Objective: To evaluate the frequency of microsatellite instability (MSI) and absence of hMLH1/hMSH2 expression in young patients with colorectal cancer, and investigate their role in screening hereditary nonpolyposis colorectal cancer (HNPCC).
Method: Seventy-three young patients (below 40 years old) with colorectal cancer were examined for DNA mismatch repair deficiency by microsatellite testing and immunohistochemical detection of hMLH1/hMSH2 gene products.
Results: The frequency of MSI and absence rate of hMLH1/hMSH2 expression are 56.16% and 49.32% in these patients, respectively, which increased significantly with younger age for cancer diagnosis.
Conclusion: Defects in the DNA mismatch repair system are frequent in Chinese young patients with colorectal cancer. Microsatellite analysis and immunohistochemical detection are useful for efficient identification of HNPCC in these young patients.