Pathology of ductal carcinoma in situ of the breast: current status.

Ductal carcinoma in situ (DCIS) now accounts for around 20-25% of mammographically detected breast cancers. There is strong evidence to show that classification schemes for DCIS should be based primarily on nuclear grade and necrosis as these two features have been shown to be prognostically important as well as having high interobserver reproducibility among pathologists. Newer classifications of DCIS that employ these features, such as the Van Nuys DCIS Classification, are of prognostic importance in predicting recurrence of DCIS after breast conservation and show high levels of reproducibility. For treatment of DCIS via breast conservation a high pre-operative diagnostic rate is desirable, only achievable via needle-guided core biopsy. If local excision without radiotherapy is to be given there is strong evidence to support the requirement for a 10 mm tumour-free margin. Assurance that a margin is tumour-free requires sequential specimen processing which is both time consuming and costly, but which can be justified in cost and morbidity terms as radiotherapy may not be required for those patients with a 10 mm tumour-free margin. Other methods of specimen examination involve examination of mammographically directed tissue slices or alternative methods of excision margin assessment such as "onion skinning" of the specimen. Endocrine therapy will doubtless become more important for adjuvant therapy of DCIS as well as chemoprophylaxis in the future.