Expression of Lipid Metabolism-Related Proteins Differs between Invasive Lobular Carcinoma and Invasive Ductal Carcinoma

We comparatively investigated the expression and clinical implications of lipid metabolism-related proteins in invasive lobular carcinoma (ILC) and invasive ductal carcinoma (IDC) of the breast. A total of 584 breast cancers (108 ILC and 476 IDC) were subjected to tissue microarray and immunohistochemical analysis for lipid metabolism-related proteins including hormone-sensitive lipase (HSL), perilipin A, fatty acid binding protein (FABP) 4, carnitine palmitoyltransferase (CPT)-1, acyl-CoA oxidase 1, and fatty acid synthetase (FASN). HSL, perilipin A, and FABP4 expression (all p < 0.001) differed significantly: HSL and FABP4 were more frequently present in ILC, whereas perilipin A was more frequently detected in IDC. Among all invasive cancers, HSL and FABP4 were highly expressed in luminal A-type ILC (p < 0.001) and perilipin A in luminal A-type IDC (p = 0.007). Among luminal B-type cancers, HSL and FABP4 were more highly expressed in ILC (p < 0.001). Univariate analysis found associations of shorter disease-free survival with CPT-1 positivity (p = 0.004) and acyl-CoA oxidase 1 positivity (p = 0.032) and of shorter overall survival with acyl-CoA oxidase 1 positivity (p = 0.027). In conclusion, ILC and IDC exhibited different immunohistochemical lipid metabolism-related protein expression profiles. Notably, ILC exhibited high HSL and FABP4 and low perilipin A expression.