Risk-adjusted female breast cancer incidence rates in the United States

Abstract

A method has been previously proposed for estimating risk-adjusted incidence rates (RAIRs) from cancer data from the Surveillance, Epidemiology, and End Results (SEER) program. Unlike conventionally reported SEER-based cancer incidence rates in the United States, but similar to the approach taken by the International Association of Cancer Registries and the International Agency for Research on Cancer, the method uses only the first primary cancer of the given site. In addition, it also adjusts for population-based cancer prevalence in order to obtain a better population-based measure of cancer risk. For most cancers multiple cancer primaries are rare and the prevalence of the disease is low. However, female breast cancer has a comparatively high risk of subsequent breast cancers and is the most prevalent cancer in women. Hence, in white women RAIRs are 3.0% lower in ages 30–39, 4.2% lower in ages 40–49, 4.0% lower in ages 50–59, 4.1% lower in ages 60–69, 3.8% lower in ages 70–79, and 4.3% lower in ages 80 years and older compared with conventional rates. Corresponding lower percentages for black women are 3.9%, 6.9%, 5.1%, 7.8%, 6.0%, and 2.2%, respectively. Age-group specific trends in breast cancer incidence rates differed between RAIRs and conventional incidence rates, increasingly so with older age. The number of cancer cases in the United States is estimated from conventional incidence rates and population estimates. In 2007, the estimated number of malignant breast cancer cases was 181,665 for white women and 20,203 for black women. The estimated number of breast cancer cases decreased by 4.8% for whites and 6.5% for blacks when based on RAIRs. RAIRs are a better measure of breast cancer risk and trends in RAIRs are better for monitoring the effect of risk factors.