By Richard Frank, MD
One of the most common and difficult-to-answer questions I receive from my patients is, “Does stress cause cancer?” Many individuals can report very stressful experiences occurring prior to the time of a cancer diagnosis or relapse. Many feel that somehow stress played a role in their illness. Is there any evidence for this? I will try to provide some insight, if not conclusive evidence on this topic.
One of the dictionary definitions of stress is, “A condition of metabolic or physiologic impairment in an organism, occurring usually in response to adverse events and capable of causing physical damage.” As it relates to psychological stress, some have defined it as ‘occurring when events exceed an individual’s perceived ability to cope.’ However it is defined, we all know what stress is and there is no such thing as a stress-free life. There can be acute or sudden stressors such as an injury, loss of a loved one, or a cancer diagnosis; and chronic stressors, such as caring for a spouse with Alzheimer’s disease, job strain, or unemployment. An acute stress can lead to chronic stress and both types of stress can lead to depression or other types of mental illness. Studying the effect of life events on illness can clearly become quite challenging.
Epidemiological studies have linked stress, depression, and lack of social support to the development of cancer. For example, in a large Finnish study, divorce, loss of a husband, and loss of a close friend were all associated with an increased risk of breast cancer. On the other hand, several studies have found associations between a strong social support network and improved outcomes in cancer patients. An emerging field of research has been demonstrating the beneficial effects of yoga, mindfulness meditation, and other methods of relaxation on improving the wellbeing and outcomes of those fighting cancer. How are these effects mediated?
There is a field of science called “psychoneuroimmunology” (PNI) that deals with trying to link our mental/emotional states of relaxation or stress, depression, and other disturbances with their effects on our endocrine and nervous systems as well as the immune system. These biological changes are then correlated with effects on health and disease. For example, stress causes the central nervous system to release the “flight or fight” chemicals epinephrine and norepinephrine , as well as cortisol, prolactin, and growth hormone. These hormones can alter the numbers and types of immune cells, such as T-cells and natural killer (NK) cells produced by the body and also increase inflammation. Since immunity and inflammation affect cancer, stress is extrapolated to affect cancer on this basis. But a firm scientific basis for the effect of stress on cancer has still not been established.
Regardless of exactly why stress may influence the development and progression of cancer, the good news is that we are learning how to counteract this effect. All the forms of integrative medicine that have become popular among cancer patients — acupuncture, yoga, tai chi, reflexology, massage, reiki, Quigong, music therapy, and others can be thought of as additional ways to fight cancer. Since social support is so important, I will also add that support groups and counseling are also therapeutic in the fight against cancer. By lowering stress and coping more effectively, a cancer patient may actually be improving their chances of survival.