This finding may lead to changes in any future cancer treatment and diagnosis. When you are getting your Z’s, breast cancer metastases form more efficiently, a new study published in Nature has revealed. The researchers took blood from 30 breast cancer patients and mouse models at varying times. It was found that 78 percent of all circulating tumor cells (CTCs) found from the combined samples came from the samples taken during the typical sleeping phase. The research team also found that the cells that leave at night tend to have a higher chance to form metastases, which is when CTCs that break from the original tumor relocate to new places in the body to form new tumors. This is because compared to CTCs that leave during the day, the night cells tend to divide more quickly. “When the affected person is asleep, the tumour awakens,” said study leader Nicola Aceto in a statement. Before this study, there was limited data on when cancer typically sheds, and it was thought that it was done continuously. Cancer is one of the greatest threats to human health, and breast cancer is one of the most common forms of cancer – around 2.3 million cases worldwide annually. If breast cancer is caught early enough, patients typically respond well to treatment. However, treatment can be more difficult when metastasis has occurred. Metastasis is the cause of 90 percent of all cancer deaths. “Our research shows that the escape of circulating cancer cells from the original tumour is controlled by hormones such as melatonin, which determine our rhythms of day and night,” says Zoi Diamantopoulou, the study’s lead author. The results of this study also show that the time in which blood samples or tumor samples are taken may alter the results – this is what actually led to this study in the first place. “Some of my colleagues work early in the morning or late in the evening; sometimes they’ll also analyse blood at unusual hours," Aceto said. These unusual hours highlighted that levels of the circulating cancer cells differ depending on the time. “In our view, these findings may indicate the need for healthcare professionals to systematically record the time at which they perform biopsies,” Aceto says. “It may help to make the data truly comparable.” The mouse studies also highlighted something unusual: there was always a higher number of cancer cells found in mice compared to humans. Incidentally, mice are nocturnal animals, and the scientists usually collected the samples in the daytime when the mice were more likely to be sleeping. There is plenty of work still to do, and the scientists will now be trying to figure out how the findings can be incorporated into existing cancer treatments. The team also wants to investigate whether other cancer types act the same, and if current therapies are more successful if the patients are given them at different times. This finding may lead to significant changes in future cancer diagnosis and treatment. Source
