Coexistence of Microsatellite Stable (MSS) and Instable Colorectal Cancer (CRC) Primary Colon Cancers: A Case Report and Brief Review of Literature

Abstract

Abstract Introduction/Objective Microsatellite stable (MSS) and Instable colorectal cancer (CRC) as primary colon cancers differ in their pathological features and biological behavior including response to treatment. In general, MSI-high CRC has a better prognosis and a more favorable response to treatment. To our knowledge, the co-occurrence of the microsatellite stable and unstable CRCs in the same person has not been reported in the literature. Herein, we present the case report of 78 year African American female who presented to us with this condition. Methods A literature search of publication up to March 2020 in PubMed was conducted on the occurrence of microsatellite stable and unstable CRCs in the same individual. The literature search was limited to English language only. The following words were used in the search engine of PubMed: “Microsatellite stable colorectal cancer + unstable colorectal cancer and colorectal cancer + same patient”. No articles were identified. Results A search using the terms “coexistence of MSS and MSI CRC in the same individual” identified 45 articles. No case report or article discussing the presence of coexisting MSS and MSI CRC in the same individual was identified Conclusion Identification of MSI CRC is important, as MSI may serve as a screening tool for detecting Lynch Syndrome, a prognostic marker for patient outcome, and as a predictive marker for response to chemotherapy and to immunotherapy. Whether coexistence of MSI and MSS favorably affects the prognosis of the disease is unknown.