Type-Specific Viral Load and Physical State of HPV Type 16, 18, and 58 as Diagnostic Biomarkers for High-Grade Squamous Intraepithelial Lesions or Cervical Cancer

Abstract

Purpose: High rate of false-positive tests is a major obstacle to use human papillomavirus (HPV) detection as a diagnostic tool for high-grade squamous intraepithelial lesions or cervical cancer (HSIL+). We investigated whether type-specific viral load or physical state of HPV 16, 18, and 58 are useful biomarkers for HSIL+.

Materials and methods: Type-specific viral loads of E6 and E2 genes in cervical cells from 240, 83, and 79 HPV 16-, 18-, and 58-infected women, respectively, were determined using real-time polymerase chain reaction. Viral loads were normalized to cellular DNA (copy/cell). Total and integrated viral loads and physical state were compared between HSIL+ and controls, and diagnostic value was determined using receiver operating characteristic analysis.

Results: Viral loads of HPV 16, 18, and 58 were significantly different in lesions in the same pathologic grade. High type-specific total viral loads were significantly associated with HSIL+ (odds ratio [OR], 14.065, 39.472, and 7.103 for HPV 16, 18, and 58, respectively). High integrated viral load was related to HSIL+ in women with HPV 16 (OR, 8.242), and integrated state was associated with HSIL+ in women with HPV 18 (OR, 9.443). Type-specific total viral load was significantly associated with HSIL+ (area under curve, 0.914, 0.937, and 0.971 for HPV 16, 18, and 58, respectively), indicating an excellent performance in detecting HSIL+.

Conclusion: Type-specific total viral load may be a powerful diagnostic marker for HSIL+ in HPV 16-, 18-, and 58-infected HSIL+ lesions. If demonstrated in all other high-risk HPV types, this method can lead to a paradigm shift in the strategy of equivocal cytologic abnormalities.

Keywords: Cervical cancer; High-grade squamous intraepithelial lesions; Human papillomavirus; Viral load.

Fig. 1.

Flowchart of the study subjects. Pap, Papanicolaou; HPV, human papillomavirus; HSIL, high-grade squamous intraepithelial lesions; HSIL+, high-grade squamous intraepithelial lesions or cervical cancer.

Fig. 2.

Type-specific normalized total viral load of human papillomavirus (HPV) 16, 18, and 58 in patients with cervical lesions at the same pathologic grade. Box plots show median and interquartile range. Controls include patients without pathologic abnormalities or with low-grade squamous intraepithelial lesions. p-values were evaluated using Kruskal-Wallis tests. HSIL, high-grade squamous intraepithelial lesions; ICC, invasive cervical cancer.

Fig. 3.

Receiver operating characteristic curve analysis of human papillomavirus (HPV) 16, 18, and 58 for the detection of high-grade squamous intraepithelial lesions or cervical cancer by type-specific total and integrated viral load. AUC, area under the curve.