Testing for methylated PCDH10 or WT1 is superior to the HPV test in detecting severe neoplasms (CIN3 or greater) in the triage of ASC-US smear results.

OBJECTIVE

Management of equivocal Papanicolaou smear result remains to be challenging even with the aid of human papillomavirus test. Recently, 3 novel methylation-silenced genes, PAX1, WT1, and PCDH10, have been found to be specifically associated with cervical cancer. We compared the performances of methylation test of these genes with human papillomavirus tests in triage of equivocal Papanicolaou smear result.

STUDY DESIGN

Two hundred twenty-two women with Papanicolaou smear results of atypical cells of undetermined significance nested to a multicenter, nation-wide cohort (the T1899 cohort) were studied. Status of cervical neoplasm was diagnosed with colposcopic biopsy. Status of gene methylation was determined by methylation-specific polymerase chain reaction. High-risk human papillomavirus DNA was detected by polymerase chain reaction-reverse line blot hybridization and Hybrid Capture 2.

RESULTS

Cervical intraepithelial neoplasm 1, cervical intraepithelial neoplasm 2, cervical intraepithelial neoplasm 3, carcinoma in situ, carcinoma, and normal cervix were diagnosed in 58, 17, 14, 10, 1, and 120 women, respectively. Methylation of PCDH10, WT1, and PAX1 was highly associated with the severity of cervical neoplasm (P < 10⁻⁹, < 10⁻⁷, and < 10⁻⁵, respectively). In comparison with a negative test result, the odds ratio (95% confidence intervals) for cervical intraepithelial neoplasm 3 or more severe neoplasms for women tested positive for methylation of these 3 genes were 26.4 (9.0-77.3), 18.1 (6.9-47.2), and 10.3 (4.1-25.9), respectively; whereas those positive for human papillomavirus polymerase chain reaction and Hybrid Capture 2 were 10.5 (3.5-31.9) and 5.6 (2.3-21.4). In triage for atypical cells of undetermined significance, each methylation test had less colposcopy referral and false-positive rates, but higher false-negative rate than the human papillomavirus tests. With a combination test of PCDH10 or WT1 methylation, a comparable false-negative rate (P = .62) but much less false-positive rate (P = .002) and colposcopy referral rate (P < 10⁻⁶) were achieved.

CONCLUSION

In triage of atypical cells of undetermined significance Papanicolaou smear results, methylation test of WT1 and PCDH10 is superior to human papillomavirus test in this multicenter cohort. Comparing to current human papillomavirus triage, the new test has only one third of false positivity and half of colposcopy referral, with no compromise of the sensitivity in diagnosis of cervical intraepithelial neoplasm 3 or more severe neoplasms.