Heidi Ledford in Nature:
Deep in the basement archives of London's Great Ormond Street Hospital for Children reside the patient records that cancer researcher Sam Behjati hopes will put the hospital's past to work for the future. On 2 May, he and his colleagues published the result: DNA sequences from the genomes of three childhood tumour samples collected at the facility almost a century ago1. Those historic cells help to address a modern problem: the small number of tumour samples from rare cancers that are available for researchers to sequence. Behjati knows this problem well. At the Wellcome Trust Sanger Institute in Hinxton, UK, he tracks the genomic miswiring that can lead to rare childhood cancers. And as someone who also treats patients, he has been frustrated by the paucity of evidence backing up much of his practice. “The treatment regimens for children with rare cancers are essentially made up,” Behjati says. “If you’ve got three or four patients nationally, how are you ever going to conduct a reasonable clinical trial?” To expand the pool of samples that he could sequence, he decided in 2014 to harness advances in genome sequencing that had already made it possible to sequence DNA from pathology samples a few decades old. The hospital's 165-year archive of samples and patient records provided the opportunity to see how far back in time he could go.
The work highlights the wealth of material that is available in such archives, says Danielle Carrick, a programme director at the US National Cancer Institute in Rockville, Maryland. Mining such archives can expand the options for studying rare conditions and understudied ethnic populations, she notes, and make large, population-scale studies possible. Researchers have analysed DNA from much older specimens: fragments of genome sequence have been used to study ancient human populations from hundreds of thousands of years ago. But DNA tends to degrade over time, and cancer researchers need high-quality sequences to pinpoint the many individual mutations that can contribute to tumour growth.