Prognosis in carcinoma in situ of the breast

Abstract: The incidence of breast cancer is rising steadily in Sweden and the proportion of carcinoma in situ (CIS) has increased appreciably, most likely due to mammography screening. The aim of this study was twofold: (1) to examine risk factors for subsequent invasive breast carcinoma and breast cancer death after primary ductal carcinoma in situ (DCIS) and (2) to study the biology in the progress between in situ and invasive carcinoma. In a cohort-study based on 3,398 women with a primary CIS reported to the Swedish Cancer Registry (SCR) 1980-1992, women diagnosed in 1989-1992 ran a relative risk of 0.1 (CI 95%, 0.0-0.9) from dying of breast cancer as compared with women diagnosed in 1980-1982. Women in counties with mammography screening ran a relative risk of 0.2 (CI 95%, 0.0-2.1) for breast cancer death in comparison with women in non-screening counties. In a case-control study derived from all 4,661 women with primary CIS reported to the SCR 1960-1992, we investigated risk factors for subsequent invasive breast carcinoma (n=118) and breast cancer death (n=39). Large size and multifocality were found to increase the risk for breast cancer death. Postoperative radiotherapy and mastectomy lowered the risk for ipsilateral invasive cancer. The standardised incidence rates (SIR) for invasive breast cancer were estimated in the cohort from 1980-1992. The SIR after primary DCIS and primary lobular carcinoma in situ (LCIS) was 4.5 (CI 95%, 3.7-5.5) and 4.0 (CI 95%, 2.1-7.5), respectively. New histopathological classification systems for DCIS were evaluated in 195 women consecutively diagnosed with primary DCIS between 1986-1994. One group with highly differentiated lesions was defined with the EORTC classification system and had an excellent prognosis. Histopathological grade and expression of p53, c-erbB-2, Ki 67, hormone receptors, Bcl-2 and angiogenesis were compared in 626 women with either a pure DCIS, a small invasive carcinoma or a lesion with both an invasive and in situ component. When grade was taken into account, no change in tumour markers could be detected that signalled the progression from an in situ stage to invasiveness. All tumour markers correlated to grade and their distribution was very similar in the two components of mixed lesions.