Saliva (spit) test – another way to collect a sample for genetic analysis
• Tumor testing (immunohistochemistry or microsatellite instability) – sometimes done first on a cancer sample to see if Lynch syndrome is likely

What to expect at your appointment

You will meet with a genetic counselor who will explain the process, risks, and benefits. If you choose to proceed, a blood or saliva sample is taken and sent to a lab. Results usually take a few weeks. The counselor will discuss the results with you and what they mean for you and your family.

Treatment

There is no cure for Lynch syndrome itself, but you can take steps to lower your cancer risk or catch cancer early. Treatment focuses on increased surveillance (screening) and, in some cases, preventive surgeries.

Self-care at home

• Follow recommended cancer screenings (e.g., colonoscopy every 1–2 years starting at age 25)
• Maintain a healthy lifestyle with a balanced diet, regular exercise, and avoiding smoking and excess alcohol
• Stay informed about your personal cancer risk and report any new symptoms promptly

Medical treatments

Medical management includes more frequent cancer screenings than the general population. For example, women may have yearly endometrial biopsies or transvaginal ultrasounds. If cancer develops, standard treatments like surgery, chemotherapy, or radiation may be used, tailored to your specific situation.

When is surgery considered?

Some people choose to have preventive (prophylactic) surgery, such as removal of the uterus and ovaries (hysterectomy and salpingo-oophorectomy) after they finish having children, to greatly reduce their risk of endometrial and ovarian cancer.

Living with this condition

Living with Lynch syndrome means staying proactive about your health. You will need to keep up with regular cancer screenings and communicate with your healthcare team. It is also important to share your genetic results with blood relatives so they can consider testing too.

Lifestyle tips

• Eat a diet rich in fruits, vegetables, and whole grains
• Exercise regularly (aim for at least 150 minutes of moderate activity per week)
• Avoid smoking and limit alcohol intake
• Manage stress through relaxation techniques or hobbies you enjoy

Diet and exercise

A healthy diet and regular exercise are not a substitute for medical care, but they can support overall health and may help lower cancer risk. Talk to your doctor about what exercise and diet plan is right for you.

Mental health and emotional wellbeing

Learning you have Lynch syndrome can be stressful and may cause worry about cancer. It is normal to feel anxious or overwhelmed. If these feelings affect your daily life, consider speaking with a mental health professional or joining a support group. If you have thoughts of harming yourself, contact a crisis helpline immediately.

Prevention

Lynch syndrome itself cannot be prevented because it is an inherited genetic condition. However, you can take steps to prevent or detect cancer early. The most important prevention measure is regular screening (surveillance) as recommended by your doctor.

Vaccines

There are no vaccines that prevent Lynch syndrome or directly prevent the cancers associated with it. However, some vaccines like the HPV vaccine can reduce the risk of certain cancers (e.g., cervical cancer) that may be relevant for people with Lynch syndrome.

Screening programmes

Colonoscopy is the main screening tool for colorectal cancer. For women, endometrial biopsy or ultrasound may be used. Your doctor will create a personalized screening schedule based on your gene mutation and family history.

Complications

If left untreated

• Without appropriate screening and surveillance, people with Lynch syndrome have a high risk of developing colorectal, endometrial, and other cancers, often at a younger age than the general population.
• If cancers are not caught early, they can spread and become harder to treat.

Long-term outlook

With regular monitoring and early detection, many cancers associated with Lynch syndrome can be found at an early stage when they are highly treatable. Most people with Lynch syndrome live full, healthy lives. Advances in cancer care continue to improve outcomes. The key is working closely with your healthcare team.

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