Trends in breast cancer mortality, incidence, and survival, and mammographic screening in Tuscany, Italy

Objective: The study describes breast cancer mortality trends in Tuscany (p eriod 1970-97), comparing Florence with the rest of Tuscany (Florence exclu ded), and, for Florence, incidence (period 1985-94) and survival (1985-86 v ersus 1991-92) trends, taking into account the diffusion of screening. Methods: Mortality and incidence rates, age-adjusted on the European popula tion, and 95% confidence intervals (95% CI). Five-year relative survival ra tes and estimates of risk of dying provided by the Cox model. Results: Mammographic screening, started at the beginning of the 1970s in s ome municipalities, largely involved the Florence area after 1990 (mammogra ms/years: from 8000-9000 to 28,000-29,000, respectively, before and after 1 990). In the same period no population-based screenings were ongoing in the rest of Tuscany. A significant mortality drop was observed in Tuscany (-3. 7%/year), starting at the beginning of the 1990s and observed for ages less than or equal to 74 (especially ages 40-49: -11.2%/year). The drop was sim ilar in Florence and in the rest of Tuscany. In ages 50-69, incidence, incr easing between 1985-87 and 1988-90 (+6.5%), rose sharply in 1991-94 (+17.0% ); it was stable in other ages. Local disease increased more markedly in ag es 50-69 (globally: +88.3%), but also in other ages (+20-30%). Regional and metastatic cancers decreased. A significantly better 5-year survival was o bserved among cases diagnosed in 1991-92, persisting after adjustment by ex tent of disease. Conclusion: Even if the causes of breast cancer mortality trends are not ea sy to clarify in an observational study, our data suggest that the drop in mortality observed in Tuscany at the beginning of the 1990s could be largel y explained by both earlier detection, outside of an organized screening pr ogram, and by better treatments. The increase in incidence and the shift in stage distribution that occurred before the enlargement of the screening a rea and in age groups not involved in the program, supports the role of a ` spontaneous' widespread earlier detection. The better survival of the perio d 1991-92, only partly explained by the shift in stage at diagnosis, indire ctly supports the role of improvement in therapy.