Associations between oral HPV16 infection and cytopathology: evaluation of an oropharyngeal "pap-test equivalent" in high-risk populations

Abstract

Human papillomavirus (HPV) is responsible for the rising incidence of oropharyngeal squamous cell cancers (OSCC) in the United States, and yet, no screening strategies have been evaluated. Secondary prevention by means of HPV detection and cervical cytology has led to a decline in cervical cancer incidence in the United States. Here, we explored an analogous strategy by evaluating associations between HPV16 infection, cytopathology, and histopathology in two populations at elevated risk for OSCCs. In the first, a cross-sectional study population (PAP1), cytology specimens were collected by means of brush biopsy from patients presenting with oropharyngeal abnormalities. In the second (PAP2), a nested case-control study, bilateral tonsillar cytology samples were collected at 12-month intervals from HIV-infected individuals. The presence of cytopathologic abnormality in HPV16-positive tonsil brush biopsies (cases) was compared with HPV16-negative samples (controls) matched on age and gender. HPV16 was detected in samples by consensus primer PCR and/or type-specific PCR. Univariate logistic regression was used to evaluate associations. In PAP1, HPV16 alone (OR: 6.1, 95% CI: 1.6-22.7) or in combination with abnormal cytology (OR: 20, 95% CI: 4.2-95.4) was associated with OSCC. In PAP2, 4.7% (72 of 1,524) of tonsillar cytology specimens from HIV-infected individuals without oropharyngeal abnormalities were HPV16 positive. Tonsillar HPV16 infection was not associated with atypical squamous cells of unknown significance (ASCUS), the only cytologic abnormality identified. Therefore, HPV16 was associated with OSCCs among individuals with accessible oropharyngeal lesions but not with cytologic evidence of dysplasia among high-risk individuals without such lesions. An oropharyngeal Pap-test equivalent may not be feasible, likely due to limitations in sampling the relevant tonsillar crypt epithelium.

Figure 1

Cytological appearance of normal-appearing superficial squamous cells (left panel; magnification x 200, Papanicolaou stain) and ASCUS of a tonsillar cytology sample (right panel; magnification x 400, Papanicolaou stain). Note the cell in the center with slight nuclear enlargement and mild nuclear hyperchromasia relative to the surrounding normal squamous cells.

Figure 2

HPV16 infection status in HIV-infected individuals over time. Oral rinses were collected from subjects at visits 1 (baseline), 2 (6-months), 3 (12-months), 4 (18-months) and 5 (24-months). Tonsillar samples were collected at visits 1, 3 and 5. Oral rinse samples and tonsillar cytology samples were evaluated for the presence of HPV16. Figure 2A shows individuals who were present for all three visits and had at least one detectable tonsillar HPV16 infection. Shaded circles are tonsillar samples which are HPV16-positive. Unshaded circles are HPV16-negative tonsillar samples. In figure 2B, individuals who had an oral HPV16 infection detected during at least one visit are depicted. Shaded circles are oral rinse samples which are HPV16-positive. Open circles indicate HPV16-negative oral rinse samples. Horizontal bar indicates a concomitant tonsillar HPV16 infection. The absence of circle signifies that an individuals did not provide oral rinse sample, was lost to follow-up or sample was unevaluable at a specific visit.

Figure 2

HPV16 infection status in HIV-infected individuals over time. Oral rinses were collected from subjects at visits 1 (baseline), 2 (6-months), 3 (12-months), 4 (18-months) and 5 (24-months). Tonsillar samples were collected at visits 1, 3 and 5. Oral rinse samples and tonsillar cytology samples were evaluated for the presence of HPV16. Figure 2A shows individuals who were present for all three visits and had at least one detectable tonsillar HPV16 infection. Shaded circles are tonsillar samples which are HPV16-positive. Unshaded circles are HPV16-negative tonsillar samples. In figure 2B, individuals who had an oral HPV16 infection detected during at least one visit are depicted. Shaded circles are oral rinse samples which are HPV16-positive. Open circles indicate HPV16-negative oral rinse samples. Horizontal bar indicates a concomitant tonsillar HPV16 infection. The absence of circle signifies that an individuals did not provide oral rinse sample, was lost to follow-up or sample was unevaluable at a specific visit.