Results From a Cohort Study

jnci.oxfordjournals.org JNCI | Articles 243 The incidence of ductal carcinoma in situ (DCIS) is increasing among American women. Until approximately 20 years ago, DCIS represented only a small percentage of all diagnosed breast cancers ( 1, 2). The increasing use of screening mammography has had a substantial impact on the increasing frequency with which DCIS is diagnosed ( 3 – 5). According to data provided by the Surveillance, Epidemiology, and End Results Program of the National Cancer Institute, the incidence of DCIS increased dramatically from 1983 to 1996 ( 6). Among women younger than 50 years, incidence increased 131 % among white women and 190 % among black women. Among white and black women aged 50 years and older, the increases observed were 275 % and 313%, respectively ( 5). In 2006, nearly 62 000 cases of DCIS were diagnosed in the United States, representing more than 20 % of all breast cancer diagnoses ( 7). DCIS is a complex clinical entity that is highly variable in its appearance, biology, and behavior ( 4, 8). Age at diagnosis, extent of disease, pathologic subtype (comedo vs noncomedo, high grade vs low grade), and treatment all infl uence risk of recur-rence ( 8). These factors, as well as patient preferences and physi-cian recommendations, infl uence decisions about treatment options that include mastectomy, breast-conserving surgery wit