Infiltrating lobular carcinoma of the breast: systemic treatment

Invasive lobular carcinoma (ILC) is the second most common type of breast cancer after invasive ductal carcinoma (IDC). It is characterized by unique clinical, biological and molecular properties. ILC is almost always positive for the estrogen receptor and is typically of a lower grade compared with IDC. We have reviewed selected literature on preoperative (neoadjuvant) and adjuvant systemic therapy of breast cancer focusing on the differential therapy of ILC. Despite the importance of this type of breast cancer, information about its specific treatment is sparse, in particular with regard to adjuvant systemic chemotherapy. ILC has significantly lower rates of response to neoadjuvant chemotherapy compared with IDC; however, the low chemosensitivity seems not to result in a survival disadvantage. Adjuvant hormonal therapy studies do not distinguish between ILC and IDC. Thus, recommendations about endocrine therapies are made using the same criteria as for IDC.