Recent studies in The Cancer Genome Atlas Research Network (TCGA) shed more light on the gene deletions, mutations and amplifications commonly seen in ILC [46, 104]. Comprehensive genomic and transcriptomic analysis of breast cancers show that the major differences between ILC and IDC are mutations in TP53, PIK3CA, GATA3, MYC, MAP3K1/MAP2K4, which are more common in IDC versus PIK3CA, FOXA1, HER2 and PTEN which are more common in ILC. It is important to emphasize that the rate of HER2 gene mutation is much higher in ILC (10 % vs. <1 %), whereas HER2 gene amplification is more common in IDC (15 % vs. <5 %) [46]. The biologic significance and clinical utility of some of these alterations will need to be elucidated with further comprehensive molecular studies.

There is little known about the hereditary genetics of lobular cancer. Current evidence suggests that there is a significant overlap between genetic predisposition to IDC and ILC. However, newer studies have identified novel nucleotide polymorphisms at locus 7q34 conferring a predisposition that is specific to lobular breast cancer [105].

Molecular characterization of lobular carcinomas in the literature is relatively limited. With the advent of more advanced and readily available technologies additional molecular findings will likely emerge.