Evaluation of p16(INK4a) overexpression in a large series of cervical carcinomas: concordance with SPF10-LiPA25 PCR.

The aims of this study were to assess the overexpression of p16 in formalin-fixed paraffin-embedded cervical carcinoma tissue blocks and to determine its concordance with the human papillomavirus (HPV) status using the SPF10-LiPA25 polymerase chain reaction System and its correlation with the histologic type of invasive cervical cancer (ICC) and individual HPV genotypes. A total of 205 retrospectively collected ICC cases were analyzed by p16 immunohistochemistry. HPV detection was performed by polymerase chain reaction using SPF10 broad-spectrum primers, followed by deoxyribonucleic acid enzyme immunoassay and genotyping by reverse hybridization line probe assay (LiPA25). Of 205, 188 analyzed (91.7%) ICC cases showed p16 overexpression, whereas 181 (83.3%) cases were HPV positive using HPV LiPA testing. One hundred and seventy four (84.9%) cases were both p16 and HPV LiPA positive, indicating a positive concordance of 89.9% between both techniques (κ index agreement of 0.43; P<0.001), and no statistically significant difference (McNemar test, P>0.05). Squamous cell carcinomas were strongly positive compared with the adenocarcinomas (93.6% vs. 75% of the cases, respectively). When performed on formalin-fixed paraffin-embedded cervical tissue specimens, the higher positivity rate of p16 immunohistochemistry as compared with HPV DNA testing may allow identifying HPV-related ICC cases in which HPV testing was negative.