{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,11,10]],"date-time":"2026-11-10T11:09:06Z","timestamp":1794308946333,"version":"4.9.0"},"reference-count":26,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2021,8,20]],"date-time":"2021-08-20T00:00:00Z","timestamp":1629417600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Medicina"],"abstract":"<jats:p>Background and Objectives: Colorectal cancer (CRC) can be classified as mismatch-repair-deficient (dMMR) with high levels of microsatellite instability (MSI-H), or mismatch-repair-proficient (pMMR) and microsatellite stable (MSS). Approximately 15% of patients have microsatellite instability (MSI). MSI-H tumors are associated with a high mutation burden. Monoclonal antibodies that block immune checkpoints can induce long-term durable responses in some patients. Pembrolizumab is the first checkpoint inhibitor approved in the EU to treat dMMR\u2013MSI-H metastatic CRC. Materials and Methods: Our study assesses the regional variability of MSI-H colorectal cancer tumors in Romania. Formalin-fixed, paraffin-embedded (FFPE) tissue blocks containing tumor samples from 90 patients diagnosed with colorectal cancer were collected from two tertiary referral Oncology Centers from Romania. Tissues were examined for the expression loss of MMR proteins (MLH1, PMS2, MSH2, MSH6) using immunohistochemistry or MSI status using polymerase chain reaction (PCR), respectively. Results: MSI-H was detected in 19 (21.1%) patients. MSI-H was located more in ascending colon (36.8% vs. 9.9%, p-value = 0.0039) and less in sigmoid (5.3% vs. 33.8%, p-value = 0.0136) than MSS patients. Most patients were stage II for MSI-H (42.1%) as well as for MSS (56.3%), with significant more G1 (40.9% vs. 15.8%, p-value = 0.0427) for MSS patients. Gender, N stage, and M stage were identified as significant prognostic factors in multivariate analysis. MSI status was not a statistically significant predictor neither in univariate analysis nor multivariate analysis. Conclusion: Considering the efficacy of PD-1 inhibitor in metastatic CRC with MSI-H or dMMR, and its recent approval in EU, it is increasingly important to understand the prevalence across tumor stage, histology, and demographics, since our study displayed higher regional MSI-H prevalence (21%) compared to the literature.<\/jats:p>","DOI":"10.3390\/medicina57080847","type":"journal-article","created":{"date-parts":[[2021,8,22]],"date-time":"2021-08-22T21:47:52Z","timestamp":1629668872000},"page":"847","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["An Insight into Deficient Mismatch Repair Colorectal Cancer Screening in a Romanian Population\u2014A Bi-Institutional Pilot Study"],"prefix":"10.3390","volume":"57","author":[{"given":"Cristina","family":"Lungulescu","sequence":"first","affiliation":[{"name":"Doctoral School, University of Medicine and Pharmacy Craiova, 2 Petru Rares Str., 200349 Craiova, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4708-6265","authenticated-orcid":false,"given":"Vlad Mihai","family":"Croitoru","sequence":"additional","affiliation":[{"name":"Department of Oncology, Fundeni Clinical Institute, 258 Fundeni Str., 022238 Bucharest, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Simona Ruxandra","family":"Volovat","sequence":"additional","affiliation":[{"name":"Department of Medical Oncology, University of Medicine and Pharmacy Grigore T Popa Iasi, 700115 Iasi, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Irina Mihaela","family":"Cazacu","sequence":"additional","affiliation":[{"name":"Department of Oncology, Fundeni Clinical Institute, 258 Fundeni Str., 022238 Bucharest, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1374-276X","authenticated-orcid":false,"given":"Adina","family":"Turcu-Stiolica","sequence":"additional","affiliation":[{"name":"Department of Pharmacoeconomics, University of Medicine and Pharmacy of Craiova, 2 Petru Rares Str., 200349 Craiova, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dan Ionut","family":"Gheonea","sequence":"additional","affiliation":[{"name":"Department of Gastroenterology, University of Medicine and Pharmacy Craiova, 2 Petru Rares Str., 200349 Craiova, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0926-4614","authenticated-orcid":false,"given":"Daniel","family":"Sur","sequence":"additional","affiliation":[{"name":"Department of Medical Oncology, The Oncology Institute \u201cProf. Dr. Ion Chiricu\u0163\u0103\u201d, 400015 Cluj-Napoca, Romania"},{"name":"11th Department of Medical Oncology, University of Medicine and Pharmacy \u201cIuliu Hatieganu\u201d, 400012 Cluj-Napoca, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Cristian Virgil","family":"Lungulescu","sequence":"additional","affiliation":[{"name":"Department of Oncology, University of Medicine and Pharmacy Craiova, 2 Petru Rares Str., 200349 Craiova, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,8,20]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"394","DOI":"10.3322\/caac.21492","article-title":"Global cancer statistics 2018: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries","volume":"68","author":"Bray","year":"2018","journal-title":"CA Cancer J. 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