A case-control study of breast cancer risk in nurses from Northeastern Ontario, Canada.

ABSTRACT

PURPOSE: Previously published findings have documented increased breast cancer risks associated with the nursing profession. The aim of the present study was to assess whether an increased risk of breast cancer was associated with nursing in a population-based case-control breast cancer study of women in Northeastern Ontario, Canada. METHODS: A total of 1519 women (1380 never-nurses 716 controls and 664 cases; 139 ever-nurses 59 controls and 80 cases) were included in the present study. Study participants filled out a detailed questionnaire which included a history of smoking, general health information, breast cancer risk factors, and a detailed occupational history. RESULTS: Ever-nurses were at higher, but nonsignificant risk of breast cancer compared to never-nurses (adjusted OR 1.39, 95 % CI 0.93-2.07). Ever-nurses who worked for longer than 10 years were at a significantly increased risk of breast cancer compared to never-nurses (adjusted OR 1.70, 95 % CI 1.04-2.79). A nonsignificant, but increased risk of breast cancer was observed in ever-nurses who worked full-time compared to never-nurses (OR 1.52, 95 % CI 0.92-2.52), while nurses who worked part-time, or both part-time and full-time were not at increased risk. Ever-nurses who worked in a hospital setting had a significantly increased risk of breast cancer (OR 1.65, 95 % CI 1.04-2.62) compared to never-nurses. CONCLUSIONS: The results indicate that the nurses in the present study population are at increased risk of breast cancer. A prolonged duration of nursing years and prolonged intensity (being a full-time nurse) are factors associated with this increased risk.