A case-control study to estimate the impact of the Icelandic population-based mammography screening program on breast cancer death.
BACKGROUND
The Icelandic breast cancer screening program, initiated November 1987 in Reykjavik and covering the whole country from December 1989, comprises biennial invitation to mammography for women aged 40-69 years old.


OBJECTIVE
To estimate the impact of mammography service screening in Iceland on deaths from breast cancer.


METHODS
Cases were deaths from breast cancer from 1990 onwards in women aged 40 and over at diagnosis, during the period November 1987 to December 31, 2002. Age- and screening-area-matched, population-based controls were women who had also been invited to screening but were alive at the time their case died.


RESULTS
Using conditional logistic regression on the data from 226 cases and 902 controls, the odds ratio for the risk of death from breast cancer in those attending at least one screen compared to those never screened was 0.59 (95% CI 0.41-0.84). After adjustment for healthy-volunteer bias and screening-opportunity bias, the odds ratio was 0.65 (95% CI 0.39-1.09).


CONCLUSIONS
These results indicate a 35-40% reduction in breast cancer deaths by attending the Icelandic breast cancer screening program. These results are consistent with the overall evidence from other observational evaluations of mammography-based programs.
Gabe
R
R
Cancer Research UK, Centre for Epidemiology, Mathematics and Statistics, Wolfson Institute of Preventive Medicine, London, UK and Icelandic Cancer Society (Krabbameinsfélag Islands), Reykjavik, Iceland. rg@ctu.mrc.ac.uk
Tryggvadóttir
L
L
Sigfússon
B F
BF
Olafsdóttir
G H
GH
Sigurdsson
K
K
Duffy
S W
SW
D000328:Adult; D000368:Aged; D015982:Bias; D001943:Breast Neoplasms / Q000401:mortality*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007055:Iceland / Q000453:epidemiology; D008327:Mammography / Q000706:statistics & numerical data*; D008403:Mass Screening / Q000706:statistics & numerical data*; D008875:Middle Aged; D009313:National Health Programs