Duct carcinoma in situ: A personal perspective

In the recent past, DCIS was a rare diagnosis established by biopsy of palpable breast masses or nipple changes. Mammography increased the frequency of a DCIS diagnosis by 20 × resulting in a tsunami of small circa 10 mm lesions detected only by mammography. The impact of pathologic technique in examining and characterizing such lesions is reviewed, and the development of algorithms incorporating prognostic factors and histology based on serial sequential processing techniques are described and contrasted with those which relied on tissue sampling. The development of the initial clinical trails of irradiation all demonstrated the significant benefit of irradiation but none could identify subsets with a more favorable outcome. The latter was precluded by their common practice of tissue sampling: Size could not be calculated and margin width and microinvasion could not be reliable demonstrated. Multigene signature assays are increasingly being utilized, most prominently Oncotype DCIS. However, these assays must be interpreted in conjunction with the limitations set forth in the validating studies-in the case of Oncotype DCIS-the size, margin width, and grade which defined the baseline study (E5194). Tamoxifen and other anti-hormonal agents (aromatase inhibitor therapy) have been shown to have a limited impact on ipsilateral recurrence which makes their use given their morbidities problematic. Such interventions do impact the frequency of contralateral occult in situ and invasive lesions. In the one study which permitted a comparison of local recurrence in irradiated vs nonirradiated breast, there was no added benefit of Tamoxifen in irradiated breasts. Some are attempting to identify a low-risk subset of DCIS which can be treated without surgical re-excision for margins or adjuvant irradiation. These studies are in progress but surrogates identified within the Van Nuys prospective series defined by grade and inadequate margins (≤ 1 mm) would suggest a significant recurrence and progression rate. DCIS remains a work in progress both in terms of classification and treatment. However, limited our progress in these areas we have certainly advanced from the oft-proclaimed mantra: "Radiation and Tamoxifen are standard of care."