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e-Posters

10P - Clinical and morphological pattern of malignant tumors with microsatellite instability

Date

06 Oct 2021

Session

e-Posters

Presenters

Aram Musaelyan

Citation

Annals of Oncology (2021) 32 (suppl_6): S1345-S1371. 10.1016/annonc/annonc740

Authors

A.A. Musaelyan1, S. Lapin2, V. Nazarov2, S. Vorobyev3, A. Zakharenko2, S.V. Orlov2

Author affiliations

  • 1 Research Institute of Medical Primatology, Sochi/RU
  • 2 Pavlov First Saint Petersburg State Medical University, 197022 - Saint Petersburg/RU
  • 3 National Center for Clinical Morphological Diagnostics, 192283 - Saint Petersburg/RU
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Abstract 10P

Background

Solid tumors with microsatellite instability (MSI), regardless of location, are highly susceptible to immune checkpoint inhibitors. The aim of the study was to investigate clinical and morphological features of tumors with MSI.

Methods

The study included 787 tumor samples of the following localizations: 530- colorectal cancer (CRC), 95- endometrial carcinoma (EC), 87- gastric cancer (GC), 20- ovarian cancer, 18- pancreatic cancer, 15- cervical cancer, 15- esophageal cancer, 7- cancers of unknown primary site. The study of MSI was carried out using fragment analysis by determining mononucleotide markers: BAT-25, BAT-26, NR-21, NR-24, NR-27. Data of preoperative level of CEA and CA19-9 were obtained in 185 patients with CRC.

Results

The prevalence of MSI in CRC was 6.8%, in EC- 27.4%, in GC - 6.9%, in ovarian cancer - 5%. MSI was not found in other localizations. The characteristic clinical and morphological features of MSI-positive CRC were younger age (p=0.032), right-sided localization (p<0.0001), presence of multiple primary tumors (p=0.041), absence of distant metastases (p=0.013), presence of carcinoma G3 (p=0.0008), mucinous component (p<0.0001), Crohn-like reaction (p=0.0063) and tumor-infiltrating lymphocytes (p<0.0001). Also, in patients with CRC with MSI, the preoperative level of CEA was lower than in patients with MSS tumors: the median was 2.0 ngml (interquartile range (IQR): 0.7-3.4; n=20) and 3.9 ng/ml (IQR: 1.1-13.1; n=165), respectively (p=0.0061). No differences in smoking status, tumor size and the presence of diseases associated with an increase of CEA were shown between the MSI and MSS CRC. For EC with MSI, there were the following features: endometrioid adenocarcinoma (p=0.017), high grade tumors (p=0.0054), presence of cribriform growth pattern (p=0.0084) and tumor-infiltrating lymphocytes (p=0.0019), as well as a higher level of mitotic activity (p=0.002). MSI-positive GC was more often found in women (p=0.033), was characterized by older age (p=0.001), distal tumor localization (p=0.022), presence of high-grade tumors (p=0.012) and tumor-infiltrating lymphocytes (p=0.009).

Conclusions

Common features for CRC, EC and GC with MSI are the presence of a high-grade tumors and tumor-infiltrating lymphocytes.

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.

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