Researchers at the University of Chicago have adapted ancient DNA techniques to recover usable genetic information from medical specimens as old as 90 years. The method may give pathologists and researchers new opportunities to examine how diseases – including cancer – have changed over time. The work was presented at the Association for Molecular Pathology (AMP) 2025 Annual Meeting & Expo.
DNA in archived formalin-fixed paraffin-embedded (FFPE) tissue degrades with age, making sequencing difficult. As a result, most modern genomic analyses rely on recent specimens, limiting the ability to explore historical patterns of disease. To test whether these barriers could be overcome, the team analyzed colorectal cancer samples collected between 1932 and 2023. The disease was chosen because its incidence in younger adults has risen sharply; a 35-year-old today faces about twice the risk compared with the same age group in 1985.
The researchers optimized deparaffinization and DNA extraction to retain even highly fragmented DNA. They then used library preparation and bioinformatics tools normally reserved for archaeological specimens. This enabled missing or damaged DNA fragments to be reconstructed and aligned to the human genome. The team applied both whole-genome sequencing and a targeted cancer gene panel, modifying each protocol to preserve small DNA fragments that conventional methods often discard.
In addition to tumor DNA, the researchers examined microbial DNA present in the samples. They detected both expected gut bacteria and species previously linked to colorectal cancer. The group is now refining these analyses to better understand how microbial signatures may have shifted across decades.
The study authors suggest the approach could help researchers investigate long-term trends in tumor biology and the microbiome. By enabling genomic study of older archived specimens, the method may support efforts to track how disease features evolve over time and provide historical context for current diagnostic observations.
Although the work is currently focused on colorectal cancer, the researchers note that the same approach could be applied to archived specimens from other diseases. The study demonstrates that pathology archives – long valued for education and case comparison – may also serve as sources of analyzable genomic material when paired with adapted ancient DNA workflows.
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