Breast cancer tumors apparently increase their activity at night and secrete more metastatic cancer cells than during the day. This is reported by a team led by biotechnologist Nicola Aceto, Professor of Molecular Oncology at ETH Zurich, in the journal “Nature”.
The Swiss researchers, together with colleagues from the University and the University Hospital Basel, were able to demonstrate the day-night pattern of breast cancer in 30 cancer patients and in mouse models. “If the affected person sleeps, the tumor wakes up,” says Aceto, summarizing the study results.
Tumor cells in the blood form offshoots
The study focused on the so-called circulating tumor cells. These are cells that have been detached from the original tumor and circulate in the blood. Some of them form offshoots in other organs, i.e. metastases. These are responsible for up to 90 percent of all deaths caused by cancer.
Cancer cells establish themselves as metastases at night
As the researchers note, tumors not only secrete more circulating cancer cells in the resting phase. Rather, the cancer cells released at night tend to eventually establish themselves as metastases. The dynamics of circulating cancer cells are dictated by important hormones in the sleep-wake cycle, such as melatonin, the study says.
Valuable information for diagnostics
According to the researchers, the findings offer valuable information for diagnostics. Accordingly, it could be helpful, for example, to carry out biopsies at strictly controlled times in order to ensure the comparability of the data. Cancer treatments could also potentially be improved if they were tuned to work maximally during sleep.
Further studies necessary
In an article accompanying the study, Harrison Ball and Sunitha Nagrath of the University of Michigan write that the work of Aceto and his team paints a “remarkable picture”. However, they note that the results need to be tested in large clinical trials before they can be used in clinical practice. In addition, she believes it would be interesting to see whether the observed 24-hour rhythm also occurs in tumor types other than breast cancer.