Small-area incidence trends in breast cancer.
BACKGROUND
During the past 2 decades, the observed incidence of in situ and early-stage invasive breast cancer has increased substantially as a result of increased use of mammography. Geographic variability in the increase in breast cancer incidence has been observed among large areas. Examining the variability among small areas in the incidence over time will facilitate appropriate geographic allocation of resources aimed at increasing screening.


METHODS
We examined county-specific increases in breast cancer incidence over time, specifically the variability and spatial correlation in the increase in breast cancer incidence. The analyses were based on county-level data (1973-1997) from the Iowa Surveillance, Epidemiology, and End Results program. A spatiotemporal hierarchical Bayesian model was used to examine variability in county-specific rates (intercepts, slopes, and spatial correlations) among white women at least 40 years of age.


RESULTS
Posterior values indicate there was little variability among counties in the change in breast cancer incidence over time (slope) but substantial variation among intercepts. There was considerable spatial correlation among the county-specific intercepts but a lack of a spatial correlation among the county-specific slopes. There was no correlation between the county-specific intercept and slope.


CONCLUSIONS
Breast cancer incidence increased over time, but county-specific rates increased independently relative to their neighboring counties or their initial rate.
Schootman
Mario
M
Departments of Pediatrics and Medicine, and The Alvin J Siteman Cancer Center, Barnes-Jewish Hospital and Washington University School of Medicine, St Louis, Missouri 63108, USA. mschootm@im.wustl.edu
Sun
Dongchu
D
D000328:Adult; D017677:Age Distribution; D000368:Aged; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D007484:Iowa / Q000453:epidemiology; D008403:Mass Screening; D008875:Middle Aged; D008962:Models, Theoretical; D009010:Monte Carlo Method; D011159:Population Surveillance; D012042:Registries; D018570:Risk Assessment; D012424:Rural Population; D018426:SEER Program; D012680:Sensitivity and Specificity; D016019:Survival Analysis