Invasive breast cancer incidence among women 50 years old or older by tumor size, race/ethnicity, and year according to Surveillance, Epidemiology, and End Results-13. (a) Trends for tumors with diameter less than 2 cm. (b) Trends for tumors with diameter greater than or equal to 2 cm. (c) Trends for unknown tumors. All rates are age-adjusted to the 2000 US standard.