Comparative genomic hybridisation analysis of myoepithelial carcinoma of the breast

Excerpt

Although there appears to be a common stem cell for the two epithelial cell types in the breast, the majority of breast cancers exhibit a luminal phenotype. Pure myoepithelial carcinomas are rare. We report our findings of genetic alterations in these tumours. We have analysed 10 cases of pure spindle cell myoepithelial carcinomas using laser capture microdissection and comparative genomic hybridisation. The mean number of changes was 2.1 (range 0-4), compared to a mean of 8.6 (range 3.6-13.8) in unselected ductal carcinomas. Common alterations included loss at 16q (3/10 cases), 17p (3/10), 11q (2/10) and 16p (2/10), regions also commonly deleted in ductal carcinomas. The single case in which both pure myoepithelial carcinoma and invasive ductal carcinoma was present showed two alterations in the myoepithelial tumour (losses at 17p and 17q), while the invasive ductal component showed fourteen alterations (5 gains and 9 losses), including loss at 17p. The sharing of 17p loss in myoepithelial and ductal carcinoma is consistent with a common stem cell model in the breast. The relatively few genetic alterations in otherwise aggressive neoplasms suggests that myoepithelial tumours may be a good model for the delineation of genes important in breast tumorigenesis. …