Discordance of Molecular Biomarkers Associated with Epidermal Growth Factor Receptor Pathway between Primary Tumors and Lymph Node Metastasis in Non-small Cell Lung Cancer

Park, Sarah; Holmes-Tisch, Alison J.; Cho, Eun Yoon; Shim, Young Mog; Kim, Jinkook; Kim, Hyo Song; Lee, Jeeyun; Park, Yeon Hee; Ahn, Jin Seok; Park, Keunchil; Jänne, Pasi A.; Ahn, Myung Ju

doi:10.1097/jto.0b013e3181a94af4

Cited by 136 publications

(82 citation statements)

References 34 publications

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“…As a reliable estimate of the tumor cell percentage is especially important in tissue samples with tumor cell percentages around the diagnostic threshold of the molecular test, we focused on the eight slides containing o20% of tumor cells (close to the percentage of tumor cells required for direct sequencing 4,5 ). Twenty-seven of the 72 (38%) estimates on these slides were 420% tumor cells.…”

Section: Resultsmentioning

confidence: 99%

The estimation of tumor cell percentage for molecular testing by pathologists is not accurate

et al. 2014

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Molecular pathology is becoming more and more important in present day pathology. A major challenge for any molecular test is its ability to reliably detect mutations in samples consisting of mixtures of tumor cells and normal cells, especially when the tumor content is low. The minimum percentage of tumor cells required to detect genetic abnormalities is a major variable. Information on tumor cell percentage is essential for a correct interpretation of the result. In daily practice, the percentage of tumor cells is estimated by pathologists on hematoxylin and eosin (H&E)-stained slides, the reliability of which has been questioned. This study aimed to determine the reliability of estimated tumor cell percentages in tissue samples by pathologists. On 47 H&E-stained slides of lung tumors a tumor area was marked. The percentage of tumor cells within this area was estimated independently by nine pathologists, using categories of 0-5%, 6-10%, 11-20%, 21-30%, and so on, until 91-100%. As gold standard, the percentage of tumor cells was counted manually. On average, the range between the lowest and the highest estimate per sample was 6.3 categories. In 33% of estimates, the deviation from the gold standard was at least three categories. The mean absolute deviation was 2.0 categories (range between observers 1.5-3.1 categories). There was a significant difference between the observers (Po0.001). If 20% of tumor cells were considered the lower limit to detect a mutation, samples with an insufficient tumor cell percentage (o20%) would have been estimated to contain enough tumor cells in 27/72 (38%) observations, possibly causing false negative results. In conclusion, estimates of tumor cell percentages on H&E-stained slides are not accurate, which could result in misinterpretation of test results. Reliability could possibly be improved by using a training set with feedback.

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Section: Resultsmentioning

confidence: 99%

The estimation of tumor cell percentage for molecular testing by pathologists is not accurate

et al. 2014

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“…A heterogeneous distribution of EGFR mutation within the same tumor and between the primary tumor and its metastases has been demonstrated. 27 Whether this might be the reason for the discrepant results from the EGFR analyses in these cases is unknown.…”

Section: Discussionmentioning

confidence: 98%

High specificity but low sensitivity of mutation-specific antibodies against EGFR mutations in non-small-cell lung cancer

