Recent advancements in medical genetics and molecular biology are reflected in the modern understanding and approach to colorectal carcinoma (CRC). Understanding the cellular mechanisms and mutational patterns that promote carcinogenesis could enhance the predictive accuracy of the TNM classification. Furthermore, this will allow for a much more documented stratification and tailored oncological treatment. This paper presents an illustrative case of a relatively young patient (50 years old) with no family history of cancer who was diagnosed with four synchronous gastrointestinal (GI) adenocarcinomas displaying a wild type P53, negative BRAF testing, and mutated MLH1 and PMS2 proteins. This case report contributes to the relevant literature with a concise review of the role of micro-satellite instability (MSI), chromosomal instability (CIN), and CpG island methylator phenotype (CIMP) in carcinogenesis, hereditary and sporadic gastrointestinal cancers, a discussion over the importance of molecular sub-typing in predicting long term outcomes and choosing the most suitable adjuvant treatment regimen
