Summary

Invasive lobular carcinoma (ILC) is the second most common breast cancer histologic subtype, accounting for 10% to 15% of all breast cancers, with classic lobular carcinoma being the most common variant. Aromatase inhibitors and tamoxifen are established therapies used for the adjuvant treatment of estrogen receptor-positive breast cancer, but the relative benefits in invasive ductal carcinomas (IDCs) and ILCs has not been extensively studied. This article presents an analysis of the Letrozole or Tamoxifen in Treating Postmenopausal Women with Breast Cancer [BIG 1–98] trial comparing the outcomes of patients with IDC and ILC treated with adjuvant letrozole or tamoxifen.