RAISE YOUR HAND IF YOU DON’T KNOW WHETHER TO EXCISE FLAT EPITHELIAL ATYPIA FOUND ON CORE BIOPSY
This meta-analysis may be helpful
Flat epithelial atypia (FEA) was first described in 1979 and was designated as “clinging carcinoma in situ”. Since then, it has been described in a variety of nomenclatures. Without a unified name or clear pathological description, in 2003, the World Health Organization (WHO) introduced the name FEA and defined it as a neoplastic intraductal alteration with replacement of native epithelial cells with 1-5 layers of monotonous cuboidal or columnar cells with apical snouts. It differs from columnar cell change or hyperplasia by the presence of mild cytologic atypia. It differs from atypical ductal hyperplasia (ADH) and ductal carcinoma in situ (DCIS) by the absence of architectural atypia. When diagnosed by core needle biopsy (CNB), flat epithelial atypia (FEA) is a breast lesion for which there is disagreement as to whether surgical excision is necessary due to a potential upgrade to cancer, ADH, atypical lobular hyperplasia (ALH) or lobular carcinoma in situ (LCIS).
Due to lack of consensus, Rudin et al. from the Mayo Clinic, performed a meta-analysis. The primary endpoint was upgrade to cancer in 32 studies, 22 studies with an upgrade to cancer and ADH and 9 studies reporting on an upgrade to cancer, ADH, ALH and LCIS.
The pooled rate of cancer upgrade was 11.1%. Many of these studies included patients diagnosed prior to 2003, when FEA was formalized by the WHO. When studies were restricted to those after 2003, the upgrade estimate was lower at 7.5% and included both invasive and in situ cancer (DCIS) with upgrade to invasive cancer being less common (3%). Approximately 18% of patients were upgraded to ADH. In this case, there was little impact noted based on year of publication. An upgrade to any high-risk lesion was 27.1% (CI 18.9-37.2%) but there was a good deal of heterogeneity in these studies.
Due to the rarity of pure FEA on CNB and the lack of consistent terminology it has been difficult to come to consensus as to management. From this meta-analysis, if one accepts a conservative estimate of a 7% upgrade to cancer and at least 15% upgrade to ADH, it suggests that near a quarter of patients would have pertinent clinical information with surgical excision. This allows the clinician to offer patients the opportunity to discuss chemoprevention or a change in surveillance.