for those wondering what REALLY is the difference between DCIS and IDC

[Lani]

As I remember posts from members who started with "just DCIS" but progressed to Stage four it seems many may wonder ...what happened and wonder what is it that makes one lump DCIS and another IDC and, therefore, capable of metastasizing according to the current thinking (which may be changing)...Is one just an earlier version of the other...why don't all DCIS become IDC...how do you predict which DCIS will become IDC in order to treat different DCISs differently and appropriately? Again, the answer seems to come from individualized treatment based on prognosis based on gene profiling. This article comes from the same group in the Netherlands that came up with the 70 gene profile (not yet commercial) for IDC.

Classification of ductal carcinoma in situ by gene expression profiling
Juliane Hannemann , Arno Velds , Johannes BG Halfwerk , Bas Kreike , Johannes L Peterse and Marc J van de Vijver

Breast Cancer Research 2006, 8:R61 doi:10.1186/bcr1613

Published 30 October 2006

Abstract (provisional)

The complete article is available as a provisional PDF. The fully formatted PDF and HTML versions are in production.


Introduction

Ductal carcinoma in situ (DCIS) is characterized by the intraductal proliferation of malignant epithelial cells. Several histological classification systems have been developed, but assessing the histological type/grade of DCIS lesions is still challenging, making treatment decisions based on these features difficult. To obtain insight in the molecular basis of the development of different types of DCIS and its progression to invasive breast cancer, we have studied differences in gene expression between different types of DCIS and between DCIS and invasive breast carcinomas.

Methods

Gene expression profiling using microarray analysis has been performed on 40 in situ and 40 invasive breast cancer cases.

Results

DCIS cases were classified as well (n=6), intermediately (n=18) and poorly (n=14) differentiated type. Of the 40 invasive breast cancer samples, 5 samples were grade I, 11 samples were grade II and 24 samples were grade III. Using two-dimensional hierarchical clustering, the basal-like type, ERB-B2 type, and the luminal type tumors originally described for invasive breast cancer could also be identified in DCIS.

Conclusions

Using supervised classification, we identified a gene expression classifier of 35 genes, which differed between DCIS and invasive breast cancer; a classifier of 43 genes could be identified separating between well and poorly differentiated DCIS samples.