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Lynch Syndrome

Lynch Syndrome

Lynch syndrome is an (autosomal) inherited cancer syndrome causing uterine, bowel, stomach and urinary tract cancers. Patients with Lynch syndrome have a 27% to 70% risk of developing uterine cancer and risk of 5% to 12% of developing ovarian cancer. Uncommon Lynch-related tumours include cancers of the renal pelvis, ureter, stomach, small bowel, bile duct, skin (sebaceous neoplasms), and brain (gliomas). 

Often, patients who carry Lynch syndrome are diagnosed with cancer at a younger than expected age, may develop additional cancers and know other family members who developed different types of cancer (stomach, bladder, bowel, uterus, ovarian).

Patients who were diagnosed with uterine cancer at 50 years of age or less have an 18% chance of carrying Lynch syndrome. These patients require regular screening (e.g. colonoscopies) for the other cancer types.

Patients who were diagnosed with Lynch-related bowel cancer have a 25% risk of developing subsequent uterine or ovarian cancer. In these patients prophylactic, risk-reducing surgery to remove uterus, tubes and ovaries can be life-saving. These operations are done laparoscopically (key hole) and virtually eliminate the risk of uterine and ovarian cancer.

Females with a Lynch-related endometrial cancer have a 40-times higher risk of developing colorectal cancer.

Females diagnosed with a Lynch-related colon cancer have a 28-times higher risk of developing endometrial cancer.

Why is it so important to diagnose Lynch?

Lynch patients must be screened for other cancers. Screening or risk-reducing prophylactic surgery can save lives.

First-degree relatives (offspring, siblings) of Lynch patients have a 50% risk to also carry Lynch. Upon confirmation of Lynch syndrome, first-degree relatives also require genetic testing.

Family history is a poor indicator about Lynch syndrome and 50% of patients with proven Lynch syndrome do not carry a family history. 

A missed diagnosis can cause someone cancer and treatment (surgery, chemotherapy, radiation treatment).

I routinely request Lynch testing in all patients with endometrial cancer who are less than 60 years of age, who are not obese or who demonstrate histopathological features often associated with Lynch syndrome (e.g. involvement of lower uterine segment or cervix, the presence of tumour infiltrating lymphocytes).  

The first step to diagnose Lynch is an immunohistochemical test that can be done from the surgical specimen from the original uterine or bowel cancer specimen. This test is not diagnostic. However, if the test is positive, confirmatory genetic testing should be instigated and requires a blood test. Referral to a Family Cancer Clinic or a clinical geneticist is recommended. 

Clinical management

1. Surveillance for ovarian cancer is unreliable and generally not recommended. Surveillance for uterine cancer can be done through endometrial sampling (Pipelle) (for premenopausal women) or through ultrasound (in postmenopausal women) but is also unreliable. Colonoscopy (every 1 to 2 years) from age 25 years (reduces colon cancer incidence and mortality by >60%) is reliable indeed and recommended. Annual urine cytology will detect early stages of bladder and ureteric cancers. 

2. Prevention: The oral contraceptive pill will reduce the risk of ovarian cancer by 50%. There is no established medication to prevent uterine cancer. 

3. Prophylactic surgery (laparoscopic hysterectomy) is the most effective way to eliminate the risk of uterine and ovarian cancer; it should be offered to all women who have completed childbearing or who are postmenopausal. It virtually eliminates the risk of developing uterine or ovarian cancer and should be performed by an experienced laparoscopic surgeon. Patients need to be medically fit to tolerate surgery, need to be aware of the most common risks and possible complications of surgery and require some investigations (blood tests, medical imaging) prior to surgery. 

For information about Lynch Syndrome Australia, which is a consumer group, click here

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