Comparison of Xpert® Breast cancer STRAT4 assay and immunohistochemistry for the evaluation of breast cancer biomarkers in South African patients

Dube, Welile Vumile (2020-12)

Thesis (MMed)--Stellenbosch University, 2020.

Thesis

Background: Breast cancer is one of the most common cancers diagnosed in women and approximately 60% of breast cancer related deaths are reported in low-and middle-income countries. Breast cancer is a highly heterogeneousdisease, and molecular subtyping is paramount foreffective treatment of patients. Therefore, it is important to validate new molecular methods for assessing cancer biomarkers for cost-effective use in resource-poor settings.Aim:Aretrospective study was performed to determine the concordance between aQuantitativeReverse TranscriptionPolymerase Chain Reaction(RT-qPCR) CE-IVD assay (Xpert® Breast Cancer STRAT4*) and the current gold standard methods of immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) for determining estrogenreceptor (ER),progesterone receptor(PR), human epidermal growth factor receptor 2 (HER2)andproliferation index(KI-67)expression in breast carcinomas.Method: One hundred and one cases of breast carcinoma were retrieved from the archives of the Division of Anatomical Pathology, Tygerberg Academic Hospital. The original stained slides were reviewed and IHC expression of ER, PR, HER2 and KI-67 scored. Three-micron sections were cut from formalin-fixed paraffin embedded (FFPE) tissue blocks and processed according to the instructions of the manufacturer. The assay was run on the resultant lysates.Results:The overall percentageagreement between the Xpert® STRAT4 assay and IHC / FISH results were 85.15% for ESR, 89.90% for PGR,91.09% for ERBB2, 90.72% for MKI67 (when using a cut off of 10%) and 84.54% for MKI67 (when using a cut-off of 20%). The positive percentage agreement for ESR, PGR, ERBB2, MKI67 with 10% cut-off andMKI67 with 20% cut-offwere 82.76%, 94.64%, 68.97%, 91.30% and 96.05%, respectively, and the negative percentage agreement were 100%, 84.09%, 91.67%, 80.00% and 42.86%, respectively. Conclusion:The studyhas shownthattheXpert® BreastCancer STRAT4 assay shows good concordance with IHC and FISH in detecting breast cancer biomarkers, and may become a supplementary or alternativestandard of care aftervalidation studies are performed.

Agtergrond: Borskanker is een van die algemeenste kankers wat by vroue gediagnoseer word en ongeveer 60% van sterftes wat metborskanker verband hou, word in lande met lae en middle-inkomste aangemeld. Borskanker is 'n hoogs heterogene siekte, en molekulêre subtipes is van uiterse belang vir die effektiewe behandeling van pasiënte. Daarom is dit belangrik om nuwe molekulêre metodes te evalueer vir die bepaling van kankerbio-merkers vir koste-effektiewe gebruik in hulpbron-arm instellings.Doel: 'n Terugwerkende studie is uitgevoer om die ooreenkomstussen 'n RT-qPCR CE-IVD-toets (Xpert®Borskanker STRAT4*) en die huidige goudstandaardmetodes vanimmunohistochemie (IHC) en fluoresensie in situ-hibridisasie (FISH) om dieuitdrukKIng van estrogeen reseptor (ER), progesteroon reseptor (PR), menslike epidermale groeifaktor reseptor 2 (HER2)en proliferasie indeks (KI-67)te bepaal inborskarsinoom. Metode: Honderd-en-een gevalle van borskarsinoom is uit die argiewe van die Afdeling Anatomiese Patologie, Tygerberg Akademiese Hospitaal,geselekteer. Die oorspronklike gekleurde skyfies is hersien omdie IHC-uitdrukKIng van ER, PR, HER2 en KI-67 te bepaal. Drie-mikronsnitteis vandie formalien vaste paraffien-ingebedde weefselblokke gesny en volgens die instruksies van die vervaardiger verwerk. Die toets is uitgevoer op die resulterende lisate.Resultate: Die algehele persentasie-ooreenkoms tussen die Xpert® STRAT4-toets en IHC / FISH-resultate was 85,15% vir ESR, 89,90% vir PGR, 91,09% vir ERBB2, 90,72% vir MKI67(wanneer 'n afsnypuntvan 10% gebruik is) en 84,54% vir MKI67(met'n afsnypunt van 20%). Die positiewe persentasieooreenkoms vir ESR, PGR, ERBB2, MKI67met 10% afsnypunten MKI67met 20% afsnyspuntwas onderskeidelik 82,76%, 94,64%, 68,97%, 91,30% en 96,05%, en die negatiewe persentasieooreenkoms was 100%, 84,09%, 91,67%, 80,00% en 42,86%, onderskeidelik. GevolgtrekKIng: Die studie het getoondat Xpert® borskankerSTRAT4-toetsing goeie ooreenstemming met IHC en FISH toon virdie opsporing van biomerkers in borskanker, en dit kan 'n aanvullende of alternatiewe standaard vir sorg word nadat meer valideringstudies gedoenis.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/109372
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