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Manual of Articles Sections 15 - 32
Cancer does not come from thoughts or feelings, but psychosocial treatment can help cancer patients.
Emotions and cancer rates
The influence of acute or chronic emotional stress is also doubtful. Danish researchers found that the death of a husband had no effect on the rate of breast cancer in women during the next 15 years. A study of all firefighters over age 43 in Stockholm, Sweden, found that they had the same rate of cancer as the general population, despite the strain of their occupation. Schizophrenic patients, although they are under severe stress and often depressed, have only an average rate of cancer.
It is important to adjust for the effects of smoking. Because people with a history of depression are more likely to smoke cigarettes -- and less likely to quit once they start (see Harvard Mental Health Letter, August 2002) -- they are at higher-than-average risk for any of the cancers associated with tobacco. Of all the disorders listed in the American Psychiatric Association's diagnostic manual, the only ones that directly increase the risk for cancer are nicotine dependence and alcohol dependence.
After the diagnosis
But a recent study of more than 200 women with breast cancer found no evidence that stress in the year before or five years after the diagnosis affected the rate of recurrence. A meta-analysis of 26 studies on fighting spirit, helplessness, hopelessness, denial, and fatalism among cancer patients found these attributes had no effect on survival or recurrence.
Another meta-analysis including 58 studies found that, on average, cancer patients are only slightly more depressed and anxious than healthy people. Their suicide rate is lower than average. Psychological symptoms are often most serious soon after the diagnosis and improve with time even if physical health worsens. Recent studies have found fewer psychiatric symptoms in cancer patients, possibly because they are getting the benefit of less stigma, earlier diagnosis, and better understanding and treatment.
Interpreting these findings is a problem, because controlled experiments may be impossible and causes are difficult to distinguish from effects. People may be more depressed, anxious, or distressed because the illness is more serious, and they may die sooner for the same reason. Symptoms of depression, cancer, and treatment side effects -- loss of appetite, insomnia, and fatigue -- can be confused. It is important not to exaggerate the influence of attitudes and emotions on the outcome of cancer. If people are led to think they can be cured by cultivating the right feelings, they may also blame themselves if they do not recover quickly.
Paths of influence
This path of influence runs through the hypothalamic-pituitary-adrenal (HPA) axis, which coordinates the body's response to life-threatening emergencies. Depression or chronic stress may cause long-term overexposure to the adrenal hormones epinephrine (adrenaline) and cortisol. Cancer and cancer treatment can make this situation worse. More than 10% of bone marrow transplant patients, according to one study, have post-traumatic stress disorder, and many others have some of the symptoms. Another study found that women with advanced breast cancer died a year sooner if they had shown abnormal daily patterns in cortisol secretion. And in still another study, women with early breast cancer who underwent group therapy had lower cortisol levels than those put on a waiting list.
An overactive HPA axis producing high levels of cortisol tends to depress the immune system. How much difference that makes to cancer patients is unclear. It could mean delayed healing of wounds after surgery. Loss of immune function could also promote the growth of tumors. In experiments on rats with an implanted tumor, repeated electrical shocks reduced the activity of natural killer cells, which are particularly important for the defense against tumors. Overcrowding and bullying by dominant rats in a colony also hasten the growth of implanted tumors in subordinate animals. According to some research, natural killer cell activity is higher in breast cancer and melanoma patients who participate in group psychotherapy.
Experiments have shown that immune reactions can be learned by association. Rats were given water containing saccharin along with a drug that suppresses the immune system. After the drug was removed, they responded to sweetened water by developing an unusually high rate of infections. By association with the immunosuppressive drug, a sweet taste provoked a conditioned response that depressed immune function. The same process may be at work when patients who have undergone repeated chemotherapy show lower immune activity before their next session.
Skeptics say this research is inconclusive because the effects are small, the studies are not always carefully controlled, and the measures of stress and immune activity are unreliable or partial. In a healthy person, emotion rarely has a dramatic effect on the immune system. A meta-analysis of 59 studies showed that stress management, relaxation techniques, and hypnosis have little effect on the immune system in a variety of illnesses. Still, even a small effect might tip the balance for some seriously ill patients, including those with cancer or undergoing chemotherapy. The National Cancer Institute is sponsoring a project that will evaluate the role of psychoneuroimmunology - the discipline that studies the relationship between the mind and the immune system -- in the understanding and treatment of cancer.
- Cancer and the Mind. Harvard Mental Health Letter. Jul 2003. Vol. 20 Issue 1.
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