p16/Ki-67 dual staining in cervico-vaginal cytology: Correlation with histology, Human Papillomavirus detection and genotyping in women undergoing colposcopy

ObjectivesTo evaluate the CINtec® PLUS assay (mtm laboratories), a new immunocytochemical method for the simultaneous detection of p16INK4a and Ki-67, in liquid-based cervico-vaginal cytology, investigating the association of the dual staining with HPV infection and genotyping as well as cytological and histological abnormalities.Methods140 women with a cervico-vaginal sample obtained immediately before the colposcopy were enrolled. This cytological sample was used for HPV testing with the Linear Array HPV Genotyping Test, the dual staining with the CINtec® PLUS kit and the morphology assessment.ResultsCytology results were 38 NILM, 16 ASC-US, 32L-SIL, 54H-SIL or worse. 113 patients also had a colposcopy-guided biopsy, classified as 14 negative, 35 CIN1, 24 CIN2, 37 CIN3, 3 invasive SCC. A strong association between p16/Ki-67 and HR-HPV infection was found (COR = 6.86, 95% CI: 1.84–31.14). Importantly, the association between p16/Ki-67 positivity and HPV16 and/or 18 infection was 2-fold stronger compared to that with the infection by other HR-HPV types (COR = 9.92, 95% CI: 2.39–47.77 vs COR = 4.20, 95% CI: 0.99–20.87). In addition, p16/Ki-67 positivity rate significantly increased with the severity of the cytological and histological abnormalities (p < 0.05 in both cases). p16/Ki-67 positivity resulted strongly associated with a CIN2 + diagnosis (COR = 10.86 95% CI: 4.16–29.12).ConclusionsThis preliminary study evidenced that p16/Ki-67 immunostaining might have a relevant clinical role, since the dual staining was significantly associated with HR-HPV infection, particularly with HPV 16 and 18, and the increasing grade of the cervical lesions, the positivity for this biomarker being strongly related to the presence of a CIN2 + lesion.

► An assay for p16/Ki-67 dual staining of cervico-vaginal samples was evaluated.
► A strong association between p16/Ki-67 positivity and HR-HPV infection was found.
► p16/Ki-67 positivity rate increased with severity of cytological and histological diagnosis.
► p16/Ki-67 positivity was strongly associated with a CIN2 + diagnosis.