Turning down the thermostat seems to make it harder for cancer cells to grow, according to a study in mice by researchers at Karolinska Institutet.
Prior research has shown that 28 degrees Celsius is generally considered a comfortable environmental temperature for most inactive humans. However, the new study published in the journal Nature, proved that cool temperatures are better for cancer patients as chilly temperatures activate heat-producing brown fat that consumes the sugars the tumors need to thrive.
“We found that cold-activated brown adipose tissue competes against tumors for glucose and can help inhibit tumor growth in mice. Our findings suggest that cold exposure could be a promising novel approach to cancer therapy, although this needs to be validated in larger clinical studies,” says Professor Yihai Cao at the Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, and corresponding author.
The study compared tumor growth and survival rates in mice with various types of cancer, including colorectal, breast and pancreatic cancers, when exposed to cold versus warm living conditions. Mice acclimatized to temperatures of 4 degrees Celsius had significantly slower tumor growth and lived nearly twice as long compared with mice in rooms of 30 degrees Celsius.
To find out why that is, the researchers analyzed markers in the tissue to study cellular reactions and used imaging tests to examine glucose metabolism. Cancer cells typically need large amounts of glucose, or sugar, to grow.
“Interestingly, high sugar drinks seem to cancel out the effect of cold temperatures on cancer cells, suggesting that limiting glucose supply is probably one of the most important methods for tumor suppression,” Yihai Cao says.
To study the human relevance of the findings, the researchers recruited six healthy volunteers and one patient with cancer undergoing chemotherapy. Using positron emission tomography (PET) scanning, the researchers identified a significant amount of brown fat activated in the neck, spine and chest area of healthy adults wearing shorts and T-shirts while being exposed to a slightly chilly room temperature.