Cancer and depression.

Half of all cancer patients have a psychiatric disorder, usually an adjustment disorder with depression. Anxiety about illness, such as cancer, often leads to delay in diagnosis, which has been estimated to reduce prospects of long-term cancer survival by 10% to 20%. Although earlier studies showed that depressed individuals were at higher risk for cancer incidence, later studies have not confirmed this predictive relationship. Nonetheless, effective psychotherapeutic treatment for depression has been found to affect the course of cancer. Psychotherapy for medically ill patients results in reduced anxiety and depression, and often pain reduction. In three randomised studies, psychotherapy resulted in longer survival time for patients with breast cancer (18 months), lymphoma, and malignant melanoma. The physiological mechanisms for these findings have not yet been determined, but four fundamental possibilities for psychotherapeutic effects on physiological change include health maintenance behaviour, health-care utilisation, endocrine environment, and immune function. Thus, effective treatment of depression in cancer patients results in better patient adjustment, reduced symptoms, reduced cost of care, and may influence disease course. The treatment of depression in these patients may be considered a part of medical as well as psychiatric treatment.