Improving Early Diagnosis Of Cervical Cancer Lesions Using p16INK4a Biomarkers On Cellblocks From Cervical Smears

Abstract

Globally, cervical cancer is the second most regular malignant growth in females after breast cancer. Timely recognition of premalignant lesions is an essential segment in the decrease of related morbidity and mortality. Though Pap -Smear test has been a helpful screening device despite hampered by high intra and interobserver changeability, false negatives at 20– 30% and false positives at 5– 70%.

Objective: The study was to determine the role of p16INK4a biomarker in the identification of low grade Squamous Intraepithelial lesions in cellblocks prepared from Pap smears and subsequently compared with previous Pap smear results with Colposcopy and Cellblock results.

Methodology:  This was a laboratory-based, prospective study with a parallel comparative arm at Kenyatta National Hospital Reproductive health clinic (66). All patients who had abnormal Pap smear reports and referred for Colposcopy, and consented for the study were enrolled. A smear
was taken just before taking a Colposcopy biopsy. The cytobrush was immediately put in Acid alcohol fixative centrifuged and deposits wrapped in a filter paper and processed histologically to form a cellblock. Colposcopy biopsies were then retrieved from KNH histology Lab and both samples subjected to Routine histological stain and eventually with biomarker p16. Total of 85 samples was collected.

Results: There was a significant level of agreement between Pap smears and cellblock findings on the routine Histological stain. Of the 58 cases analyzed Colposcopy had (39%) 27 negatives and (45%) 31 positives while cellblock had (48%) 33 negative and (36%) 25 positive for pre and malignancy with a confidence interval of 0.016 as the margin of error. Biomarker Colposcopy had (43%) 30 negativity and (41%) 28 positivity while cellblock had negativity of (46%) 32 and positivity of (38 %) 26

Conclusion: Poor inter-rater agreement resulting to mortality and morbidity associated with false positives and false negatives, cellblock prepared from residues of cytobrush stained with Haematoxyline and Eosin and biomarker is likely to circumvent all the above, together with minimizing loss to follow up as patients only visit health facility once and they acquire all the results without resampling hence drastically reducing the cost of colposcopy, which require highly specialized equipment and experienced personnel who are very few and difficult to find.