Combined detection of SHOX2 and PTGER4 methylation with serum marker CYFRA21-1 for improved diagnosis of malignant pleural mesothelioma

Aims To investigate the performance of a combined biomarker approach using the methylation status of the short stature homeobox 2 ( SHOX2 ) and prostaglandin E2 receptor EP4 ( PTGER4 ) genes, along with the serum levels of CYFRA21-1, for differential diganosis of malignant pleural mesothelioma (MPM) from benign reactive mesothelial hyperplasia (RMH). Methods We analysed 48 MPM tissue or pleural effusion cell block specimens and 42 cases with RMH. Real-time quantitative methylation-specific PCR was used to examine the methylation status of SHOX2 , PTGER4 , ras association domain family 1 isoform A, septin 9 gene and homeobox gene A9 genes. Additionally, we employed electrochemiluminescence immunoassay to measure nine serum tumour markers commonly used in pan-cancer screening tests. Results The receiver operating curve indicated that SHOX2 , PTGER4 gene methylation and serum biomarker CYFRA21-1 exhibited good diagnostic performance in identifying MPM, with area under curves (AUCs) of 0.761, 0.904 and 0.847, respectively. The combination of SHOX2 , PTGER4 methylation and CYFRA21-1 yielded an AUC value of 0.972. The diagnostic sensitivity and specificity of this panel in differentiating MPM from RMH were 91.3% (42/46) and 97.6% (41/42), respectively. Both tissue and cell block specimens can be used in the diagnostic process. Furthermore, elevated CYFRA21-1 levels were associated with poor prognosis (p<0.05). Hypermethylation level of PTGER4 may indicate an unfavourable prognosis of MPM, but the difference was not statistically significant. Conclusions The combined detection of SHOX2 and PTGER4 methylation alongside serum CYFRA21-1 level significantly enhances the diagnosis of MPM. Additionally, CYFRA21-1 can serve as a prognostic indicator for MPM.