Abstract:

Objective

Comparative analysis of clinicopathological characteristics and prognostic outcomes between sporadic microsatellite instability （MSI） colorectal cancer and Lynch Syndrome （LS）-associated cases in Chinese patients.

Methods

A total of 338 consecutive postoperative cases of MSI colorectal cancer diagnosed at the Cancer Hospital of the Chinese Academy of Medical Sciences from January 2015 to December 2017 were collected， including 105 cases of LS and 233 cases of sporadic MSI colorectal cancer. The clinicopathological characteristics were retrospectively analyzed， and relevant literature was reviewed.

Results

LS patients were significantly younger at the time of diagnosis compared to sporadic MSI colorectal cancer patients （t=4.179， P＜0.001）， and the type of mismatch repair protein deficiency tended to be more of type 3 （χ²=28.036， P＜0.001） or type 4 （χ²=4.325， P=0.038）. Sporadic MSI patients were more likely to experience promoter methylation （χ²=22.388， P＜0.001） and BRAF mutation （χ²=13.005， P＜0.001）.There was no significant difference in histological morphology between the two groups， and the differences in overall survival （χ²=1.053， P=0.305） and progress-free survival （χ²=0.008， P=0.928） were not statistically significant. High-risk histological components such as micropapillary and signet ring cells were significant independent prognostic factors for progress-free survival in MSI colorectal cancer patients （HR=4.075， P＜0.05）.

Conclusion

LS and sporadic MSI colorectal cancers display differences in clinicopathological characteristics， and the molecular mechanisms behind their varied responses to immunotherapy warrant further investigation.

Key words: Colorectal neoplasms, Lynch syndrome, Sporadic microsatellite instability colorectal cancer, Clinicopathological features, Immunotherapy