The National Cancer Institute comments on possible links between psychological stress and cancer:
Scientists know that psychological stress can affect the immune system, the body’s defense against infection and disease (including cancer).
Psychological stress refers to the emotional and physiological reactions experienced when an individual confronts a situation in which the demands go beyond their coping resources.
Recent research.. suggests that the body’s neuroendocrine response (release of hormones into the blood in response to stimulation of the nervous system) can directly alter important processes in cells that help protect against the formation of cancer, such as DNA repair and the regulation of cell growth.
Studies have indicated that stress can affect tumor growth and spread, but the precise biological mechanisms underlying these effects are not well understood. Scientists have suggested that the effects of stress on the immune system may in turn affect the growth of some tumors. However, recent research indicates that the body’s release of stress hormones can affect cancer cell functions directly
A review of studies that evaluated psychological factors and outcome in cancer patients suggests an association between certain psychological factors, such as feeling helpless or suppressing negative emotions, and the growth or spread of cancer.
Additional information about stress can be found on the National Institute of Mental Health’s (NIMH) website and The National Women’s Health Information Center (NWHIC) website, a service of the US Office on Women's Health.
The National Cancer Institute fact sheet 'Stress and Your Health' provides answers frequently asked questions about causes of stress, how women react to stress, and ways to handle stress.
Antoni MH, Lutgendorf SK, Cole SW, et al. The influence of bio-behavioural factors on tumour biology: Pathways and mechanisms. Nature Reviews Cancer 2006; 6(3):240–248.
Thaker PH, Han LY, Kamat AA, et al. Chronic stress promotes tumor growth and angiogenesis in a mouse model of ovarian carcinoma. Nature Medicine 2006; 12(8):939–944.