The Changing Paradigm of Lobular Neoplasia of the Breast

Lobular neoplasia is a spectrum of proliferative lesions that includes atypical lobular hyperplasia (ALH) and lobular carcinoma in situ (LCIS). When it was first described, LCIS was considered to be a precursor of invasive lobular carcinoma, and was therefore treated with unilateral mastectomy. Gradually, both ALH and LCIS came to be thought of as markers for the development of malignancy in either breast rather than premalignant precursors, and mastectomy for LCIS was abandoned. The most recent data suggest that LCIS may, in selected circumstances, have a behavior more similar to low-grade ductal carcinoma in situ (DCIS). This has led to a reevaluation of the role of surgical treatment for selected atypical cases of LCIS. Definitive data are lacking in this area, particularly with the most histologically aggressive form of lobular neoplasia, pleomorphic LCIS (pLCIS). ALH and LCIS are typically diagnosed incidentally during biopsy for another indication. When seen on core needle sampling, diagnostic surgical biopsy is recommended, because 7% to 10% of patients will be found to have DCIS or invasive cancer at the site of the needle sampling. Because lobular neoplasia is associated with heightened breast cancer risk, careful surveillance is indicated after a complete diagnostic workup. Mastectomy is not indicated for treatment, although bilateral prophylactic mastectomy could be considered in unusual circumstances where other strong risk factors prevail. The lifetime risk of an invasive cancer developing appears to be between 10% and 25% following a diagnosis of lobular neoplasia, which can be decreased by the use of a chemopreventive endocrine agent, such as Tamoxifen.