Sensitivity and Specificity of Human Papillomavirus (HPV) 16 Early Antigen Serology for HPV-Driven Oropharyngeal Cancer: A Systematic Literature Review and Meta-Analysis

Abstract

Antibodies against HPV16 early proteins have been shown to be promising biomarkers for the identification of HPV-driven oropharyngeal cancer (HPV-OPC) among OPC cases in multiple studies. A systematic literature search was performed to identify original research articles comparing HPV early antigen serology with established reference methods to determine molecular HPV tumor status. Random-effects models were used to calculate summary estimates for sensitivity and specificity of HPV16 E2, E6 and E7 serology for HPV-OPC. Subgroup analyses were performed to explore heterogeneity across studies and describe variables associated with test performance. We identified n = 23 studies meeting all eligibility criteria and included these in the meta-analysis. E6 serology showed the best performance with pooled sensitivity and specificity estimates of 83.1% (95% confidence interval (CI) 72.5-90.2%) and 94.6% (95% CI 89.0-97.4%), respectively, while E2 and E7 serological assays were highly specific (E2: 92.5% (95% CI 79.1-97.6%); E7: 88.5% (95% CI 77.9-94.4%)) but moderately sensitive (E2: 67.8% (95% CI 58.9-75.6%); E7: 67.0% (95% CI 63.2-70.6%)). Subgroup analyses revealed increased pooled sensitivity for bacterially (89.9% (95% CI 84.5-93.6%)) vs. in vitro expressed E6 antigen (55.3% (95% CI 41.0-68.7%)), while both showed high specificity (95.2% (95% CI 93.0-96.7%) and 91.1% (95% CI 46.6-99.2%), respectively). Pooled specificity estimates for HPV16 E2, E6 and E7 serology were significantly lower in studies utilizing HPV DNA PCR as the only molecular reference method compared to those using a combination of any two reference methods (HPV DNA, RNA, in situ hybridization (ISH), p16 immunohistochemistry (IHC)), or histopathological reference methods (ISH or p16 IHC) as stand-alone marker. In conclusion, HPV16 E6 seropositivity is a highly sensitive and specific biomarker for HPV-OPC. However, its performance differs between serological assays and depends on molecular reference methods.

Keywords: HPV; antibodies; meta-analysis; oropharyngeal cancer; sensitivity; serology; specificity; systematic review.

Figure 1

PRISMA flow diagram of study selection process [17].

Figure 2

Bar plot of summary estimates of sensitivity (red) and specificity (blue) for HPV16 early protein serology (E2, E6 and E7) in comparison with molecular HPV tumor status. Whiskers represent 95% confidence intervals. Summary estimates were calculated by meta-analyses using random effects models.

Figure 3

Forest plots of study-specific sensitivity and specificity estimates and summary estimates for HPV16 E6 serology in comparison with molecular HPV tumor status. Pooled estimates were calculated by univariate analysis of log-transformed proportions using a random effects model. Sensitivity of E6 with subgroup summary estimates (I² = 94.4% (92.6–95.8%)) was stratified by (a) protein expression system and (c) reference method. Specificity of E6 with subgroup summary estimates (I² = 85.5% (77.8–90.5%)) was stratified by (b) protein expression system and (d) reference method. TP: true positive; FN: false negative; TN: true negative; FP: false positive; CI: confidence intervals; ISH: in situ hybridization; p16: p16 immunohistochemistry; DNA only: HPV DNA PCR.

Figure 4

Forest plots of study-specific sensitivity and specificity estimates and summary estimates for HPV16 E7 serology in comparison with molecular HPV tumor status. Pooled estimates were calculated by univariate analysis of log-transformed proportions using a random effects model. Sensitivity of E7 with subgroup summary estimates (I² = 37.1% (0.0–64.8%)) was stratified by (a) protein expression system and (c) reference method. Specificity of E7 with subgroup summary estimates (I² = 90.4% (85.7–93.6%)) was stratified by (b) protein expression system and (d) reference method. TP: true positive; FN: false negative; TN: true negative; FP: false positive; CI: confidence intervals; ISH: in situ hybridization; p16: p16 immunohistochemistry; DNA only: HPV DNA PCR.

Figure 5

Forest plots of study-specific sensitivity and specificity estimates and summary estimates of HPV16 E2 serology in comparison with molecular HPV tumor status. Pooled estimates were calculated by univariate analysis of log-transformed proportions using a random effects model. Sensitivity of E2 with subgroup summary estimates (I² = 90.6% (86.3–93.5%)) was stratified by (a) E2 antigens and (c) reference method. Specificity of E2 with subgroup summary estimates (I² = 94.2% (91.6–96.0%)) was stratified by (b) protein variant and (d) reference method. TP: true positive; FN: false negative; TN: true negative; FP: false positive; CI: confidence intervals; ISH: in situ hybridization; p16: p16 immunohistochemistry; DNA only: HPV DNA PCR.

Figure 6

Stacked bar charts of risk of bias assessment according to QUADAS-2 [21]. Study quality expressed as percentage of studies showing low (green), unclear (blue) and high (red) potential of bias in four domains.