Hereditary nonpolyposis colorectal cancer (HNPCC) syndrome, also known as Lynch syndrome, was first described more than 100 years ago. It is the most common of the recognized inherited colorectal cancer syndromes.
Symptoms of Lynch Syndrome
Many patients with colorectal cancer experience no symptoms in the early stages of the disease. Symptoms may not appear until the disease is in an advanced stage. Routine colorectal screening and understanding the risk factors are important.
Symptoms of colorectal cancer are similar to symptoms of other colon diseases. If you experience the following symptoms, see your physician:
- Bloody stool
- Unexplained diarrhea
- A long period of constipation
- Abdominal cramps
- Decrease in size or caliber of stool
- Gas pain, bloating, fullness
- Unexplained weight loss
- Lethargy and vomiting
Lynch Syndrome Diagnosis at Johns Hopkins
Early diagnosis is crucial for early detection and treatment of colorectal cancer. You should have regular screenings — when to begin depends on your family and medical history.
People at risk for Lynch syndrome usually have a family history of two successive generations of colorectal cancer, or at least one generation with colorectal cancer and one generation with polyps.
Men and women at risk need a colon examination; women should also have yearly endometrial and ovarian screenings. Your doctor will discuss with you your specific examination guidelines.
Diagnostic procedures include:
- Genetic testing
- Microsatellite instability testing
Mutations, or changes, of one of five different genes are responsible for most cases of Lynch syndrome. If you have a family history of Lynch syndrome, you can have a gene test to determine whether you are at risk for developing cancer.
A gene test is performed by obtaining a small blood sample. If you do have the gene mutation, you will know to schedule annual colonoscopies and get regular screenings. If you do not, you can avoid unnecessary examinations.
Microsatellite Instability Testing
Microsatellite instability testing is used as a screening test to see how likely it is that your cancer was caused by one of the Lynch syndrome genes. If your test was positive, then the cancer is probably due to a gene mutation, and you can pursue genetic blood testing.
A colonoscopy is the preferred method for diagnosing Lynch syndrome. A colonoscopy is the best way to detect polyps or cancer and allows your doctor to see the entire bowel. During a colonoscopy:
- Your colon must be clear of stool so there is good visibility. Preparations may include a liquid diet, enema and laxatives.
- You are sedated before the procedure.
- Your doctor inserts the colonoscope through the rectum and into the anus and large intestine, and checks to see if cancer or polyps are present.
- Biopsy forceps may be inserted through the scope in order to remove a small sample of tissue for further analysis.
- If there is a polyp, it can be removed through the colonoscope.
- The procedure may cause some cramping or discomfort.
Lynch Syndrome Treatment at Johns Hopkins
Your treatment will depend on the findings during the examination. Your doctor may be able to remove the polyps endoscopically, or surgery maybe recommended. Learn more about Lynch syndrome treatment at Johns Hopkins.