Decreased breast cancer tumor size, stage, and mortality in Rhode Island: an example of a well-screened population.

BACKGROUND Since the 1980s, Rhode Island has achieved one of the highest mammography screening rates in the nation. The objective of this study was to determine the effect of high mammography rates on breast cancer presentation and outcomes. METHODS Using the Rhode Island Cancer Registry, the incidence of DCIS and invasive cancer, tumor size, stage, rate of BCS and mortality from breast cancer were determined from 1987 to 2001. RESULTS Over 80% of Rhode Island women report routine mammography. From 1987 to 2001, there were 1,660 cases of DCIS and 11,301 cases of invasive breast cancer. Although the overall incidence of invasive cancer was stable, the median diameter decreased from 2 cm to 1.5 cm with a significant decrease in the incidence of stage III and IV cancers. There was an increase in BCS for women 50 to 64 years of age with stage I and II disease and for women older than 65 years with stage I disease. Disease-specific mortality decreased by 25%. CONCLUSIONS High mammography rates in Rhode Island are associated with smaller and earlier-stage breast cancers. This largely accounts for the decreased mortality from breast cancer and the increased rate of BCS.