There is much speculation about the role of stress in causing cancer. Many therapies aimed at relieving stress have been advocated as treatments for cancer. There is a complex relationship between psychological states and physical wellbeing. Stress may be able to change the immune system and hormone levels. It has been difficult, though, to establish stress as a cause of cancer, independent of other causes. A reason for this may be illustrated by simply stating that increased stress may be associated with increased smoking, overeating or becoming ‘run down’, all of which may impact on the development of cancer.
Intuitively, we may question the strength of the association between stress and cancer because we all know people who lead high-stress lives and don’t develop cancer, arid layabouts who do. I also have a problem with doctors who tell patients that their stressful lifestyle caused their cancer. This adds to the burden that patients must bear since they blame themselves for developing cancer, when it is not the case. Stress can be a nice intangible explanation but adds to the burden of the diagnosis.
Intuition is not very scientific, so what do the studies show? Well, for a start, it has proved difficult to define stress, since the concept varies between individuals. What many of the studies have done is to look at social stress factors, such as the death of a loved one or examinations. Several studies have suggested an increased death rate in people who have recently lost a relative. This includes cancer deaths, but a recent bereavement can’t have been the cause of the cancer since, as we have seen, the cancer probably started developing years before.
Many studies have focused on breast cancer risk. One large National Cancer Institute study in the United States showed no association between stressful life events and the risk of breast cancer. Other studies, however, have linked stressful life events to the recurrence of breast cancer and yet others have suggested an increased incidence of breast cancer in highly stressed individuals.
Spiegel has claimed that regular psychological support improves survival in cancer patients. We await other studies to see if the improvement in survival was due to the psychological support or related to other factors, such as other treatments used. Certainly, Greer and others have reported that patients who respond to the diagnosis of cancer with a fighting spirit do better than more passive individuals.
Much more needs to be learned about psychological factors in the aetiology of cancer but, until we have such facts, definite statements about the relationship between stress and cancer should not be made.