Colorectal cancer mortality in two areas of Tuscany with different screening exposures

Several randomized trials have demonstrated the efficacy of colorectal cancer screening by the fecal occult blood test in reducing colorectal cancer mortality, but an evaluation of population-based screening programs is still lacking. We compared the colorectal cancer mortality rates (both adjusted rates and 3-year moving average rates) during 1985-2006 for two geographic areas in the provinces of Florence and Prato in the Tuscany region of Italy that began active population-based screening for colorectal cancer at different times: the Empolese-Mugello district, in the early 1980s, and the rest of the Florence and Prato provinces, in early 2000. A log-linear Poisson model was used to estimate the annual percent change in mortality and to examine whether geographic area modified the effect of calendar year on it. The Empolese-Mugello district had a greater decrease in colorectal cancer mortality than the rest of the Florence and Prato provinces (estimated annual percent change in age-adjusted colorectal cancer mortality rate, 2.7% decrease per year [95% confidence interval {CI} = 1.7% to 3.7%] vs 1.3% decrease per year [95% CI = 0.8% to 1.7%], respectively). The interaction between calendar period and area was statistically significant (P < .001). Our results support the hypothesis that the implementation of colorectal cancer screening in the early 1980s in the Empolese-Mugello district, where approximately 17 500 people were tested each year with the fecal occult blood test, was associated with a larger reduction in colorectal cancer mortality than that observed in the rest of Florence and Prato provinces, where screening started 15-20 years later and where approximately 38 000 people were screened each year beginning in 2000.