If you were a cancer patient, wouldn’t you rather be told, “Be positive or optimistic or hopeful, it may make you feel better”, than “positive emotions won’t make a difference”?

In our research, we found that the positive emotions and moods associated with “mirthful laughter”, which is not bitter or sarcastic, has an effect on stress. Moods change as a result of laughter, helping people feel better. Further research found that you could lower the amounts of the stress hormones in the body with mirthful laughter.

Moderate exercise has the same effect as laughter, and we know that people who exercise regularly have fewer diseases. We also found that laughter increases the activity of an immune cell called natural killer (NK), which attack virally infected and tumour cells. Research has found that for breast cancer patients, better NK activity means a better prognosis.

The research looked only at head and neck cancer patients, so it is inappropriate to extrapolate the results to all other cancers. To say “the hope that we can fight cancer by influencing emotional states appears to have been misplaced”, is less than responsible. Chemotherapy is also unlikely to affect the quality of life or survival of someone with advanced cancer. Do we say that because chemotherapy doesn’t work for them it won’t work for anybody?

This study is just another piece of the puzzle, and we are still looking for the whole picture to understand the way the mind, body and immune system interact.

Dr Lee Berk is associate professor at the Schools of Public Health and Medicine at Loma Linda University, southern California

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