English summary: ORGANISED SCREENING REDUCES MORTALITY FROMBREAST CANCER INFINLAND

Background

Mammography screening in Finland was started in 1987 using a group-randomised design. Since 1992, all 50-59-year-old Finnish women have been invited to service screening every two years. Invitations for women aged 60-69 years have been optional. In this study, the effectiveness of organised screening was evaluated from 1992 to 2003.

Methods

Incidence-based breast cancer deaths among invitees and participants at centres of the Cancer Society of Finland (n=361 848) aged 50-69 at death were compared with modelled, expected breast cancer deaths without screening. At ages 50-69, observed and expected breast cancer deaths among all women were compared in three invitational policies.

Results

The overall reduction in breast cancer mortality among the invitees aged 50-69 at death was 22% (relative risk 0.78, 95% confidence interval 0.70-0.87). The corresponding reduction among the participants was 28%. Among all women aged 50-79 at death, the greatest reduction in breast cancer mortality was estimated in municipalities that invited 50-69-year-old women on a regular basis.

Conclusion

The Finnish mammography programme has been as effective as in other European countries. Gradual expansion of invitations to women aged 50-69 in the forthcoming years will decrease breast cancer mortality among the elderly, although the annual number of prevented deaths will remain rather small, at least during the first years. Increased diagnostic and therapeutic activities outside screening, and reduction in breast cancer mortality among women less than 50 years of age provide challenges for future screening evaluation.