A person’s mood may affect how well their cancer treatment works, suggests new research from China. In a report presented at the annual meeting of the European Society for Medical Oncology Asia, researchers led by Yufeng Wu, from the Affiliated Cancer Hospital of Zhengzhou University in China, found that cancer patients who were more depressed showed worse response to chemotherapy than those without depression.

Previous studies have found that people with certain mood disorders show lower blood levels of a compound called brain-derived neurotrophic factor (BDNF), which is involved in helping nerves in the brain grow and mature. (How BDNF is related to these mental illnesses is an area of active research.) Because so many people with cancer also have depression, Wu wanted to see if the BDNF levels were important in cancer. He measured BDNF levels of 186 people recently diagnosed with advanced lung cancer, who also answered questions about their mood.

Wu found that among the cancer patients with depression, those who had the lowest BDNF levels had the least response to chemotherapy for their cancer.

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It’s not yet clear whether BDNF itself is responsible for dampening chemotherapy’s effect, or if BDNF is a marker for other changes associated with depression that are interfering with chemotherapy. But the data suggest that one potential way to help people with advanced cancer improve their chances of surviving longer is to treat their depression. The next studies will have to compare people with depression and cancer who are treated with antidepressants to see if treating the depression also helps improve the treatment of their cancer.

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