Psychosocial factors such as personality traits and depression may alter immune and endocrine function, with possible effects on cancer incidence and survival. Although these factors have been extensively studied as risk and prognostic factors for cancer, the associations remain unclear. The author used data from prospective cohort studies in population-based and clinical databases to investigate these relations. The findings do not support the hypotheses that personality traits and depression are direct risk factors for cancer and cancer survival.
Some researchers have recently reported that cancer affects the psychological status of the partners and family members of cancer patients. The mechanisms underlying this hypothesis imply the existence of not only psychological distress from caregiving and grief but also a shared unhealthy lifestyle. Only a few studies have suggested that major psychosocial problems develop in partners of cancer patients. The present study used nationwide population-based data to investigate depression risk among male partners of women with breast cancer. The results support the hypothesis that such men are at increased risk of depression.
In conclusion, the effects of personality traits and depression on cancer risk and survival appear to be extremely small. In addition, partners of cancer patients were at increased risk of depression. Screening partners and family members of cancer patients for depressive symptoms is therefore an important concern for research in psycho-oncology.