Depression and the lower risk for breast cancer development in middle-aged women:: a prospective study

Background. Depression has been hypothesized to be potentially linked to an increased risk of breast cancer. Few studies have addressed this question using population-based cohorts and prospective designs, adjusting for known biomedical risk factors. This has been done in the present investigation. Method. Participants were 5191 women from a cohort of women born between 1941 and 1947 and living in the city of Eindhoven, The Netherlands. All women completed questionnaires regarding the presence of depressive symptoms (Edinburgh Depression Scale) and background (demographic, medical and lifestyle) variables. The questionnaire data were linked with the records of the Eindhoven Cancer Registry. These records provided data on breast cancer diagnoses, which took place up to 5 years after the questionnaire screening. Results. Fifty-eight women (1.1%) were found to have developed breast cancer at least 2 years after the questionnaire screening. After controlling for 15 potential risk factors, of which family history of breast cancer, hypothyroidism and unilateral oophorectomy were significant predictors of breast cancer development, women with depressive symptoms had a lower risk of subsequent breast cancer (OR = 0.29, 95% Cl = 0.09-0.92, P = 0.04). Conclusions. Depressive complaints may be associated with a protective factor involved in the development of breast cancer. Some of the possible candidates for this factor are discussed.