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. 2004 Apr 17;328(7445):921-4.
doi: 10.1136/bmj.38044.666157.63. Epub 2004 Mar 10.

Incidence of Breast Cancer in Norway and Sweden During Introduction of Nationwide Screening: Prospective Cohort Study

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Free PMC article

Incidence of Breast Cancer in Norway and Sweden During Introduction of Nationwide Screening: Prospective Cohort Study

Per-Henrik Zahl et al. BMJ. .
Free PMC article

Abstract

Objective: To determine whether any increase in the incidence of breast cancer in women detected by mammography is compensated for by a drop in the incidence after age 69, years when women are no longer invited for screening.

Design: Population based cohort study of incidence of breast cancer during the introduction of nationwide screening programmes.

Setting: Norway and Sweden.

Participants: All women aged above 30 years (1.4 and 2.9 million, respectively, in 2000).

Main outcome measures: Changes in age specific incidence rates of invasive breast cancer associated with the introduction of the screening programmes.

Results: As a result of screening the recorded incidence of breast cancer in women aged 50-69 years increased by 54% in Norway and 45% in Sweden. There was no corresponding decline in incidence after the age of 69 years.

Conclusions: Without screening one third of all invasive breast cancers in the age group 50-69 years would not have been detected in the patients' lifetime. This level of overdiagnosis is larger than previously reported.

Figures

Fig 1
Fig 1
Age specific incidence of invasive breast cancer in Norway and for age groups 30-49, 50-69, and >69 years. From 1991 incidence rate for age group 50-69 years in Norway is split between AORH counties that started organised screening in 1996 and other counties
Fig 2
Fig 2
Age specific incidence of invasive breast cancer in Sweden and for age groups 30-49, 50-69, and >69 years. Vertical line indicates start of organised screening in Sweden (1986)

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