For cancer to metastasize to other organs, cancer cells must first break away from the primary tumor and enter the bloodstream. A study published yesterday (June 22) in Nature suggests that this dissemination mostly occurs while its host sleeps. The authors observed that circulating tumor cells (CTCs)—those that have detached from the tumor to migrate to distant organs—were found in significantly higher numbers in blood samples collected while breast cancer patients and mice were in their resting period compared to their active one.
Catherine Alix-Panabières, a cancer researcher at University Hospital of Montpellier in France who did not participate in this study but is currently collaborating with one of the authors on a different project, says she is happy to see these new “very strong data” supporting the role of circadian rhythms in tumor dissemination. She and her colleagues had previously speculated that circulating tumor cells could be influenced by ...