A Sensitive and Simplified Classifier of Cervical Lesions Based on a Methylation-Specific PCR Assay: A Chinese Cohort Study

OBJECTIVE: The aim of this study is to assess the diagnostic and screening performance of a standardized methylation-specific real-time PCR assay targeting SOX1 and PAX1 genes for cervical cancer in a Chinese cohort. METHODS: Genomic DNA was extracted from cervical exfoliated cells and converted by sodium bisulfite and then analyzed by qMSP assay. Ct values were collected for PAX1 and SOX1 as target genes and β-actin as an endogenous reference gene. The samples included 295 cervicitis, 111 LSIL (low-grade squamous intraepithelial lesion), 51 HSIL (high-grade squamous intraepithelial lesion) and 30 cervical cancer. RESULTS: The Ct values decreased with the progression of cervical cancer from cervicitis, through LSIL and HSIL to cancer. The difference in Ct values between cytological grades was highly significant (p≤0.01) between grades either for PAX1 or for SOX1 except the difference between cervicitis and LSIL of SOX1. With the Ct cut-off values of PAX1 gene and SOX1 gene 38.6 and 38 and with the PAX1/SOX1 in combination, the positive rate of methylation in invasive cancer tissues was 100%, in contrast to 11.5% (95% CI: 8.67%–14.33%) in cervicitis tissues, 45.1% (95% CI: 40.68%–49.52%) in LSIL tissues, and 68.5% (95% CI: 64.37%–72.63%) in HSIL tissues. The specificity and sensitivity of differentiating tumors from cervicitis were 0.957 (95% CI: 0.939–0.975) and 1.00, respectively. The specificity and sensitivity of differentiation between cervicitis+LSIL and HSIL+cervical cancer were 0.881 (95% CI: 0.852–0.91) and 0.748 (95% CI: 0.709–0.787), respectively. CONCLUSION: PAX1/SOX1 methylation could be translated into clinical practice for cervical neoplasia detection.