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Background: P16(INK4a) is a biomarker for transforming HPV infections that could act as an adjunct to current cytological and histological assessment of cervical smears and biopsies, allowing the identification of those women with ambiguous results that require referral to colposcopy and potentially treatment., Material and Methods: We conducted a systematic review of all studies that evaluated the use of p16(INK4a) in cytological or histological specimens from the uterine cervix. We also estimated the mean proportion of samples that were positive for p16(INK4a) in cytology and histology, stratified by the grade of the lesion., Results: Sixty-one studies were included. The proportion of cervical smears overexpressing p16(INK4a) increased with the severity of cytological abnormality. Among normal smears, only 12% (95% CI: 7-17%) were positive for the biomarker compared to 45% of ASCUS and LSIL (95% CI: 35-54% and 37-57%, respectively) and 89% of HSIL smears (95% CI: 84-95%). Similarly, in histology only 2% of normal biopsies (95% CI: 0.4-30%) and 38% of CIN1 (95% CI: 23-53%) showed diffuse staining for p16(INK4a) compared to 68% of CIN2 (95% CI: 44-92%) and 82% of CIN3 (95% CI: 72-92%)., Conclusion: Although there is good evidence that p16(INK4a) immunostaining correlates with the severity of cytological/histological abnormalities, the reproducibility is limited due to insufficiently standardized interpretation of the immunostaining. Therefore, a consensus needs to be reached regarding the evaluation of p16(INK4a) staining and the biomarker needs to be assessed in various clinical settings addressing specific clinical questions.

Objective: To study the cellularity of liquid-based preparations (LBPs) for normal, abnormal and false negative cervical cytology cases., Study Design: A series of 1,875 LBPs obtained by a split-sample protocol was examined. Slides had been examined by at least one cytotechnologist. All abnormals were reviewed by at least two cytopathologists. The cellular objects were counted using a fully automated microscope. Cellularity was evaluated for the entire population, normal (< LSIL) slides, abnormal (LSIL+) slides and "false negative" slides. False negatives were identified as those with an initial impression of < LSIL and (1) the reference pathologist's impression of the slide was LSIL+, (2) the simultaneous conventional smear was LSIL+, or (3) a cervical biopsy was LSIL+. Descriptive statistics and graphic comparisons were used., Results: There were 192 confirmed abnormal cases and 1,683 normal cases, of which 53 were false negative. The frequency distributions of cellularity for the entire population and each category were skewed-right nonnormal. Median cell counts of the entire series, normals, abnormals and false negatives were 60,510, 59,822, 70,523 and 64,036 respectively. Cell counts at 2.5 percentiles were 8,677, 7,891, 11,864 and 6,009, respectively. The population of abnormal slides tended to have higher cellularity. The population of false negative slides could not be distinguished by their cellularity., Conclusion: Cellularity does not provide assurance of adequacy. Any cellularity criterion should be based on measurement of the prevalence of abnormal cells on abnormal slides.