Grønhøj Larsen, C3; Gyldenløve, M1; Jensen, D H3; Therkildsen, M H2; Kiss, K2; Norrild, B4; Konge, L5; von Buchwald, C3
1 Dermatology and Allergy, Herlev and Gentofte Hospital, The Capital Region of Denmark2 Patologiafdelingen, Diagnostisk Center, Rigshospitalet, The Capital Region of Denmark3 unknown4 University of Copenhagen5 Copenhagen Academy for Medical Education and Simulation, The Capital Region of Denmark
a systematic review
Background:A significant proportion of squamous cell carcinomas of the oropharynx (OP-SCC) are related to human papillomavirus (HPV) infection and p16 overexpression. This subgroup proves better prognosis and survival but no evidence exists on the correlation between HPV and p16 overexpression based on diagnostic measures and definition of p16 overexpression. We evaluated means of p16 and HPV diagnostics, and quantified overexpression of p16 in HPV-positive and -negative OP-SCCs by mode of immunohistochemical staining of carcinoma cells.Methods:PubMed, Embase, and the Cochrane Library were searched from 1980 until October 2012. We applied the following inclusion criteria: a minimum of 20 cases of site-specific OP-SCCs, and HPV and p16 results present. Studies were categorised into three groups based on their definition of p16 overexpression: verbal definition, nuclear and cytoplasmatic staining between 5 and 69%, and 70% staining.Results:We identified 39 studies with available outcome data (n=3926): 22 studies (n=1980) used PCR, 6 studies (n=688) used ISH, and 11 studies (n=1258) used both PCR and ISH for HPV diagnostics. The methods showed similar HPV-positive results. Overall, 52.5% of the cases (n=2062) were HPV positive. As to p16 overexpression, 17 studies (n=1684) used a minimum of 5-69% staining, and 7 studies (n=764) used 70% staining. Fifteen studies (n=1478) referred to a verbal definition. Studies showed high heterogeneity in diagnostics of HPV and definition of p16. The correlation between HPV positivity and p16 overexpression proved best numerically in the group applying 70% staining for p16 overexpression. The group with verbal definitions had a significantly lower false-positive rate, but along with the group applying 5-69% staining showed a worse sensitivity compared with 70% staining.Conclusions:There are substantial differences in how studies diagnose HPV and define p16 overexpression. Numerically, p16 staining is better to predict the presence of HPV (i.e. larger sensitivity), when the cutoff is set at 70% of cytoplasmatic and nuclear staining.