Molecular phenotypes of ductal carcinoma-in-situ and invasive ductal carcinoma: a comparative study

This study was aimed at analyzing the prevalence of molecular phenotypes in invasive ductal carcinoma (IDC) and coexisting ductal carcinoma-in-situ (DCIS) and to correlate with clinicopathological features.

In this study, 75 cases of IDC with coexisting DCIS were included. Molecular phenotype was determined using expression of estrogen receptor, progesterone receptor, HER2/neu, and cytokeratin 5/6. Statistical analysis was performed for correlation between molecular phenotypes and clinicopathologic parameters.

Of the 75 cases, the invasive component in all cases was IDC--not otherwise specified. About one-third of our patients were post-menopausal. The most common molecular phenotype was luminal A (45.3%) followed by HER2-expressing type (24%). In all cases, the molecular phenotype was identical in DCIS and the invasive component. HER2-expressing tumors were found to be larger in size with frequent nodal involvement. On statistical analysis, tumor size and grade were found to correlate with the molecular phenotype.

In conclusion, the molecular phenotype in DCIS correlates well with that of coexisting IDC, suggesting that DCIS is a precursor lesion in these tumors. This correlation of molecular phenotype can be utilized in prediction of phenotype of the invasive component in a case with in-situ carcinoma.