Effectiveness of Prevention What Is the Evidence

1
Effectiveness of Prevention What Is the
Evidence?
Should Screening for Breast Cancer Be Recommended?
World Congress of Epidemiology Pre-congress
Workshop Montreal, Canada, 18 August 2002
2
Introduction

• Christoph Trautner
• MD, MPH
• Professor of Medicine/Public Health
• University of Applied Sciences, Wolfsburg
• Germany

3
Prevention of death from breast cancerby early
detection and treatmentseems plausible and
relevant.
4
HoweverInconsistent results of randomized
controlled trials (RCTs)of mammography screening
5
(No Transcript)
6
Results vary

• between
• 25 reduction of breast cancer mortality
• due to screening (Swedish trials)
• and
• zero effect (Canadian trial)
• Validity of trials has been questioned
• (Gøtzsche and Olsen, 2000)

7
Swedish Mammography Studies   (Nyström et al.,
Lancet 2002 359 909-19)     Relative Risk of
death due to breast cancer 0.79 Out of 10.000
screened women, 39 died of breast cancer   Out
of 10.000 women of the control group (not
screened), 50 died of breast cancer
8

• Theoretically, if screening had been carried out
  in 10.000 women of the control group
• 11 lives could have been saved
•  
• 39 women would have died of breast cancer
• despite screening
•  
• 9.950 women would not have died of breast
  cancer, whether screened or not.
•  

9
If mammography screening does reduce mortality

• Sensitivity, specificity, predictive value
  positive
• False positive screening results
• Interventions, surgery .....
• Anxiety ...
• Cost effectiveness,
• compared with other preventive measures

10
Screening Scenario   Prevalence of breast
cancer in the screened population 0.6
  Sensitivity of Mammography Screening 93   Sp
ecificity of Mammography Screening 93
11
10.000
Breast Cancer
No Breast Cancer
9.940
60
9.244
56
4
696
Mammography positive negative
Mammography positive negative
12

• Predictive Value Positive 7.4
•  
• 56 out of 752 women (7.4 )
• with a positive mammogram
• have breast cancer.

13
Goals of this Symposium

• Bring together experts with different points of
  view
• Constructive, controversial debate
• Full involvement of the audience
• What do we agree on?
• What is controversial?
• What should we recommend?
• What should we do?

14
Program 1000-1030 C. Trautner Introduction  
What is the Evidence Base for Mammography
Screening? Assessing the Evidence from Randomized
Trials   1030-1100 H. de Koning The case for
mammography screening   1100-1130 (P.
Gøtzsche) The fallacy of mammography
screening   Coffee Break   1200-1230 A.
Miller Remarks about mammography screening
trials    Lunch Break    1330-1400 C.
Phillips Methodological remarks   1400-1430 Di
scussion   Coffee Break Ethical Issues,
Outlook   1500-1530 P. Vineis (presenter)
/ N. Biller-Andorno Ethical issues and
dilemmas in breast cancer prevention   1530-1630
Discussion and Closing Remarks