According
to a study, breast cancer spreads while you're asleep
Researchers
from the University Hospital Basel, University of Basel, and ETH Zurich found
that circulating cancer cells that later develop into metastases largely appear
during the sleep phase of the affected individuals.
The
research's findings were disseminated in the journal Nature.
According
to the World Health Organization, one of the most common types of cancer is
breast cancer (WHO). Throughout 2.3 million people around the world get the
illness every year. Patients typically benefit from therapy if breast cancer is
found in its early stages by doctors.
However,
if cancer has already spread to other organs, things get much more challenging.
When circulating cancer cells split out from the primary tumour and migrate
through blood arteries to different organs, this process is known as
metastasis.
When
tumours lose metastatic cells has not received much attention in cancer
research yet. Previous research thought that tumours continuously release these
cells.
Nicola
Aceto, professor of molecular oncology, summarises the phenomenon as "the
tumour awakens when the affected person is asleep." The researchers
discovered throughout their investigation, which involved 30 female cancer patients
and mice models, that the tumour produces more circulating cells when the body
is sleeping. In addition to dividing more quickly, cells that leave the tumour
at night have a higher propensity to metastasize than circulating cells that do
so during the day.
According
to Zoi Diamantopoulou, a postdoctoral researcher at ETH Zurich and the study's
lead author, "our research demonstrates that hormones like melatonin,
which regulate our rhythms of day and night, are responsible for controlling
the escape of circulating cancer cells from the original tumour."
Modifying
treatments for the tumour
The
study also suggests that the timing of tumour or blood samples for diagnosis
may affect oncologists' conclusions. The researchers were initially pointed in
the right direction by an unintentional discovery along these lines. Aceto says
with a smile, "Some of my coworkers work early in the morning or late in
the evening; occasionally they'll even analyse blood at odd hours. The level of
circulating cancer cells in samples collected at various times of the day
varied greatly, surprising the investigators.
Another
indicator was the very large proportion of cancer cells in mice's blood
compared to that in people. The cause was that mice, which are nocturnal creatures,
slept throughout the day when investigators often collected their samples.
These
findings, according to Aceto, "may point to the need for healthcare
providers to systematically record the time at which they do biopsies."
Making the data truly comparable "may assist."
The
researchers' next task will be to determine how to best apply these discoveries
to currently used cancer therapy. ETH Professor Nicola Aceto plans to do
additional research with patients to determine whether other cancers behave similarly
to breast cancer and whether the timing of treatment for patients can improve
the effectiveness of current medications.