Abstract
This case series examines HPV seropositivity and antibody levels in a cohort of older men who have sex with men.
Oropharyngeal cancer (OPC) is rare and, in some countries, more than 70% of all cases are caused by human papillomavirus (HPV).1 The type HPV16 accounts for more than 85% of all cases of HPV–associated oropharyngeal cancer (HPV-OPC).1 Antibodies to the HPV16 E6 oncoprotein are biomarkers for determining the HPV status of OPC cases, with reported sensitivities of around 90% and specificities higher than 95%.2 Antibodies can be detected more than 10 years prior to OPC diagnosis.1,3 However, their positive predictive value for HPV-OPC is low, at approximately 1% per year.3,4 Most patients with HPV-OPC also have antibodies to other viral regulatory and oncoproteins (E1, E2, E7)1,2,3 and have higher antibody levels than seropositive individuals who do not develop cancer.1,3 Currently, there is no consensus on HPV-OPC screening,4 but including these other variables may improve the specificity of HPV-OPC prediction. We examined HPV16 E6, E7, E1, and E2 seropositivity and antibody levels in a cohort of older men who have sex with men (MSM).
Methods
The Study of Prevention of Anal Cancer (SPANC) was a cohort study of MSM 35 years and older in Sydney, Australia, investigating the natural history of anal HPV and associated diseases.5 Men were enrolled from 2010 to 2015. At baseline and 3 annual follow-up visits, anal swabs were taken for cytology and anal HPV DNA detection, and high-resolution anoscopy was performed to detect anal squamous intraepithelial lesions. A blood sample was taken for testing by multiplex HPV serology.6 Men who were HPV16 E6 seropositive at baseline had samples from all study visits tested and were contacted for clinical follow-up. The SPANC study had ethics approval from St Vincent’s Hospital, Sydney, Australia (HREC/09/SVH/168), and all study participants provided written consent. Additional approval was obtained to recontact the men with positive baseline serology.
Results
A total of 617 men were enrolled (220 [35.7%] HIV-positive; median age, 49 years), and 603 men had serology results. Of these, 13 had HPV16 E6 antibodies at baseline. One man was HIV positive. One man had antibodies to all 4 HPV16 early antigens (ID1), and 2 men had additional antibodies to HPV16 E2 or E7 (ID2 and ID3). These 3 men were among the 4 with the highest HPV16 E6 antibody levels (Table).
Table. Human Papillomavirus (HPV) Responses in 13 Men Who Were HPV16 E6 Seropositive at Baseline From the Study of Prevention of Anal Cancera.
| Patient No./Age, y | Anal | HPV DNA | HPV16 serology | HPV16 MFI (antigen)b | Persistence of seropositivity, mo (antigen) | Follow-up status | |
|---|---|---|---|---|---|---|---|
| Histology | Cytology | ||||||
| ID1/52 | LSIL | LSIL | 45 | E6, E1, E2, E7 | 9446 (E6), 666 (E1), 13810 (E2), 11314 (E7) | NA | OPC (deceased) |
| ID2/47 | HSIL-AIN2c | PHSIL | 56, 59 | E6, E2 | 4461 (E6), 785 (E2) | 24 (E6), 10 (E2) | OPC |
| ID3/45 | NA | Negative | Negative | E6, E7 | 4222 (E6), 2663 (E7) | 47 (E6), 47 (E7) | NA |
| ID4/56 | LSIL | HSIL-AIN3 | 16, 45 | E6 | 7421 (E6) | 38 (E6) | NAd |
| ID5/35 | HSIL-AIN3 | PHSIL | 18, 35, 51, 59 | E6 | 1767 (E6) | 12 (E6) | NA |
| ID6/45 | HSIL-AIN3 | HSIL-AIN3 | 33 | E6 | 1299 (E6) | 34 (E6) | NA |
| ID7/64 | LSIL | LSIL | Negative | E6 | 1664 (E6) | 20 (E6) | NA |
| ID8/56e | HSIL-AIN3 | PINV | 45 | E6 | 1039 (E6) | NA | NA |
| ID9/58 | LSIL | HSIL-AIN3 | 16, 51 | E6 | 824 (E6) | 13 (E6) | NA |
| ID10/49 | HSIL-AIN3 | Unsatisfactory | 16, 31, 51, 68 | E6, E1 | 821 (E6), 443 (E1) | NA | NA |
| ID11/65 | LSIL | PHSIL | 33, 58 | E6 | 2413 (E6) | 24 (E6) | Lost to follow-up |
| ID12/38 | HSIL-AIN3 | Unsatisfactory | 16, 39, 52, 59 | NAf | 811 (E6) | NA | Lost to follow-up |
| ID13/74 | Negative | PLSIL | 16 | NAf | 624 (E6) | NA | Refused follow-up |
Abbreviations: AIN, anal intraepithelial neoplasia; HSIL, high-grade squamous intraepithelial lesion; LSIL, low-grade squamous intraepithelial lesion; MFI, median fluorescence intensity; NA, not applicable, ie, not persistently seropositive throughout follow-up; OPC, oropharyngeal cancer; PHSIL, possible high-grade squamous intraepithelial lesion; PINV, possible invasion; PLSIL, possible low-grade squamous intraepithelial lesion.
