While the Body Rests, Breast Cancer Spreads More Aggressively

More cancer cells are shed from primary tumors when individuals are asleep than when they’re awake, according to observations in mouse models and a small cohort of breast cancer patients.

Written byAlejandra Manjarrez, PhD
| 4 min read
Artist’s rendition of metastatic cancer cells with yellow nuclei and green cell bodies extending into blue tendrils.
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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 ...

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  • alejandra manjarrez

    Alejandra Manjarrez is a freelance science journalist who contributes to The Scientist. She has a PhD in systems biology from ETH Zurich and a master’s in molecular biology from Utrecht University. After years studying bacteria in a lab, she now spends most of her days reading, writing, and hunting science stories, either while traveling or visiting random libraries around the world. Her work has also appeared in Hakai, The Atlantic, and Lab Times.

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