Population-based estimate of the prevalence of HER-2 positive breast cancer tumors for early stage patients in the US.

The goal of this study was to estimate prevalence of HER-2 positive tumors in a population-based sample of 1026 women diagnosed in 2005 with early stage breast cancer. We modeled the relationship between patient and tumor characteristics and HER-2. HER-2 positive estimates were 19% for women aged ≤ 49 years and 15% aged ≥ 50 years. HER-2 varied by tumor grade and size in women aged ≤ 49 years but was not significant in multivariate analysis. Tumor grade and race were associated with HER-2 for women aged ≥ 50 years after controlling for other variables. HER-2 varies by age and by race and tumor in older women.