title: Immunocytochemical expression of p16INK4A and Ki-67 in cytologically negative and equivocal pap smears positive for oncogenic human papillomavirus.
abstract: This study was designed to analyze the cross-sectional comparison of the p16 and Ki-67 immunocytochemical expression in negative and equivocal (atypical squamous cells of undetermined significance (ASC-US)) liquid-based cytology (LBC) samples testing positive for high-risk human papillomavirus (HPV) types with HC2 assay or polymerase-chain reaction (PCR). A series of 199 consecutive LBC specimens derived from the same number of women participating in the ongoing Latin American Screening Study at Leonor Mendes de Barros Hospital, Sao Paulo, were analyzed using immunocytochemistry for expression of p16 and Ki-67 in negative and equivocal LBC samples testing positive for high-risk HPV types with hybrid capture II test (HC2) or PCR. All patients with at least one test positive (cytology, PCR, and/or HC2) were followed each 6 months for 3 years. The follow-up procedure consisted of visual examination, colposcopic inspection, cytology, and HC2 assay. Among the negative cytologic samples, 101 were HPV-positive and 55 HPV-negative. Of the HPV-positive group, 59 of 101 cases (58.4%) were positive for both p16 and Ki67 immunostaining, and 17 of 101 (16.8%) were negative for both. The proportion of Ki-67-positivity increased almost in parallel with the increasing grade of p16-positivity (p = 0.0001 for linear trend). In the HPV-negative group, both markers were negative in 41 of 55 cases (74.5%), and no statistical relationship was observed between the two markers (Pearson, p = 0.595). HPV-positive ASC-US samples demonstrated a simultaneous positive immunoreaction for p16 and Ki67 in 11 of 16 cases (68.7%), whereas 3 (18.7%) were concurrently negative. The relationship between the two markers was of borderline significance (Pearson, p = 0.053), but no linear relationship was found between the graded p16 and Ki-67 expression (p = 0.065 for linear trend). In the HPV-negative ASC-US group, there was no statistical association between the graded p16 and Ki-67 positivity (Pearson, p = 0.281). After 36 months of follow-up of the ASC-US patients, 6 women still displayed ASC-US smear, of which 4 of 6 were HPV-positive and expressed both p16 and Ki-67 markers. Two of 43 ASC-US smears had high-grade squamous intraepithelial lesions diagnosed (4.6%), and 1 had low-grade squamous intraepithelial lesion (2.3%). All of those were positive for HPV, p16 and Ki-67. Patients with ASC-US diagnosis and positive high-risk HPV status and positive for p16 Ki67 should be carefully observed to exclude occurrence of a squamous intraepithelial lesion. The combination of these two markers can be a useful implement for management of women with equivocal cytology.
authors.affiliation: Pathology Division, Adolfo Lutz Institute, São Paulo, Brazil.
authors.forename: Adhemar
authors.initials: A
authors.lastname: Longatto Filho
authors.forename: Maria Lúcia
authors.initials: ML
authors.lastname: Utagawa
authors.forename: Neuza Kasumi
authors.initials: NK
authors.lastname: Shirata
authors.forename: Sônia Maria Miranda
authors.initials: SM
authors.lastname: Pereira
authors.forename: Gislene M
authors.initials: GM
authors.lastname: Namiyama
authors.forename: Cristina Takami
authors.initials: CT
authors.lastname: Kanamura
authors.forename: Gilda da Cunha
authors.initials: Gda C
authors.lastname: Santos
authors.forename: Marilene Almeida
authors.initials: MA
authors.lastname: de Oliveira
authors.forename: Alda
authors.initials: A
authors.lastname: Wakamatsu
authors.forename: Suely
authors.initials: S
authors.lastname: Nonogaki
authors.forename: Cecília
authors.initials: C
authors.lastname: Roteli-Martins
authors.forename: Celso
authors.initials: C
authors.lastname: di Loreto
authors.forename: Maria da Gloria
authors.initials: Mda G
authors.lastname: Mattosinho de Castro Ferraz
authors.forename: Marina Yoshiê Sakamoto
authors.initials: MY
authors.lastname: Maeda
authors.forename: Venâncio A F
authors.initials: VA
authors.lastname: Alves
authors.forename: Kari
authors.initials: K
authors.lastname: Syrjänen
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis*; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000096:biosynthesis*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000096:biosynthesis*; D065006:Papanicolaou Test; D027383:Papillomaviridae; D030361:Papillomavirus Infections / Q000150:complications*; D016133:Polymerase Chain Reaction; D011230:Precancerous Conditions / Q000175:diagnosis* / Q000378:metabolism / Q000821:virology; D014412:Tumor Virus Infections / Q000150:complications; D002583:Uterine Cervical Neoplasms / Q000175:diagnosis* / Q000378:metabolism / Q000821:virology; D014626:Vaginal Smears; D002578:Uterine Cervical Dysplasia / Q000175:diagnosis / Q000378:metabolism / Q000821:virology
chemical_list: D014408:Biomarkers, Tumor; D019941:Cyclin-Dependent Kinase Inhibitor p16; D019394:Ki-67 Antigen