Age (median, 52 years), anal histology, anal cytology, and HPV DNA (types positive) were assessed at baseline; HPV16 serology (antigens positive) assessed at last follow-up visit; HPV16 MFI indicates highest level during follow-up.
Standard MFI cutoffs were applied (ie, HPV16 E6 [484 MFI], E7 [548 MFI], E1 [200 MFI], E2 [679 MFI]).
Immunohistochemistry results positive for p16.
History of throat clearing and recurrent generalized sore throats.
HIV positive.
Seroreverted during follow-up (using the seropositivity cutpoint of 484 MFI units established for anal cancer).
Study participant ID1 died in 2014. He was diagnosed with tonsillar cancer in 2012, enrolled in SPANC in 2013, and was diagnosed with metastatic lung cancer (from his primary tonsillar cancer) in 2014. The remaining 12 individuals were invited for a head and neck examination and a positron emission tomography/computed tomography scan. A total of 9 men consented; 1 refused and 2 were lost to follow-up. One man (ID2) was diagnosed with asymptomatic p16-positive base-of-tongue cancer (T1 N1) and was treated with transoral robotic oropharyngectomy and neck dissection. The other 7 had no symptoms, except 1 participant with a history of throat clearing and recurrent generalized sore throats (ID4). All individuals were scheduled for follow-up visits every 6 months and annual positron emission tomography/computed tomography to account for the diagnostic lead time of HPV16 E6 serology.
Discussion
This case series informs the feasibility of HPV-OPC screening using HPV serology. Based on published estimates, approximately 1 in 10 seropositive men of this age group will present with HPV-OPC within 10 years,3,4 which is consistent with the present findings. These results also suggest that incorporating additional early antibodies, antibody levels, and age in screening algorithms may improve the utility of HPV serology for OPC prediction. The main limitation of the present study is its small sample size, and the results require replication in well-designed and sufficiently powered studies.
To our knowledge, this is the first report of a prospectively identified early HPV-OPC case by HPV serology. The early diagnosis of a clinically inapparent, small tumor will almost certainly be highly beneficial for this patient’s long-term survival. Human papillomavirus serology, as a tool to identify a population at the highest risk for development of HPV-OPC, warrants further evaluation.
References
- 1.Kreimer AR, Ferreiro-Iglesias A, Nygard M, et al. . Timing of HPV16-E6 antibody seroconversion before OPSCC: findings from the HPVC3 consortium. Ann Oncol. 2019;30(8):1335-1343. doi: 10.1093/annonc/mdz138 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Holzinger D, Wichmann G, Baboci L, et al. . Sensitivity and specificity of antibodies against HPV16 E6 and other early proteins for the detection of HPV16-driven oropharyngeal squamous cell carcinoma. Int J Cancer. 2017;140(12):2748-2757. doi: 10.1002/ijc.30697 [DOI] [PubMed] [Google Scholar]
- 3.Kreimer AR, Johansson M, Yanik EL, et al. . Kinetics of the human papillomavirus type 16 E6 antibody response prior to oropharyngeal cancer. J Natl Cancer Inst. 2017;109(8). doi: 10.1093/jnci/djx005 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Kreimer AR, Shiels MS, Fakhry C, et al. . Screening for human papillomavirus-driven oropharyngeal cancer: considerations for feasibility and strategies for research. Cancer. 2018;124(9):1859-1866. doi: 10.1002/cncr.31256 [DOI] [PubMed] [Google Scholar]
- 5.Poynten IM, Waterboer T, Jin F, et al. . Human papillomavirus seroprevalence and association with anal HPV infection and squamous intraepithelial lesions in Australian gay and bisexual men. Cancer Epidemiol Biomarkers Prev. 2018;27(7):768-775. doi: 10.1158/1055-9965.EPI-17-0694 [DOI] [PubMed] [Google Scholar]
- 6.Waterboer T, Sehr P, Michael KM, et al. . Multiplex human papillomavirus serology based on in situ-purified glutathione s-transferase fusion proteins. Clin Chem. 2005;51(10):1845-1853. doi: 10.1373/clinchem.2005.052381 [DOI] [PubMed] [Google Scholar]