Ductal carcinoma in situ of the breast, a population-based study of epidemiology and pathology

In a population-based series of 2109 women with ductal carcinoma in situ (DCIS) diagnosed in 1995-2000 in New South Wales, Australia, incidence increased by an average of 5.5% a year, mostly between 1995 and 1996 and in women 50-69 years of age. This increase paralleled the increases in mammographic screening. BreastScreen NSW, an organised mammographic screening programme, detected 65% of all DCIS. High-grade lesions were 54% of all lesions and were more likely to be 2+ cm in diameter (OR=2.12, 95%CI 1.46-3.14) than low-grade lesions. In all, 40% of DCIS in women younger than 40 years was 2+ cm in diameter compared with 21% in women 40 years and older. Young age, high grade, mixed architecture and multifocality were significant and independent predictors of 2+ cm DCIS.