The stepwise evolution of colon cancer from a single genetic spark

Science · Published 25 October 2026 Swipe more like this →

In short: Most colorectal cancers don't appear overnight; they follow a predictable, multi-hit progression from healthy tissue to benign polyps and finally to invasive tumors. By tracing these specific molecular milestones, scientists can decode how a few broken genes eventually orchestrate the development of one of the world's most common malignancies.

The 'adenoma-carcinoma sequence' describes the primary mechanism for approximately 85% to 90% of colorectal cancers (CRC). This process involves a stepwise accumulation of genetic and epigenetic alterations. A foundational model proposed by Fearon and Vogelstein in 1988 identified sentinel molecular events that occur as normal mucosa transforms into premalignant polyps, which then progress into invasive disease.

Research highlights several distinct pathways driving this instability: Chromosomal Instability (CIN), Microsatellite Instability (MSI), and the serrated neoplasia pathway. These mechanisms can overlap, but they often result in different clinical outcomes. For instance, tumors are categorized as 'hypermutated' if they possess more than 12 mutations per 106 bases, while 'non-hypermutated' tumors have fewer than 8.24 mutations per 106 bases.

Modern transcriptomic profiling has revealed that this progression is accompanied by a sustained enhancement of the immune response. Specific genes like WARS1 show significant upregulation during the transition from normal tissue to cancer, correlating with increased immune cell infiltration and stromal activation. However, these markers can shift as the disease advances; for example, WARS1 levels may decline as CRC progresses from stage I to IV, potentially linking its expression to metastasis.

Understanding these pathways is critical because CRC remains a heterogeneous disease. While the traditional model supports clinical practices like removing adenomas to reduce invasive neoplasia, the natural history of polyps and carcinomas is extremely variable. Continued research into DNA mismatch repair, DNA methylation, and m6A regulators aims to refine these classifications for more effective surveillance.

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