p16: A Molecular Marker of Cervical Cancer
Kenneth R. Shroyer (UCD)

Digital light microscopy/immunocytochemistry
Human papillomavirus (HPV) infection is the cause of almost all cases of cervical cancer but HPV testing has only a limited role in cervical cancer screening in women under age 30. Molecular studies have shown that p16 protein is expressed at high levels in cervical cancer but is generally not expressed in normal cervical mucosa. Ongoing studies are focused on the detection of p16 as a potential marker for cervical cancer screening by the Pap test. This slide demonstrates cervical squamous cells that have been processed by an indirect immunocytochemical method with monoclonal antibodies to p16. Note brown cytoplasmic staining in cells with morphologic evidence of HPV infection (koilocytosis) in a patient that was subsequently determined to have underlying high grade dysplasia. This pattern of staining supports the hypothesis that p16 could be a marker of increased risk for underlying cervical cancer.