The deficit in incidence in the previously screened age group is expected to balance out the excess in incidence in the screening ages.
This extension phase lasted until 2001; the deficit in incidence among women aged 75 years or older was expected to be observed between 2003 and 2005.
Also, it should be noted that a deficit in incidence above the age limits for screening can only occur in cohorts that have actually been through the screening programme.
However, even during the steady-state phase, overdiagnosis may further drop by a factor of 1.7 (Table 3, estimator 1, 2003 vs. 2006) as the number of women contributing to the deficit in incidence still increases.
In 1993, the modeled excess in breast cancers peaked (17.1% of all predicted cancers in women aged 50 69 years), while the modeled deficit in incidence among women no longer screened was 0.8% of all predicted cancers in that age group.
Such an effect could lead to temporal deficits in incidence and thus the occurrence of temporal clustering.
After correcting for mortality, an incidence deficit was observed (Standardized Incidence Ratio (SIR) 79; 95% Confidence Interval (CI) 39 120).
The deficit in the incidence rate almost disappeared in the year the screening program was extended to include women aged 70 74 years.
Similar estimations could be made for the burden of exposure to chemicals that decrease THs and result in IQ deficits or increased incidence of cardiovascular disease.
Indeed, from 1994 onward, a deficit in breast cancer incidence was observed.
