Analysis of PAX8 immunohistochemistry in lung cancers: a meta-analysis

Prognostic value of PAX8 in small cell lung cancer

Objectives

Small cell lung cancer (SCLC) shows poor prognosis since it metastasizes widely at early stage. Paired box gene (PAX) 8 is a transcriptional factor of PAX family, of which the expression in lung cancer is a controversial issue, and its prognostic value of PAX8 in SCLC is still unclear.

Materials and methods

Overall, 184 subjects who were pathologically diagnosed with SCLC were enrolled in the study. Immunohistochemical analysis of PAX8 and Ki-67 were performed. The correlations between PAX8 expression and clinical features or Ki-67 index were further analyzed. Subsequently, an analysis of the association between PAX8, stage, Ki-67 status, and overall survival (OS) were performed in 169 subjects with follow-up information.

Results

PAX8 was positive in 53.8% (99/184) SCLC specimens. The positive rate is significantly higher in extensive-stage specimens (61.0%) than in limited-stage specimens (45.24%). PAX8 expression is positively correlated with Ki-67 index (P = 0.001) while negatively correlated with OS (HR = 3.725, 95% CI 1.943-7.139, P＜0.001). In combination groups, the PAX8 negative and limited stage group had the most promising OS.

Conclusion

PAX8 expression rate in SCLC specimens is not low. It has prognostic value in small cell lung cancer.

Significance analysis of PAX8 expression in endometrial carcinoma

To analyze the expression and prognostic value of paired-box 8 (PAX8) expression in uterine corpus endometrial carcinoma (UCEC) by bioinformatics. The expression of PAX8 gene in UCEC was analyzed by R language and immunohistochemistry. The correlation between PAX8 expression and clinicopathological features was analyzed by R language. The prognostic factors was analyzed by univariate/multivariate regression. The survival curve of patients was analyzed by Kaplan-Meier Plotter (K-M Plotter). The diagnostic value of PAX8 in UCEC was analyzed by receiver operating characteristic curve, and the relationship between PAX8 expression and methylation was analyzed by Ualcan. The relationship between methylation and prognosis was analyzed by MethSurv database. The expression of PAX8 in cancer tissues was significantly higher than that in normal tissues. The expression of PAX8 was related to clinical stage, age, histological type, histologic grade, tumor invasion and disease-specific survival event. Univariate/multivariate regression analysis showed that clinical stage, tumor invasion, and PAX8 expression were the influence factors of overall survival (OS), while histologic grade and PAX8 expression were the influence factors of disease-specific survival, and patients with low expression had a longer OS. The area under the curve of receiver operating characteristic curve was 0.81 for PAX8 diagnosis of UCEC. PAX8 was hypomethylated in cancer tissue, and patients with hypermethylated PAX8 had a longer OS. The high expression of PAX8 induced by hypomethylation may play an important role in the occurrence and prognosis of UCEC.

Initial panel of immunocytochemical markers for identification of primary carcinoma site for effusions and peritoneal washings from women

INTRODUCTION

In women, most malignant effusions are from breast and ovary primary carcinomas that have metastasized to body cavity fluids (pleural, peritoneal and pericardial). When carcinoma is diagnosed in effusions, it is not possible to identify its site of origin solely by cytology (morphology); therefore, immunocytochemistry is used as a complementary method. There are no immunocytochemical markers with 100% sensitivity and specificity for identifying carcinoma primary site. The markers most used are TTF-1 for the lung, GATA-3 for the breast, and PAX-8 for the ovary. The aim of this study was to evaluate the sensitivity and specificity of a panel including these markers for detecting the primary site of carcinoma in effusions.

METHODS

Samples of pleural, pericardial, and peritoneal effusions and peritoneal washings with carcinoma of known primary site from women (n = 60) and men (n = 18) were prepared by using the cell block method, and immunocytochemistry was performed to evaluate the expression of primary site markers (TTF-1, PAX-8, and GATA-3).

RESULTS

In women, the breast was the most frequent primary site of metastatic carcinoma to both pleural and pericardial cavities, followed by the lung, whereas the ovary was the most frequent primary site of carcinoma within peritoneal effusions and washings, followed by the gastrointestinal tract (stomach or intestine). The expected profiles for carcinomas of the most common primary sites were: breast (GATA-3 (+), PAX-8 (-), TTF-1 (-)), ovary (PAX-8 (+), GATA-3 (-), TTF-1 (-)), lung (TTF-1 (+), PAX-8 (-) GATA-3 (-)) and gastrointestinal tract (PAX-8 (-), GATA-3 (-), TTF-1 (-)). These were observed in 88.23% (45/51) of women's samples with carcinoma from these primary sites. By using TTF-1 as the sole primary site marker, 6.25% of carcinomas of primary site other than the lung would have been misdiagnosed.

CONCLUSION

An initial panel of markers including GATA-3, PAX-8, and TTF-1 allows, with high sensitivity and specificity, the identification or exclusion of frequent primary sites of carcinoma in effusions from women. Our results highlight the importance of using a panel of markers to avoid misidentification of the primary site of tumor.

Immunocytochemistry of effusions: Processing and commonly used immunomarkers

Definitive cytopathological interpretation of some of the effusion fluids may not be possible based on cytomorphological evaluation alone. As discussed in other reviews, this is due to various reasons specifically applicable to effusion fluids including remarkably wide morphologic spectrum of reactive mesothelial cells overlapping with some well to moderately differentiated metastatic carcinoma. The challenge is subject to various factors including level of interpreter training or experience, institutional demographics (such as type of prevalent diseases, predominant sex and age group), technical advances in ancillary support, and expertise in cytopreparatory processing. In such cases immunohistochemistry performed on cell-block sections is simple objective adjunct with or without other ancillary techniques. Ongoing increase in number of immunomarkers along with rabbit monoclonal antibodies with relatively higher affinity is further refining this field. SCIP (subtractive coordinate immunoreactivity pattern) approach, discussed as separate dedicated review article, facilitates refined interpretation of immunoreactivity pattern in coordinate manner on various serial sections of cell-blocks. However, many variables such as delay after specimen collection, specimen processing related factors including fixation and storage; ambient conditions under which paraffin blocks are archived (for retrospective testing); antigen retrieval method; duration of antigen retrieval step; antibody clone and dilution; and antibody application time are common with application of immunohistochemistry in other areas. This review is dedicated to highlight technical aspects including processing of effusion specimens for optimum immunocytochemical evaluation along with commonly used immunomarkers in effusion cytopathology. This review focuses on the technical and general information about various immunomarkers.

Application of Immunohistochemistry in Papillary Thyroid Carcinoma

Immunohistochemistry (IHC) is an economic and precise method to localize the presence of specific protein at cellular level in tissue. Although many papillary thyroid carcinomas do not require IHC to render a diagnosis, there are certain scenarios in which IHC are important. The major diagnostic applications of IHC include confirmation of papillary thyroid carcinoma in sites other than the thyroid, distinguish papillary thyroid carcinoma from other primary thyroid neoplasms in thyroid, and identify papillary thyroid carcinoma from secondary tumors to the thyroid. At research level, IHC could help identify prognostic information, identify underlying genetic alterations, and predict response to treatment in papillary thyroid carcinoma. The understanding of principle and recent advances in IHC will improve the diagnosis and management of patients with thyroid lesions including papillary thyroid carcinoma.