Differences between invasive lobular and invasive ductal carcinoma of the breast: results and therapeutic implications.

Invasive lobular carcinoma (ILC) is the second most common histologic subtype of breast cancer (BC): ILC differs from invasive ductal carcinoma (IDC) in its clinicopathological characteristics and responsiveness to systemic therapy. From the clinical standpoint, data suggest that ILC derives a distinct benefit from systemic therapy compared to IDC. In addition, comprehensive molecular analyses have been reported for ILCs, confirming that these tumors have specific genomic profiles compared to IDC. Despite these differences, clinical trials and practical clinical guidelines tend to treat BC as a single entity. Here we discuss these clinical and molecular data and their therapeutic implications.