et al. 2014

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Determination of epidermal growth factor receptor (EGFR) mutations has a pivotal impact on treatment of non-small-cell lung cancer (NSCLC). A standardized test has not yet been approved. So far, Sanger DNA sequencing has been widely used. Its rather low sensitivity has led to the development of more sensitive methods including real-time PCR (RT-PCR). Immunohistochemistry with mutation-specific antibodies might be a promising detection method. We evaluated 210 samples with NSCLC from an unselected Caucasian population. Extracted DNA was analyzed for EGFR mutations by RT-PCR (Therascreen EGFR PCR kit, Qiagen, UK; reference method). For immunohistochemistry, antibodies against exon19 deletions (clone 6B6), exon21 mutations (clone 43B2) from Cell Signaling Technology (Boston, USA) and EGFR variantIII (clone 218C9) from Dako (Copenhagen, DK) were applied. Protein expression was evaluated, and staining score (multipum of intensity (graded 0-3) and percentages (0-100%) of stained tumor cells) was calculated. Positivity was defined as staining score 40. Specificity of exon19 antibody was 98.8% (95% confidence interval ¼ 95.9-99.9%) and of exon21 antibody 97.8% (95% confidence interval ¼ 94.4-99.4%). Sensitivity of exon19 antibody was 63.2% (95% confidence interval ¼ 38.4-83.7%) and of exon21 antibody was 80.0% (95% confidence interval ¼ 44.4-97.5%). Seven exon19 and four exon21 mutations were false negatives (immunohistochemistry negative, RT-PCR positive). Two exon19 and three exon21 mutations were false positive (immunohistochemistry positive, RT-PCR negative). One false positive exon21 mutation had staining score 300. The EGFR variantIII antibody showed no correlation to EGFR mutation status determined by RT-PCR or to EGFR immunohistochemistry. High specificity of the mutation-specific antibodies was demonstrated. However, sensitivity was low, especially for exon19 deletions, and thus these antibodies cannot yet be used as screening method for EGFR mutations in NSCLC. Refinement of sensitivity for the mutation-specific antibodies is warranted to improve molecular diagnosis using EGFR immunohistochemistry.

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“…For clinical analysis, TKIs resistance in a proportion of patients with EGFR mutation is always explained by the heterogeneity of EGFR mutation between PT and metastatic lesions (Park et al, 2009), or even between parts of PT (Sakurada et al, 2008). Several reasons for discordance of molecular biomarkers associated with EGFR mutation between PT and LNM may be attributable to the presence of intratumoral heterogeneity of EGFR mutations or to technical limitations of the methods used for the assessment of EGFR mutations or to changes in EGFR mutations during disease progression and metastasis.…”

Section: Discussionmentioning

confidence: 99%

Comparison of Epidermal Growth Factor Receptor Mutations between Primary Tumors and Lymph Nodes in Non-small Cell Lung Cancer: a Review and Meta-analysis of Published Data

Wang

Fang²,

Hou³

et al. 2014

Asian Pacific Journal of Cancer Prevention

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Background: Epidermal growth factor receptor (EGFR) mutations in non-small cell lung cancer (NSCLC) can predict the clinical response to tyrosine kinase inhibitor (TKI) therapy. However, EGFR mutations may be different in primary tumors (PT) and metastatic lymph nodes (MLN). The aim of this study was to compare EGFR mutations between PT and the corresponding MLN in NSCLC patients, and provide some guidelines for clinical treatment using TKI therapy. Materials and Methods: A systematic review and meta-analysis was performed with several research databases. Relative risk (RR) with the 95% confidence interval (CI) were used to investigate the EGFR mutation status between PT and the corresponding MLN. A random-effects model was used. Results: 9 publications involving 707 patients were included in the analysis. It was found that activation of EGFR mutations identified in PT and the corresponding MLN was 26.4% (187/707) and 19.9% (141/707), respectively. The overall discordance rate in our meta-analysis was 12.2% (86/707). The relative risk (RR) for EGFR mutation in PT relative to MLN was 1.33 (95%CI: 1.10-1.60; random-effects model). There was no significant heterogeneity between the studies (I 2 =5%, p=0.003). Conclusions: There exists a considerable degree of EGFR mutation discrepancy in NSCLC between PT and corresponding MLN, suggesting that tumor heterogeneity might arise at the molecular level during the process of metastasis.

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Discordance of Molecular Biomarkers Associated with Epidermal Growth Factor Receptor Pathway between Primary Tumors and Lymph Node Metastasis in Non-small Cell Lung Cancer

Abstract: A considerable proportion of NSCLC showed discrepancy in EGFR mutations between primary tumors and metastatic lymph nodes, suggesting tumor heterogeneity at the molecular level during the process of metastasis.

Cited by 136 publications

References 34 publications

The estimation of tumor cell percentage for molecular testing by pathologists is not accurate

The estimation of tumor cell percentage for molecular testing by pathologists is not accurate

High specificity but low sensitivity of mutation-specific antibodies against EGFR mutations in non-small-cell lung cancer

Comparison of Epidermal Growth Factor Receptor Mutations between Primary Tumors and Lymph Nodes in Non-small Cell Lung Cancer: a Review and Meta-analysis of Published Data

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