As temperatures start to cool off after a warm stretch, it can come as a bit of a relief to many of us. A new study finds such conditions may also mobilize body processes that help slow tumor growth.
Researchers from Karolinska Institutet in Sweden recently examined how tumors responded to different temperatures. In mice and in a cancer patient, the team found that cool temperatures activated brown fat that warms the body by consuming sugar. That limited the amount of sugar available to tumors, which need it to grow. The findings, published in the journal Nature, could give new insights into cancer treatment.
Yihai Cao, co-author and professor in the Department of Microbiology, Tumor and Cell Biology at the school, says, “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.”
The team tested the impacts of temperature on mice with several types of cancer, including breast cancer. They found that those acclimated to 39 degrees Fahrenheit exhibited slower tumor growth and lived almost twice as long as those in 86 degree rooms. Upon further study of tissue markers and glucose metabolism, they learned that the cold temperatures led brown fat to consume large amounts of glucose to keep the body warm. While this occurred, the tumor cells had barely detectable glucose signals.
To understand how much the brown fat was contributing, the team removed either it or a key protein related to its metabolism, UCP1. This appeared to eliminate the benefits of the cold temperatures, as tumors resumed a growth rate comparable to that of the hot temperature group. Upping the mice’s glucose levels through a sugary drink had the same effect. The team says this suggests that limiting glucose supply is important in keeping tumor growth in check.
To see if these findings could be replicated in humans, the researchers examined temperature impacts on six healthy people and a cancer patient undergoing chemotherapy. The healthy participants spent up to six hours a day in 61 degree temperatures for two weeks, wearing shorts and T-shirts. PET scans showed that there was significant brown fat activation in their necks, spines, and chests.
The patient, meanwhile, wore light clothing in 72 degree temperature rooms for a week, followed by four days in 82 degree temperature rooms. PET scans showed higher brown fat glucose intake and lower tumor glucose intake in the lower temperatures. The team hopes this could be a less invasive way to help improve cancer treatments.
Cao says, “These temperatures are considered tolerable by most people. We are therefore optimistic that cold therapy and activation of brown adipose tissue with other approaches such as drugs could represent another tool in the toolbox for treating cancer.”
This isn’t the only way that temperature can be used against cancer. Another option, typically used in conjunction with other treatments, is called hyperthermia treatment. This method heats up body tissue to as high as 113 degrees to help damage and kill cancer cells. According to the National Cancer Institute, clinical trials have shown that it’s an effective complement to radiation or chemotherapy.