Duct carcinoma in situ: biological implications for clinical practice.

Duct carcinoma in situ (DCIS) has become an important, however controversial, focus of breast cancer management only since the advent of effective film mammography and the development of an increased interest and utilization of breast conservation therapy. Prior to 1975, DCIS remained an infrequent biopsy finding in patients who presented with a palpable mass, nipple discharge, or clinical Paget's disease. The vast majority of such patients harbored extensive noninvasive disease and frequently were found to have occult invasive breast cancer at mastectomy, which was the only method of available treatment. The significance of small foci of DCIS as detected mammographically and the implications of DCIS in conjunction with invasive carcinoma for breast conservation therapy were slowly learned over the next two decades. This paper reviews current studies of DCIS with a particular focus on practical applications for management.