Biomarkers in Colorectal Cancer: Clinically Relevant Diagnostic and Prognostic Molecular Features, and the Future of Precision Medicine

Colorectal cancer (CRC) is a major public health concern in the United States. It is currently the fourth most diagnosed cancer and, despite advancements in screening and treatment, the second leading cause of cancer-related deaths. Approximately 153,000 new cases are diagnosed annually, with over 53,000 deaths reported. Understanding the molecular and genetic underpinnings of CRC biomarkers plays a crucial role in diagnosis, prognosis, and treatment planning. Specific gene mutations, including MMR deficiency leading to high microsatellite instability (MSI), as well as several other common mutations in CRC, including APC, TP53, KRAS, NRAS, SMAD4, PIK3CA and BRAF, provide valuable insights into tumor biology, therapeutic resistance, and response to targeted therapies. This review explores the mutations and co-mutations most relevant to CRC, their prevalence, prognostic significance, and implications for precision oncology. By focusing on these genetic and epigenetic alterations, we aim to contextualize how biomarker-driven strategies are reshaping the management of CRC in both early and advanced disease settings.