title: A case-control study of breast cancer risk in nurses from Northeastern Ontario, Canada.
abstract: OBJECTIVE
  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.
authors.affiliation: Epidemiology, Outcomes and Evaluation Research, Northeast Cancer Centre, Health Sciences North, Sudbury, ON, P3E 5J1, Canada. ssanti@hsnsudbury.ca.
authors.forename: Stacey A
authors.initials: SA
authors.lastname: Santi
authors.affiliation: Epidemiology, Outcomes and Evaluation Research, Northeast Cancer Centre, Health Sciences North, Sudbury, ON, P3E 5J1, Canada.
authors.forename: Margaret L
authors.initials: ML
authors.lastname: Meigs
authors.affiliation: Epidemiology, Outcomes and Evaluation Research, Northeast Cancer Centre, Health Sciences North, Sudbury, ON, P3E 5J1, Canada.
authors.forename: Yantao
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Epidemiology, Outcomes and Evaluation Research, Northeast Cancer Centre, Health Sciences North, Sudbury, ON, P3E 5J1, Canada.
authors.forename: Mary A
authors.initials: MA
authors.lastname: Bewick
authors.affiliation: Advanced Medical Research Institute of Canada, Sudbury, ON, P3E 5J1, Canada.|Northern Ontario School of Medicine, Sudbury, ON, P3E 2C6, Canada.|Laurentian University, Sudbury, ON, P3E 2C6, Canada.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Lafrenie
authors.affiliation: Epidemiology, Outcomes and Evaluation Research, Northeast Cancer Centre, Health Sciences North, Sudbury, ON, P3E 5J1, Canada. mconlon@hsnsudbury.ca.|Advanced Medical Research Institute of Canada, Sudbury, ON, P3E 5J1, Canada. mconlon@hsnsudbury.ca.|Laurentian University, Sudbury, ON, P3E 2C6, Canada. mconlon@hsnsudbury.ca.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Conlon
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000453:epidemiology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008875:Middle Aged; D009726:Nurses; D009864:Ontario; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects; D011795:Surveys and Questionnaires
keywords: Breast cancer; Case–control study; Nurses/nursing