Rate of over-diagnosis of breast cancer 15 years after end of Malmö mammographic screening trial: follow-up study.
OBJECTIVE
To evaluate the rate of over-diagnosis of breast cancer 15 years after the end of the Malmö mammographic screening trial.


METHODS
Follow-up study.


METHODS
Malmö, Sweden.


METHODS
42 283 women aged 45-69 years at randomisation.


METHODS
Screening for breast cancer with mammography or not (controls). Screening was offered at the end of the randomisation design to both groups aged 45-54 at randomisation but not to groups aged 55-69 at randomisation.


METHODS
Rate of over-diagnosis of breast cancer (in situ and invasive), calculated as incidence in the invited and control groups, during period of randomised design (period 1), during period after randomised design ended (period 2), and at end of follow-up.


RESULTS
In women aged 55-69 years at randomisation the relative rates of over-diagnosis of breast cancer (95% confidence intervals) were 1.32 (1.14 to 1.53) for period 1, 0.92 (0.79 to 1.06) for period 2, and 1.10 (0.99 to 1.22) at the end of follow-up.


CONCLUSIONS
Conclusions on over-diagnosis of breast cancer in the Malmö mammographic screening trial can be drawn mainly for women aged 55-69 years at randomisation whose control groups were never screened. Fifteen years after the trial ended the rate of over-diagnosis of breast cancer was 10% in this age group.
Zackrisson
Sophia
S
Department of Clinical Sciences in Malmö, Epidemiological Research Group, Lund University, Malmö University Hospital, SE-205 02, Malmö, Sweden. sophia.zackrisson@med.lu.se
Andersson
Ingvar
I
Janzon
Lars
L
Manjer
Jonas
J
Garne
Jens Peter
JP
D000367:Age Factors; D000368:Aged; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology; D003951:Diagnostic Errors / Q000706:statistics & numerical data*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008327:Mammography / Q000592:standards*; D008403:Mass Screening / Q000592:standards*; D008875:Middle Aged; D013548:Sweden / Q000453:epidemiology