Advanced breast cancer incidence following population-based mammographic screening

Abstract

Background: Breast cancer mortality is declining in many Western countries. If mammography screening contributed to decreases in mortality, then decreases in advanced breast cancer incidence should also be noticeable.

Patients and methods: We assessed incidence trends of advanced breast cancer in areas where mammography screening is practiced for at least 7 years with 60% minimum participation and where population-based registration of advanced breast cancer existed. Through a systematic Medline search, we identified relevant published data for Australia, Italy, Norway, Switzerland, The Netherlands, U.K. and the U.S.A. Data from cancer registries in Northern Ireland, Scotland, the U.S.A. (Surveillance, Epidemiology and End Results (SEER), and Connecticut), and Tasmania (Australia) were available for the study. Criterion for advanced cancer was the tumour size, and if not available, spread to regional/distant sites.

Results: Age-adjusted annual percent changes (APCs) were stable or increasing in ten areas (APCs of -0.5% to 1.7%). In four areas (Firenze, the Netherlands, SEER and Connecticut) there were transient downward trends followed by increases back to pre-screening rates.

Conclusions: In areas with widespread sustained mammographic screening, trends in advanced breast cancer incidence do not support a substantial role for screening in the decrease in mortality.

Figure 1.

Age-adjusted incidence rates of advanced breast cancer in Northern Ireland, Scotland, Firenze (Italy), The Netherlands, Geneva (Switzerland), and Norway. The interrupted vertical line indicates the year of screening start. Criterion for advanced cancer is a tumour size > or ≥20 mm (dots) or non-local cancer (squares). Rates were age adjusted using the World standard population (for Northern Ireland and Scotland) and the European standard population (for The Netherlands and Geneva). No information on age-adjustment was provided for the Norway pilot project and for Firenze (Italy).

Figure 2.

Age-adjusted incidence rates of advanced breast cancer in the United States. The interrupted vertical line indicates the year of screening start (not displayed in Rhode Island where it started in 1983). The doted line is the first year of the Breast and Cervical Cancer Early Detection Program. Criterion for advanced cancer is a tumour size >20 mm (dots) or non-local cancer (squares), or (for Rhode Island) stages II–IV (squares). Rates were age adjusted using the 2000 US standard population but for New Mexico where the 1970 US standard population was used.

Figure 3.

Age-adjusted incidence rates of advanced breast cancer in Victoria and New South Wales (Australia). The interrupted vertical line indicates the year of screening start. Criterion for advanced cancer is a tumour size >15 mm in Victoria and ≥20 mm in New South Wales and Tasmania. Rates were age adjusted using the World standard population for Victoria and Tasmania and the 1991 Australia standard population for New South Wales.