PAX1 methylation as a robust predictor: developing and validating a nomogram for assessing endocervical curettage (ECC) necessity in human papillomavirus16/18-positive women undergoing colposcopy

Abstract

Objective: The major challenge in routine endocervical curettage (ECC) among Human Papillomavirus (HPV) 16/18-positive patients is that only a small fraction benefit. Nevertheless, current reported models often overestimate the validity and necessity of ECC, making it difficult to improve benefits for patients. This research hypothesized that assessing paired boxed gene 1 methylation levels (PAX1^m) and clinical characteristics could enhance the predictive accuracy of detecting additional high-grade squamous intraepithelial lesions or worse (HSIL +) through ECC that were not identified by colposcopy-directed biopsy (CDB).

Methods: Data from 134 women with HPV16/18 positivity undergoing CDB and ECC between April 2018 and April 2022 were collected and analyzed. Quantitative methylation-specific polymerase chain reaction (qMSP) was utilized to measure PAX1^m, expressed as ΔCp. Univariate and multivariate regression analyses were conducted to screen variables and select predictive factors. A nomogram was constructed using multivariate logistic regression to predict additional HSIL + detected by ECC. The discrimination, calibration, and clinical utility of the nomogram were evaluated using receiver operating characteristic curves (ROC) and the calibration plot.

Results: Age (odds ratio [OR], 5.654; 95% confidence interval [CI], 1.131-37.700), cytology (OR, 24.978; 95% CI, 3.085-540.236), and PAX1 methylation levels by grade (PAX1^m grade) (OR, 7.801; 95% CI, 1.548-44.828) were independent predictive factors for additional detection of HSIL + by ECC. In HPV16/18-positive women, the likelihood of additional detection of HSIL + through ECC increased with the severity of cytological abnormalities, peaking at 43.8% for high-grade cytological lesions. Moreover, when cytological findings indicated low-grade lesions, PAX1 methylation levels were positively correlated with the additional detection of HSIL + by ECC (P value < 0.001). A nomogram prediction model was developed (area under curve (AUC) = 0.946; 95% CI, 0.901-0.991), demonstrating high sensitivity (90.9%) and specificity (90.5%) at the optimal cutoff point of 107. Calibration analysis confirmed the model's strong agreement between predicted and observed probabilities.

Conclusion: The clinical nomogram presented promising predictive performance for the additional detection of HSIL + through ECC among women with HPV16/18 infection. PAX1 methylation level could serve as a valuable tool in guiding individualized clinical decisions regarding ECC for patients with HPV 16/18 infection, particularly in cases of low-grade cytological findings.

Keywords: DNA methylation; Endocervical curettage; Human papillomavirus; Nomogram prediction model; PAX1.

Fig. 1

Flowchart of patients. CDB, colposcopically directed biopsy; ECC, endocervical curettage; PAX1, paired boxed gene 1; HPV16/18, human papillomavirus 16/18; LSIL, low-grade squamous intraepithelial lesion; HSIL + , high-grade squamous intraepithelial lesion or worse; ECC ≤ CDB, cases with pathological findings detected by ECC were less severe than or equal to CDB; ECC (H +) > CDB, cases with the pathological findings detected by ECC were more severe than CDB, with ECC detecting HSIL and worse; ECC (L) > CDB, cases in which pathological findings identified by ECC were more severe than CDB, with ECC detecting LSIL, PAX1 methylation test time apart from biopsy time greater than 2 weeks was defined as too far

Fig. 2

ROC curves of different models predicting ECC (H +) > CDB for women with positive HPV16/18. ROC: receiver operating characteristic; AUC: area under curve; CI: confidence interval; PAX1^m Grade: PAX1 methylation level by grade

Fig. 3

Nomogram predicting ECC (H +) > CDB for women with positive HPV16/18

Fig. 4

Calibration plots showing the observed frequency and predicted probability for the predictive model (A) The univariate mode of PAX1^m Grade. (B) The multivariate mode