Perspectives on margins in DCIS: pathology.

All breast carcinomas must originate within the ductal/lobular system as carcinoma in situ, but only a subset of these lesions progress to invasive carcinoma. Although pathologic evaluation of the extent of ductal carcinoma in situ (DCIS), the distance to margins, and the degree of margin involvement provides an estimation of the likelihood of residual disease, the amount of disease in the remaining breast cannot be predicted with certainty. Factors other than residual disease may be more important in determining whether patients with DCIS survive or succumb to breast cancer, including biologically new ipsilateral cancers, contralateral cancers, and the degree of resistance of the normal stroma to invasion.