Abstract 1896: Clinicopathologic characteristics for elevated microsatellite alterations at selected tetranucleotie repeats (EMAST) in colorectal cancer of Korean patients

• Published in: Cancer research (Chicago, Ill.) Vol. 74; no. 19_Supplement; p. 1896
• Main Authors: Ihn, Myong Hoon, Kim, Duck-Woo, Lee, Hye Seung, Park, Kyoung Un, Lee, Soo Young, Oh, Heung-Kwon, Kang, Sung-Bum
• Format: Journal Article
• Language: English
• Published: 01.10.2014
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.AM2014-1896

Abstract Microsatellite instability (MSI) is a hallmark of tumors with mismatch repair deficiency. Recently, a different type of instability, elevated microsatellite alterations at selected tetranucleotide repeats (EMAST) has been reported in colorectal cancers. EMAST was reported to be associated with various clinicopathologic characteristics, including MSI status, race, tumor progression, and morphology and differentiation of tumor. However, contrary to MSI status which is well known prognostic and predictive marker in CRC, clinical implication of EMAST in CRC is still unclear. We evaluated EMAST and MSI status in 88 sporadic CRC cases using five markers (MYCL1, D9S242, D20S85, D8S321, and D20S82) for EMAST and Bethesda panel for MSI status, respectively. Clinicopathologic data of the patients were collected and analyzed. Tumors showing frameshifts in at least two or more EMAST markers were classified as EMAST-positive. Among 88 tumors, EMAST-positive tumors were 22 (25.0%) and MSI-H tumors were 32 (36.4%). EMAST-positive tumors showed proximal location of tumor (90.9% vs. 66.7%, p=0.029), less frequent loss of thymidylate synthase expression (4.5% vs. 34.8%, p=0.005), MSI-H (81.8% vs. 21.2%, p<0.001), nuclear heterogeneity of hMSH3 expression (77.3% vs. 51.5%, p=0.046) when compared with non-EMAST tumor. The other variables including age, gender, gross type and differentiation of tumor, a presence of stromal reaction, and tumor stage were not associated with EMAST status. In addition, overall and disease-free survival rate were similar between EMAST and non-EMAST tumor. In this study, MSI-H tumors showed very high frequency of EMAST-positive and clinical characteristics of EMAST and non-EMAST tumor were definitely different. Citation Format: Myong Hoon Ihn, Duck-Woo Kim, Hye Seung Lee, Kyoung Un Park, Soo Young Lee, Heung-Kwon Oh, Sung-Bum Kang. Clinicopathologic characteristics for elevated microsatellite alterations at selected tetranucleotie repeats (EMAST) in colorectal cancer of Korean patients. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1896. doi:10.1158/1538-7445.AM2014-1896