70P - Discordance with estrogen receptor alpha status estimated by immunohistochemical and immunofluorescent method associated with flowcytometry in breas...

Date 07 May 2015
Event IMPAKT 2015
Session Welcome reception and Poster Walk
Topics Basic Science
Breast Cancer
Pathology/Molecular Biology
Presenter Maria Rodionova
Citation Annals of Oncology (2015) 26 (suppl_3): 15-24. 10.1093/annonc/mdv117
Authors M.V. Rodionova1, T.A. Bogush2, E.A. Dudko2, E.A. Shestakova2, E.A. Bogush3, V.J. Kirsanov3, I.K. Vorotnikov1
  • 1Surgical Department (breast Cancer Department), N. N. Blokhin Russian Cancer Research Center, 115478 - Moscow/RU
  • 2Laboratory Of Medical Chemistry, N. N. Blokhin Russian Cancer Research Center, 115478 - Moscow/RU
  • 3Surgical Department, N. N. Blokhin Russian Cancer Research Center, 115478 - Moscow/RU

Abstract

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Background: Estrogen receptors alpha (ER) are one of the most important breast cancer prognostic and predictive markers but routine immunohistochemical (IHC) methods do not allow accurate ER determination because of semi-quantitative assay and tumor heterogeneity. To avoid the problems an accurate quantitative immunofluorescent method associated with flowcytometry (FC) that allows the investigation up to 10.000 cells from several parts of the tumor was used for the comparison of IHC and FC data of ER expression.

Materials and methods: 55 breast cancer surgical specimens were analyzed by FC after incubation with primary (ab27614) and secondary antibodies (ab98510). Cell fluorescence was analyzed with FlowJo 7.6.1 software and Kolmogorov-Smirnov statistical approach. The indexes of ER expression were: ER –, low and high ER level that correspond, respectively, to IHC – <1%; 1-40%; >40% and to FC – <15%; 15-40%; >40%.

Results: 1. The number of ER– and ER+ tumors detected by IHC or FC was about the same (30% and 70%, respectively). 2. Discordance between IHC and FC indexes in the same tumors was significant. 40% of IHC ER– tumors were classified as ER+ by FC. Opposite, 30% of the IHC ER+ tumors were classified as ER– by FC. 3. 15% of ER negative as well as 35% and 50% of the ER+ tumors with low and high level of ER expression was revealed by FC in the group with high ER+ level 65-100% detected by IHC. So, accurate quantitative indexes of ER+ expression detected by IHC or FC were similar in only half of cases.

Conclusion: Discordance with breast cancer ER status analyzed either with IHC or FC methods in various paraffin blocks as well as between paraffin blocks of the same surgical sample supports a contribution of tumor heterogeneity in inexactitude of ER breast cancer status. Solely IHC investigation is not accurate enough for the final conclusion. That is why repeated IHC analysis of different paraffin blocks in association with FC investigation of the same tumor surgical sample is needed to characterize ER tumor status in a more precise way. Supported by RFBR (13-04-01004a, 15-04-06991a, 14-04-31734mol-a), scholarship of the President of RF (376.2012.4.), RAS (FIMT-2014-205).

Disclosure: All authors have declared no conflicts of interest.