Ductal carcinoma in situ (DCIS) now accounts for 20-30% of all newly d
iagnosed breast cancers in centers which use mammographic surveillance
as a standard part of the examination. The majority of these DCIS les
ions, at least in the United States, are of very limited size, with me
an estimated extents of 8-20 mm based on pathological examination. A s
mall fraction of these are incidental microscopic features of the biop
sy; the majority are detected on the basis of mammographic microcalcif
ications. These mammographically detected DCIS lesions are biologicall
y heterogeneous, and this is reflected by their histology. Moreover, a
number of recent independent studies have shown that the clinical out
come of patients, particularly those treated by breast conservation, i
s related to the presence of reproducible and identifiable histologic
features, and possibly to certain immunohistochemically demonstrable g
ene markers as T well. Nuclear and proliferative features of DCIS, as
well as an evaluation of the periductular stroma, will be major focuse
s for the surrogate endpoint biomarker proposal. (C) 1994 Wiley-Liss,
Inc.