Molecular Screening for Lynch Syndrome in Young Patients With Colorectal Adenomas

Area of Science:

• Gastroenterology
• Oncology
• Genetics

Background:

• Mismatch repair deficiency (dMMR) is a key indicator in colorectal cancer development.
• The prevalence of dMMR in adenomas of patients under 50 without known germline mutations is not well-established.
• Understanding dMMR frequency in this demographic is crucial for early cancer detection strategies.

Purpose of the Study:

• To determine the frequency of mismatch repair deficiency (dMMR) in colorectal adenomas from patients younger than 50 years.
• To assess the utility of routine polyp screening in identifying potential Lynch syndrome carriers in this age group.

Main Methods:

• Retrospective analysis of colonoscopy data from 2008-2013 at Memorial Sloan Kettering Cancer Center.
• Inclusion criteria: patients aged 18-49 with tubular, villous, or tubulovillous adenomas, excluding those with prior CRC, polyposis, or IBD.
• Immunohistochemistry staining for MLH1, MSH2, MSH6, and PMS2 proteins was performed on polyps.

Main Results:

• 208 patients with 266 polyps were analyzed; 259 polyps were suitable for staining.
• The majority of polyps were tubular adenomas (95%).
• A low frequency of dMMR (0.4%) was observed in one patient, a 42-year-old woman with a history of endometrial cancer.

Conclusions:

• The study found a very low incidence of mismatch repair deficiency (dMMR) in adenomas of patients under 50.
• Routine screening of polyps in this age group is not an effective method for detecting Lynch syndrome.
• Further research may be needed to identify optimal screening strategies for Lynch syndrome in younger populations.