In fact, it was a coincidental finding in that sense that put the researchers on the right track. “Some of my colleagues work early in the morning or late at night, sometimes they also analyze blood at unusual hours,” Aceto said. The researchers were surprised to find that samples taken at different times of the day had vastly different levels of freely circulating cancer cells.
Another clue was the surprisingly high number of cancer cells found per unit of blood from mice, compared to humans. The reason for this is that mice are nocturnal animals that sleep during the day, while researchers take most of their samples during the day.
“In our view, these findings may indicate that health care providers should systematically record the time when they perform biopsies,” Aceto said. “That can help make the data really comparable.”
As a next step, the researchers want to explore how their findings can be integrated into existing cancer treatments to optimize the therapies.
As part of further studies with patients, Professor Aceto wants to investigate whether different cancers behave in the same way as breast cancer and whether existing therapies can be made more successful if patients are treated at different times.
The study by researchers from ETH Zurich, Universitätsspital Basel and Universität Basel is published in Nature† This article is based on a press release from ETH Zurich.