Immunity and Psychosocial Factors as Cancer Risks in a Middle Aged Population(Symposium : Frontiers Research and Practice in Psychosomatic Medicine)

Abstract

Increased cancer risks are associated with immune suppression and psychosocial factors such as depressive symptoms. Reduced NK cell activity is correlated with psychosocial stresses in cross sectional studies and with increased cancer risks in prospective cohort studies. We have conducted a prospective cohort study in middle aged individuals to elucidate relationships between cancer, immune function and psychosocial factors. Data were obtained from a cohort of 3790 workers, aged 18 to 60 years, beginning in April 1997. At baseline, we measured lymphocyte subpopulations for all participants, and assayed cytokines and NK cytotoxicity for 247 participants. During a 7-year follow-up of this cohort, we identified new cancer cases and attempted to correlate cancer with immune system and psychosocial parameters. After controlling for sex, age, cigarette smoking, alcohol consumption, marital status, education, body mass index (BMI), physical activity and family history of cancer, the hazard ratio of cancer incidence, relative to the number of memory CD4 + CD45RO+T subpopulations were around 8.0. We have also shown that depressive symptoms increased cancer risk via reduced NK cell activity and Th2 shift (adjusted HR=2.67) and that low self esteem increased cancer risk via reduced NK cell activity (adjusted HR=2.22). Increased cancer risks were found in subjects with reduced immune system function, depressive symptoms and low self esteem. I also reviewed the literatures on the relationship between stress and cancer incidence in this article.