Elevated Microsatellite Alterations at Selected Tetranucleotide repeats (EMAST) testing in colorectal cancer using the costeffective qiaxcel advanced platform

Objective: Elevated Microsatellite Alterations at Selected Tetranucleotide repeats (EMAST) is a type of microsatellite instability occurring in about 60% of colorectal cancers (CRCs) and is associated with metastases and decreased patient survival. Fluorescent capillary sequencers, as most common EMAST detection technique, are relatively time-consuming and expensive. This study was conducted to examine the prevalence of EMAST in Iranian CRC patients using QiaXcel Advanced platform without the need to fluorescent primers, a technique that overcomes the main shortcomings of fluorescent capillary sequencers. Patients and Methods: EMAST status was analyzed in 183 Iranian FFPE (Formalin Fixed Paraffin Embedded) CRC samples using QiaXcel Advanced system (Qiagen, Hilden, Germany) based on capillary electrophoresis. D20S82, D20S85, D9S242, D8S321, and MYCL1 were included as common tetranucleotide markers. Results: A total of 75 patients (41.0%) had EMAST+ CRC. D20S85 was the most frequent marker (29.5%). Coincidence of instability at D8S321 and D20S85 markers were the most frequent type of instability (5.5%) and the distal colon had the highest number of EMAST+ cases (34.3%). Conclusions: Using QiaXcel Advanced system, EMAST were observed in 41.0% of Iranian CRCs. Due to the importance of EMAST in cancer progression, this fast and cost-effective PCR-based method can improve the clinical management of CRC that may further modify the patient outcome.