Abstract P1-01-11: Nuclear immunohistochemical IKK-ϵexpression in flat epithelial atypia (FEA) of the breast: A predictor of ipsilateral ADH, in-situ or invasive malignancy?
Authors: Williams PA , Parra-Herran CE , Ayroud Y , Islam S , Gravel DH , Robertson SJ , Pratt C 
Published: May 2016

Background:Flat Epithelial Atypia of the breast (FEA) is associated with in situ and invasive low grade neoplasia. However, the role of excision after FEA on biopsy is controversial as rates of upgrading to atypical ductal hyperplasia (ADH), ductal carcinoma in situ (DCIS) or invasive carcinoma in subsequent excision are relatively low. Problems include difficulties in inter-observer reproducibility and lack of morphologic or immunohistochemistry (IHC) tools that better identify cases at risk for concurrent ADH/Carcinoma. Nuclear image analysis may be useful, but is not widely available. IKK-ϵ, part of the NF-kB activating pathway, is absent in normal breast epithelium and non atypical (usual) ductal hyperplasia, but is over-expressed in &gt;30% of breast cancers. In addition, in our experience ADH/DCIS shows IKK-ϵ staining, mostly cytoplasmic. Of note, in prostate cancer, nuclear accumulation of IKK-ϵ has been described in hormone sensitive prostate disease while cytoplasmic accumulation is associated with metastatic progression. No previous studies of IKK-ϵ levels in FEA are reported. Here we report IKK-ϵ status in FEA and correlation with ipsilateral, synchronous ADH, DCIS or invasive carcinoma.

Method: Resection specimens from 61 patients with diagnosis of FEA were retrieved. Presence of ADH/carcinoma and laterality (ipsi or contralateral) was recorded. Synchronous neoplasia was defined as ADH, DCIS or invasive carcinoma diagnosed within 6 months of the diagnosis of FEA. Presence of FEA was confirmed by three observers using strict morphologic criteria. IHC for IKK-ϵ was performed using ABCAM, rabbit anti-IKK-ϵ (ab7891) and pH 6 citrate buffer heat-induced epitope retrieval for 20 minutes. IHC slides were scanned and FEA regions captured for blind scoring of nuclear and cytoplasmic staining. Cut off for positive nuclear staining was 10% and cytoplasmic staining was graded as negative, weak, moderate or strong positive.

Results:40 patients had ipsilateral synchronous ADH/carcinoma, and 21 did not. Within these groups, 6 patients had contralateral ADH/carcinoma (2 with and 4 without ipsilateral neoplasia). While cytoplasmic staining showed no difference between the groups, nuclear positivity was more frequent in cases with ipsilateral synchronous ADH/carcinoma, χ2(1, N = 61) = 5.1, p = .025 (Table 1). In contrast, there was no correlation between IKK-ϵ staining and ADH/carcinoma in the opposite breast (p=.25).

Table 1Nuclear IKK-eSynchronous Ipsilateral ADH/DCIS/Carcinoma Negative (%)Positive (%)TotalNegative10 (48)11 (52)21Positive10 (25)30 (75)40

Conclusion:Nuclear IKK-ϵ staining may prove useful in predicting synchronous ipsilateral ADH or malignancy in cases of FEA in biopsy material. Given its more frequent association with ipsilateral synchronous ADH/carcinoma, IKK-ϵ nuclear expression in FEA may represent a step in continuous local oncogenesis rather than a general marker of risk. Given the pleiotropic role of IKK-ϵ in growth and survival, the significance of the shift from nuclear staining in FEA to cytoplasmic staining in ADH/DCIS may reflect different signaling pathways and requires further investigation. Further validation of our findings in larger cohorts is necessary.

Citation Format: Williams PA, Parra-Herran CE, Ayroud Y, Islam S, Gravel DH, Robertson SJ, Pratt C. Nuclear immunohistochemical IKK-ϵexpression in flat epithelial atypia (FEA) of the breast: A predictor of ipsilateral ADH, in-situ or invasive malignancy?. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-01-11.