The role of depression in the development of breast cancer: analysis of registry data from a single institute.

Although controversial, the belief that developing breast cancer may be associated with psychological distress is not uncommon. The present study examined the role of psychological variables in the development of breast cancer in women attending a breast clinic for medical examination in Tehran, Iran. During a three-year period (1997-1999) a trained female nurse interviewed all women attending the Iranian Center for Breast Cancer (ICBC) before a confirmed diagnosis was made (N = 3000). Data were collected on demographic variables (age, education and marital status), known risk factors (age at menarche, age at first time full term pregnancy, family history of breast cancer, menopausal status, and oral contraceptive use), psychological variables, including history of psychiatric medications, depression (depressed mood, hopelessness, and loss of interests and pleasures), anxiety (mental and somatic signs) and two single measures of overall health and quality of life. In all, 243 patients were diagnosed as having breast cancer. A total of 486 patients with benign disease were randomly selected from the original cohort as controls. Univariate and multivariate logistic regression analyses were performed to determine the predictive effect of each factor on the risk of breast cancer. There were no significant differences between cases and controls except for age at menarche (P = 0.007) and family history of breast cancer (P<0.001). With regard to psychological variables studied, the results showed that there were significant differences between cases and controls regarding depression (depressed mood P<0.0001, hopelessness P = 0.001, and loss of interest and pleasures P = 0.001), and anxiety (mental signs P = 0.006). Finally, after performing multiple logistic regression analysis in addition to family history and age at menarche, depressed mood and hopelessness showed significant results (odds ratios of 1.90, and 1.63 respectively). The findings of the present study suggest that in addition to the known risk factors, psychological determinants such as depressed mood may play an important role in etiology of breast cancer and deserve further investigation, especially in different populations.