Researchers find that breast cancer grows at night


  • Almost one in eight women will develop breast cancer in her lifetime.
  • About 5% of breast cancers are linked to a genetic predisposition.

So far, there is little research that has looked at when the most common malignancy in women, namely breast cancer, releases cancer cells, which travel through the body via blood vessels. and form new tumors in other organs. Some researchers have assumed that these cells are permanently released. But according to work published in the journal Nature, June 22, metastatic spread of breast cancer accelerates during sleep. To reach this conclusion, researchers at the University Hospital of Basel in Switzerland conducted their study with 30 women with cancer and on mouse models.

The “leakage” of cancer cells

“When the affected person is asleep, the tumor wakes up”, summarized Nicola Aceto, author of the work, in a press release. Clearly, the tumor generates more circulating cancer cells when the body is asleep. Cells that detach from the tumor at night also divide more rapidly and therefore have a higher potential for metastasis formation, compared to circulating cells that detach from the tumor during the day.

“Overall, we find that key circadian hormones such as melatonin, testosterone and glucocorticoids dictate the production dynamics of circulating tumor cells and therefore insulin directly promotes cell proliferation. tumors in vivo, but in a time-dependent manner. Thus, the spontaneous production of cancer cells with a high propensity to metastasize does not occur continuously, but is concentrated in the resting phase of the affected person”can we read in the results of the study.

Pay attention to exam times

According to the authors, this discovery could significantly change the way cancer is diagnosed and treated in the future. They said the time at which tumor or blood samples were taken for diagnosis could influence oncologists’ conclusions. “Some of my colleagues work early in the morning or late at night, sometimes they also test blood at odd hours. (…) These results may indicate the need for health professionals to systematically record the time at which they do the biopsies. That could help make the data really comparable,” explained Nicola Aceto.

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