The incidence of
ductal carcinoma in situ (
DCIS) has markedly increased as a result of the use of screening mammography. Whether
DCIS is a premalignant lesion or a
cancer remains a cause of debate, but evidence supports the idea that
DCIS evolves into invasive
breast cancer based on histologic patterns, similar risk factors, and genetic similarities.
Microcalcifications identified during mammography generally raise the suspicion of
DCIS, and biopsy, often by core needle, confirms such a diagnosis. The extent of disease can be further delineated by breast magnetic resonance imaging.
Radiation therapy in breast-conserving treatment, along with
tamoxifen, decreases the overall rate of local recurrence in patients with
DCIS. Studies in the treatment of
DCIS exploring partial breast radiation and
trastuzumab are under way. Ongoing investigations with comparative genomic hybridization suggest that there are independent, evolutionary genetic pathways within
DCIS. Genome-wide microarray-based gene expression analyses are now providing new opportunities to discover genes that are specifically activated or inactivated during the course of
breast cancer progression.