Cancer cells grow slower in heat

Cancer cells in mice react to ambient temperature

20/11/2013

Scientists have questioned the research results from countless cancer studies, because laboratory mice seem to be able to fight cancer more effectively at higher temperatures, unlike previously thought. As the researchers in the „Proceedings“ The US National Academy of Sciences reports that tumors develop later, grow more slowly, and produce fewer metastases when the environment is warmer. However, mice are usually kept at much cooler temperatures for laboratory testing. This finding could possibly leave the results of several studies in a different light.

Cool temperatures put mice in constant stress and make them less effective at fighting cancer cells
In principle, mice prefer an ambient temperature between 30 and 31 degrees Celsius, say the researchers to Kathleen Kokolus from the Roswell Park Cancer Institute in Buffalo, New York. In order to minimize the cleaning effort, however, mice are usually kept at room temperatures of 20 to 26 degrees. This causes the mice to change their metabolism to continue to maintain optimal body temperature. For the mice, this behavior leads to quasi-permanent stress, which could have influenced the results of earlier studies.

To determine the extent to which this effect has an impact on the fight against cancer, researchers have kept lab mice either at cooler (22 to 23 degrees Celsius) or warmer (30 to 31 degrees) temperatures. After undergoing a 14-day adjustment period, the animals injected cancer cells into the animals. It was found that at higher temperatures, the existing tumors grew much slower. In addition, significantly fewer metastases were formed.

At higher temperatures, more immune cells form to fight cancer
Further investigations revealed that more cancer-fighting immune cells (T lymphocytes) formed at higher room temperatures. At cooler temperatures, the researchers observed an opposite effect.

Finally, it has been shown that mice with cancer on their own visited areas that had an ambient temperature of about 38 degrees, write Kokolus and her team. For the future, this discovery means that in studies on the effect of a cancer drug, the influence of room temperature must be considered more. „According to our data, it is possible that our current knowledge about the ability of laboratory mice to control tumors has been compromised by the fact that the experiments were carried out under chronic cold stress, "he continues, adding that whether the findings are also used to treat people with cancer may need further investigation. (fr)