The dark side of sleep: Accelerated breast cancer spread during sleep

BioNews Central | 08-01-2023
Illustration depicting circulating cancer cells.
Illustration depicting circulating cancer cells. Credit: © Giovanni_Cancemi – Depositphotos

Breast cancer is one of the most prevalent forms of cancer affecting approximately 2.3 million people worldwide each year. Early detection is crucial for successful treatment outcomes, as patients typically respond well when breast cancer is caught in its early stages. However, treatment becomes considerably more challenging when the cancer has already metastasized. Metastasis occurs when cancer cells break away from the primary tumor, enter the bloodstream, and establish new tumors in other organs.

Previously, it was assumed that tumors continuously release metastatic cells. However, a recent study by researchers from ETH Zurich, the University Hospital Basel, and the University of Basel has yielded surprising results. The study, published in the journal Nature, reveals that circulating cancer cells that later form metastases predominantly arise during the sleep phase of affected individuals.

Lead researcher Nicola Aceto, Professor of Molecular Oncology at ETH Zurich, summarizes the findings as follows: “When the affected person is asleep, the tumor awakens.” The study, involving 30 female cancer patients and mouse models, demonstrates that tumors generate a higher number of circulating cancer cells during sleep. Notably, cells that leave the tumor during the night exhibit faster division rates, increasing their potential to form metastases compared to cells released during the day.

The study also sheds light on the role of circadian rhythm-regulated hormones in controlling metastasis. Hormones like melatonin, which regulate our day-night cycles, influence the release of circulating cancer cells from the primary tumor. These findings raise questions about the widespread use of melatonin as a sleep aid and suggest a need for reconsideration, at least among cancer patients.

Moreover, the study also emphasizes the potential impact of biopsy timing on oncologists’ findings. The researchers found significant variations in circulating cancer cell levels depending on the time of day when samples were collected. This highlights the importance of systematically recording biopsy times to enhance data comparability and lead to more accurate analyses, ultimately benefiting patient care.

Moving forward, the researchers plan to incorporate these findings into existing cancer treatments to optimize therapy outcomes. They aim to investigate whether different types of cancer exhibit similar behavior to breast cancer and explore the potential for improving treatment success by administering therapies at specific times.

By unraveling the relationship between sleep, tumor activity, and metastasis, this study has opened new avenues for understanding and combating breast cancer. The implications extend beyond breast cancer treatment, potentially influencing diagnostic and therapeutic approaches to other types of cancer. Further research and clinical studies may lead to refinements in cancer therapies and improved patient outcomes on a wider scale.


This article is based on materials provided by ETH ZURICH.


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