Does Anxiety Increase Cancer Severity?

In a new study published in PloS ONE researchers concluded that anxiety-prone mice developed more severe cancer than those that were calmer. Researchers found that after doses of ultraviolet rays were applied to hairless mice, those that were more reticent and tended to avoid risks developed more tumors and invasive cancer.  Other researchers have linked chronic stress to higher risks of cancer,  but this is the first study to biologically connect the personality trait of high anxiety to greater cancer threats.

Researchers hypothesized that highly anxious mice would err on the side of avoiding danger. They placed hairless mice on a raised, cross-shaped track that had one walkway enclosed by walls and the other open. Then they measured how often each mouse ventured to the open track.  They also placed the mice in a box that was half lit and half dark and determined those that spent the most time in the dark side. After determining those that were more anxious and those that were not they exposed the mice to ultraviolet rays for 10 minute bouts three times a week for 10 weeks. They said this would be similar to humans who were overexposed to the sun. A few months later tumors appeared.

When comparing tumors in the low and high anxious mice they found higher levels of immune-suppressing cells or regulatory T cells that normally thwart overzealous responses, in the more nervous mice. The nervous mice were also making fewer of the chemical signals that start an immune attack on the tumors. Researchers also evaluated the hormone corticosterone which is excreted in response to the fight or flight response under stress and found this higher in the nervous mice.

The researchers plan to test this hypothesis in humans in the future.

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