1. Self reported stress and risk of breast cancer: prospective cohort study
Naja Rod Neilson, Zuo-Feng Zhang, Tage S Kristensen,
Bo Netterstrom, Peter Schnohr, Morten Gronbaek.
British Medical Journal
15th August 2005

2. Introduction Quantitative, longitudinal, prospective study
Objective= Relation between self reported intensity, frequency of stress, first instance of breast cancer
Women common= Hormone dependent disease, relation to high endogenous concentration

3. Introduction (cont)
Interest of breast cancer aetiology, affects hormonal system and oestrogen synthesis
Other studies with different designs
Explores impact of everyday stress, long term of first instance
Among 6,689, over 18 years,
Copenhagen City Heart study Denmark

4. Methodology Longitudinal / Quantitative data.
Age stratified random sample of 19, 689 Danish men and women.
The second examination included 7018 women: response rate 70%.
Questionnaires :
level of perceived stress
Variables considered.

5. Methodology (cont)
Second examination to the first diagnosis statistics.
Danish central death registry.
Danish national cancer registry.
Trendy analysis.
Subgroup analyses.

6. Baseline characteristics:
Results
Baseline characteristics:
Mean age was 57.
10% reported stress.
Hormone Therapy (HT) / high stress.
39.3% highly stressed.
Medium stressed were 30.4%.
251 cases during follow-up.

7. Stress intensity, Risk of cancer.
Results (cont)
Stress intensity, Risk of cancer.
7% high stress intensity.
10% high frequency of stress.
Primary breast cancer & stress.
8% reduction after adjustment.
High stress inversely associated with cancer.
Hazard ratio of 0.60.

8. Results (cont) Subgroup analysis: 114 first time PBC
137 cases in the last 9 years.
16% receiving HT were at risk.
Effect modification was P=0.09.
HR was 0.83 on women receiving HT.
No effect modification.

9. Evaluation
Population recruited from different study – results affected?
No time scale to questions.
Three options on readings – wasted responses?
What is stress?

10. Evaluation (cont) No adjustment for family history or smokers.
Smoking linked with breast cancer.
(Bennicke et al.1995 BMJ)
Suppression theory – based on animal studies.

11. Evaluation (cont)
Research backs up theory – oestrogen increases risk of breast cancer.
(Thomas et al. 1997, British Journal of Cancer)
Oestrogen only therapy – slight increased risk (Million Women Study, cited in Vickers, 2005)

12. Improvements Qualitative / Likert scale.
Continuous follow-up / smaller worldwide population.
Education on factors which influence incidence.
Mammograms

13. ANY QUESTIONS?
Presented by:
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