From the Guidelines
Lynch syndrome patients should undergo regular screening for colorectal cancer with colonoscopy starting at age 20-25 or 2-5 years before the earliest diagnosis in the family, and repeat every 1-2 years, as recommended by the American Gastroenterological Association Institute 1. This is crucial because Lynch syndrome is the most common heritable colorectal cancer syndrome, accounting for 2% to 3% of colorectal cancers, and has an estimated prevalence in the general population of 1 in 440 1. Key points to consider in managing Lynch syndrome include:
- Genetic testing is recommended for diagnosis, and family members should be tested if a mutation is found 1
- Women should also undergo endometrial and ovarian cancer screening starting at age 30-35 1
- Regular screening for other associated cancers may include upper endoscopy, urinalysis, and physical exams 1
- Risk-reducing options include prophylactic surgeries like colectomy or hysterectomy/oophorectomy for high-risk individuals 1
- Daily aspirin may reduce colorectal cancer risk, although this should be discussed with a healthcare provider 1 It's essential to note that Lynch syndrome follows an autosomal dominant inheritance pattern, meaning children of affected individuals have a 50% chance of inheriting the condition, making family genetic counseling essential for proper management 1. The most recent and highest quality study on this topic is from 2016, which emphasizes the importance of identifying patients with Lynch syndrome and providing them with appropriate surveillance and risk-reducing measures 1.
From the Research
Definition and Prevalence of Lynch Syndrome
- Lynch syndrome is an autosomal-dominant inherited cancer susceptibility syndrome caused by a germline mutation in one of the DNA mismatch repair genes 2.
- It is also known as hereditary nonpolyposis colorectal cancer (HNPCC) syndrome 2.
- Lynch syndrome is one of the most common cancer susceptibility syndromes, with individuals having a 50%-70% lifetime risk of colorectal cancer, 40%-60% risk of endometrial cancer, and increased risks of several other malignancies 3.
Screening and Diagnosis of Lynch Syndrome
- Screening for colorectal cancer (CRC) in Lynch syndrome enables early detection and likely cancer prevention 4.
- Current gynecologic cancer screening guidelines for women with Lynch syndrome include annual endometrial sampling and transvaginal ultrasonography beginning at age 30 to 35 years 2.
- A combination of family and personal medical history and tumor testing provides an efficient basis for diagnosing Lynch syndrome in women with endometrial cancer 2.
- Immunohistochemistry, microsatellite instability analysis, or direct gene sequencing can be used to identify individuals who harbor the well-characterized mismatch-repair gene mutations 5.
Clinical Implications and Management of Lynch Syndrome
- Diagnosing endometrial cancer patients with Lynch syndrome has important clinical implications for the individual and family members 2.
- Screening and prevention practices can decrease the likelihood of developing additional cancers 2.
- Combined colon and endometrial cancer screening is a patient-centered approach that is feasible, acceptable, and may improve adherence to Lynch syndrome screening recommendations 6.
- Universal screening of all colorectal and endometrial cancers for Lynch syndrome is recommended, along with genetic-counseling efforts, to lead to a cost-efficient and beneficial screening program 5, 3.