散发性结直肠癌组织病理学特征及微卫星不稳定状态分析400例

Screening of MSI detection loci and their heterogeneity in East Asian colorectal cancer patients

OBJECTIVE

This study aims to screen the MSI detection loci suitable for the East Asian colorectal cancer patients. and explore its intratumoral heterogeneity.

METHODS

A total of 271 pathological tissues specimens of colorectal cancer were collected. The MSI status was detected using different PCR reagent kits with different detection loci. Then, the results were compared with the immunohistochemical (IHC) staining results. Microdissection of pathological tissues specimens detected to be MSI-H was performed to examine whether there was intratumoral heterogeneity of MSI status.

RESULTS

Thirty-nine out of 271 cases were dMMR. dMMR occurred mostly in patients with right-hemi colon cancer (P < 0.0001). Compared with dMMR patients, the clinical stages of pMMR patients were more inclined to be in the late stage with lymph node metastasis (P < 0.0001). MSI-H tumors were significantly associated with KRAS mutation (P = 0.036) and PD-L1 expression (P = 0.038). Compared with Promega panel and 24-locus detection, the consistency between NCI MSI panel and IHC staining results were the highest with the Kappa value of 0.850. The sensitivity of detection decreased from 87.18% to 56.41% with the increase in detection loci. Single locus analysis showed that the first two loci with the highest sensitivity were both mononucleotide loci, namely, BAT-26 (95.45%) and BAT-25 (86.36%). The dinucleotide locus with highest sensitivity was D2S123 (50%). The main detection loci of MSI-H showed no intratumoral heterogeneity.

CONCLUSION

The combination of 2 mononucleotide loci (BAT25, BAT26) and 3 dinucleotide loci (D2S123, D5S346, D17S250) might be the most suitable loci for MSI detection in East Asian population. There is no intratumoral heterogeneity in the main MSI loci.

The clinicopathological features and prognosis of tumor MSI in East Asian colorectal cancer patients using NCI panel

AIM

To compare test results obtained from a PCR assay for the National Cancer Institute (NCI) five loci criteria for detecting microsatellite instability (MSI) with those obtained from immunohistochemistry of mismatch repair and a five-mononucleotide site amplification system in East Asian patients with colorectal cancer.

PATIENTS & METHODS

 A total of 245 East Asian patients with colorectal cancer were studied retrospectively at our institution.

RESULTS

The consistency of the NCI panel PCR method compared with detection of mismatch repair protein expression by immunohistochemistry was 0.898. High level MSI (MSI-H) status was correlated with the Tumor, Node, Metastasis stage, tumor location site, metastasis, tumor grade, mucinous histological type and BRAF-type mutations.

CONCLUSION

The NCI panel PCR assay has excellent sensitivity and specificity for detecting MSI in an East Asian population.