Comparison Of Biomarker Expression Between Biopsy And Surgical Specimens Of Non-Small-Cell Lung Cancer. Assessement By Immunohistochemical Staining

Abstract

2Corresponding author's email: okimoto@med.shimane-u.ac.jp RATIONALEIn recent years, etiology, pathogenesis, and tolerance mechanisms of lung cancers are being explained by many researchers and we have to take account of them when we decide the treatment strategy. There may be somewhat potential heterogeneity in one tumor specimen and whether there is a correlation of expression of biomarkers between surgical samples and diagnostic biopsy samples is controversial. How to evaluate the biomarker expression is unsettled, too. Some use mRNA and others use immunohistochemical staining. In this study, we compared the expression of biomarkers by immunohistochemical staining in order to assess the correlation between surgical samples and diagnostic biopsy samples and the usefulness of immunohistochemical staining. METHODS We retrospectively collected lung cancer patients who were diagnosed by diagnostic biopsy and went through an operation between . We identified 31 patients. The diagnostic procedures included transbronchial lung biopsies (TBLB) (n=16) and percutaneous computed tomography (CT) guided lung biopsies(n=16). We assessed three predictive biomarker expression, excision repair cross-complementing gene 1 (ERCC1), ribonucleotide diphosphate reductase M1 (RRM1), thymidylate synthase (TS), and we compared by immunohistochemical staining between diagnostic biopsy and corresponding resected surgical specimen. Expression scores of the each marker were dichotomized into negative and positive, using average scores of the each biomarker of the surgical specimens. RESULTS Moderate correlation coefficients were observed between the expression of ERCC1 and RRM1 in the biopsies and the surgical specimens [(r=0.512, (p=0.003) and r=0.439 (p=0.012), respectively]. on the other hand, low correlation coefficients were observed between the expression of TS (r=0.301, p=0.094). The diagnostic procedure, TBLB or CT guided biopsie, did not influence the concordance rate. In most cases discordance between biopsies and surgical specimens were observed, biopsy specimens were negative and surgical specimens were positive (79.4%). CONCLUSION We showed correlation between biopsy specimens and surgical specimens. When we use immunohistochemical staining to evaluate the biomarker expression, negative expression may mislead us, but positive expression is reliable because of high concordance rate. If we would like to use it as a decision making tool, larger clinical trials are needed.