Night-time spread of breast cancer could inspire new therapies

BREAST cancer “wakes up” and spreads while people sleep, scientists have discovered in a breakthrough that could lead to the introduction of night-time biopsies and treatments.

Swiss scientists have observed that cancer cells that break away from the original tumour and travel elsewhere ramp up their activity during the sleep phase of affected individuals.

Until now, little attention has been paid to whether cancer acts differently depending on the time, with researchers assuming tumours release metastasising – spreading – cells continuously.

However, it now appears that they operate on a circadian rhythm, controlled by night-time hormones such as melatonin.

Cells that leave the tumour at night also divide more quickly and therefore have a higher potential to spread, compared with circulating cells that break away during the day.

Researchers believe the finding could significantly change the way cancer is diagnosed and treated in future. “Some of my colleagues work early in the morning or late in the evening and sometimes they’ll also analyse blood at unusual hours,” said study leader Nicola Aceto, professor of molecular oncology at ETH Zurich university.

“They found that when the affected person is asleep, the tumour awakens. In our view, these findings may indicate the need for healthcare professionals to systematically record the time at which they perform biopsies.”

Breast cancer is the most common cancer in Britain, accounting for 15 per cent of all new cancer cases, and around 55,900 people are diagnosed each year.

Survival has improved in recent years, driven by screening programmes, with 90 per cent of people still alive five years after diagnosis.

During the survey, researchers studied the tumour activity of 30 breast cancer patients as well as corroborating their findings in mice. They found that tumours generated more circulating cells during the hours of sleep.

“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 and a postdoctoral researcher at ETH Zurich.

The team now wants to investigate how the findings can be incorporated into existing cancer treatments.

As part of further studies with patients, Prof Aceto wants to investigate whether different types of cancer behave similarly to breast cancer and whether existing therapies can be made more successful if patients are treated at different times.

The results were published in the journal Nature.