Breast cancer incidence in Spain before, during and after the implementation of screening programmes.
BACKGROUND
A downturn in breast cancer (BC) incidence among Spanish women has been recently reported and attributed to screening saturation. This article analyses BC trends and their relationship with the introduction of the screening programme in all Spanish regions having available information.


METHODS
The study covers the period 1980-2004. All Spanish population-based cancer registries with 10 years of uninterrupted registration furnished data on invasive BC. Trends in BC incidence among women aged <45 years and among those aged > or =45 years were assessed using Poisson transition models to estimate the existence of a change-point in the overall trend. Furthermore, in those regions that had registered BC incidence before implementing the screening programme, the annual percentage change in women aged > or =45 years was computed before screening, during the first round of screening and after full coverage had been achieved.


RESULTS
The study included 82 699 incident cases. Whereas BC increased during the 1980s and 1990s, from 2001 onwards a decline was observed among women aged > or =45 years. This phenomenon was clearly visible in regions that had implemented BC screening before 2000 and attained high participation rates. In such areas, BC incidence rose sharply during screening implementation, with an overall increase of approximately 20%-30%. BC incidence fell once full coverage was achieved and tended to level off or even increase thereafter, as was the case in Navarre. In women aged <45 years, BC increased by 1.7% per annum across the period.


CONCLUSIONS
Screening has strongly influenced recent BC trends among Spanish women aged > or =45 years. Our results support the influence of screening saturation on the recent decline of BC. Among younger women, incidence is still rising, probably reflecting the lifestyle changes observed in younger generations.
Pollán
M
M
Cancer and Environmental Epidemiology Unit, National Centre for Epidemiology, Carlos III Institute of Health, Madrid, Spain. mpollan@isciii.es
Michelena
M J
MJ
Ardanaz
E
E
Izquierdo
A
A
Sánchez-Pérez
M J
MJ
Torrella
A
A
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000453:epidemiology* / Q000517:prevention & control; D055088:Early Detection of Cancer / Q000379:methods* / Q000639:trends*; D005260:Female; D006284:Health Plan Implementation / Q000379:methods / Q000639:trends; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D013030:Spain / Q000453:epidemiology; D013997:Time Factors