Breast cancer is more likely to spread during sleep

The person is Christa Lesté-Lasserre.

Breast cancer cells spread to other parts of the body mostly at night while people are sleeping and not continuously throughout the day as previously thought.

Researchers warn that this doesn't mean that people with cancer should avoid sleeping to stop the spread of the disease. The best time of day to give cancer therapies could be the reason for the discovery.

He says that most cancer treatments aren't designed to target a specific time, but to attack the tumours at any time. Treatments need to be done better now that we know what happens at different times.

When they ran a study on breast cancer that had spread to other organs, they found an unexpected trend.

There were 30 women with breast cancer who weren't undergoing treatment. The scientists took blood samples in the middle of the night.

78 percent of the CTCs were found when the women were asleep.

Some cancers are being treated with vaccines tailored to the genetic make up of an individual's tumours, a strategy that is looking more hopeful.

The researchers ran the same tests on mice that had been treated for breast cancer. Depending on the cancer type, between 87 and 99 per cent of the cells came from samples taken during sleep. They were more likely to form a new tumours in samples from sleeping mice than they were from awake ones.

The findings make sense even though they are surprising. The immune system is affected by the sleep-Wake cycle. He says that cancer tumours were thought not to follow that rhythm.

There are still many unanswered questions after the new findings. The peak of sleep is a certain rhythm. We don't know if sleeping more or less would help this.

The journal is titled Nature.

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