Cancer cells are more likely to attack healthy parts of the body at night when the affected person is asleep, a new study has suggested. Cancer cells go through a process called metastasis, where they break away from the primary tumor and mix in the bloodstream to affect other parts of the body.
The study, published in Nature, was a joint effort of researchers from ETH Zurich, University of Basel and University Hospital Basel. It suggests that these cancer cells have high activity in the bloodstream when the affected person sleeps at night. Performed on breast cancer patients, the team of researchers found that the circulating tumor cells (CTCs) are significantly higher in number in the bloodstream at night than during the day.
“If the affected person sleeps, the tumor awakens,” Nicola Aceto, professor at ETH Zurich, summarized in a statement. The researchers included 30 female cancer patients and studied the activity of CTCs in them. They found that not only does the spread increase when the host is asleep, the tumor also divides faster during that time. The CTCs gain more potential at night to effectively enjoy metastases.
Researchers found that the escape of the CTCs from the original tumor into the bloodstream was controlled by melatonin, a hormone that sets the rhythm of day and night for the body. The study also provided insight into how the timing of tests and samples could influence the oncologists’ findings.
“Some of my colleagues work early in the morning or late at night. Sometimes they also analyze blood at unusual hours,” Aceto says. It was a miracle how the circulating tumor cells showed a varied composition depending on the time of day.
According to Aceto, the research indicates that healthcare professionals should systematically record the time at which they perform biopsies.
The study also lays the groundwork for several potential adjustments in cancer treatments. The next thing researchers want to investigate is whether existing therapies can be made more effective if they are done at different times of the day.
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