A discussion about stress should be a recognised part of every cancer diagnosis, an expert investigating the biological impact of "fight-or-flight" responses has claimed.
Dr Melanie Flint's research suggests that stress reduces the effectiveness of a common chemotherapy drug used to treat breast cancer.
Other cancer treatments may also be impaired by the action of stress hormones, she believes.
Diagnosis is one of the most stressful times for cancer patients as they hear the bad news about their condition for the first time.
Dr Flint, whose work at the University of Brighton has focused on breast cancer, said: "A diagnosis of breast cancer is a cause of a great deal of stress, which in itself is a significant reason for stress management to be considered early on.
"We know reducing stress improves psychological well-being, but our findings give us the idea that this elevation in stress hormones, or perhaps changes in receptors that stress hormones bind to, may affect patients' responses to chemotherapies.
"What I would like to see is that every patient diagnosed with cancer has their stress recognised and their options talked through, and an offer of stress reduction."
Many chemotherapy agents, including paclitaxel which is used to treat both breast and ovarian cancer, specifically target rapidly dividing cells.
Dr Flint's team found that breast cancer cells exposed to stress hormones such as cortisol and norepinephrine generate destructive DNA-damaging molecules called free radicals. This causes the cells temporarily to halt their relentless cell division as DNA repair mechanisms kick in.
But while halting cancer cell division may sound like good news, it actually shields the tumours from the lethal effects of paclitaxel.
Early results from the on-going studies were reported in the journal Breast Cancer Research in March.
Another finding was that stressed mice with breast cancer produced higher levels of a nitric oxide-generating enzyme, iNOS, in their tumours. Greater iNOS activity has been linked to higher grade, more aggressive breast cancer.
Dr Flint, whose work will feature at the British Science Festival taking place next week in Brighton, is now moving the research out of the laboratory to investigate the impact of stress on patients undergoing treatment.
She said it was too early to discuss the new findings but added: "We are seeing effects."
Drugs that counteract stress hormones, such as beta-blockers, may prove helpful to cancer patients as well as calming practises such as mindfulness, meditation and yoga, she pointed out.
Colleague Dr Val Jenkins, from the University of Sussex, said: "Combining the expertise of laboratory-based scientists with that of psycho-oncologists in an innovative area of research is likely to produce tangible benefits for patients receiving cancer treatments."
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