The association of ethnicity and the incidence of mammary carcinoma in situ in women: 11,436 cases from the California Cancer Registry.

Ethnic differences in the incidence of mammary carcinoma in situ (CIS) in women, as well as differences in the percentages of carcinomas diagnosed in the in situ stage, have been calculated from the 11,436 cases of CIS in the California Cancer Registry (CCR) for the years 1988 through 1992. White women have an average annual age-adjusted incidence (AAAIR) of 17.4/100,000; black women, 11.4/100,000; Hispanic women, 7.6/100,000; and Asian/other women, 8.3/100,000. White women have 11.8% of their carcinomas diagnosed in the in situ stage; black women, 10.2%; Hispanic women, 9.7%; and Asian/other women, 12.2%. In all ethnicities, CIS is predominantly a disease of postmenopausal women and is first diagnosed at an earlier age in nonwhite women. All of these observations have implications in the planning and evaluation of health care delivery and cancer control activities. Moreover, the younger age at diagnosis of women with CIS compared with those with invasive carcinoma supports the concept that CIS proceeds to invasive cancer.