Liquid-based cytology: do ancillary techniques enhance detection of epithelial abnormalities?

PURPOSE: Cervical cancer is the fourth most common cancer in women worldwide with very high incidence in India. Liquid-based cytology (LBC) provides the use of ancillary techniques in addition to a good morphology and detection of cytologic abnormalities. The current study was designed to assess the diagnostics of P16INK4a immunoexpression, p16 promoter hypermethylation, human papilloma virus (HPV), and DNA ploidy in LBC samples with cervical precancer and cancer.

METHODS: A series of LBC samples categorised by Bethesda system including 22 atypical squamous cells of undetermined significance (ASC-US), 21 low-grade squamous intraepithelial lesion (LSIL), 41 high-grade squamous intraepithelial lesion (HSIL), 54 squamous cell carcinoma (SCC), and 26 controls with normal cytology were included. Ancillary techniques evaluated included P16INK4a immunoexpression, p16 promoter methylation DNA ploidy by flow cytometry, and HPV was detected using PGMY09/PGMY11 primers.

RESULTS: The test positivity rate of p16 expression in women with ASC-US, LSIL, HSIL, and SCC was 21.1, 39.0, 67.7, and 85.4%. For the p16 methylation the corresponding test positivity rate was 36.4, 76.2, 92.7, and 92.6%. The test positive rate of HPV in women with ASC-US, LSIL, HSIL, and SCC was 45.5, 76.2, 87.8, and 92.6%. Diploid G1 and diploid S values significantly (p < 0.05 or p < 0.01) discriminate LSIL versus HSIL and LSIL versus. SCC.

CONCLUSIONS: P16 gene promoter methylation and HPV seem more sensitive in detection of ASC-US and LSIL cytology with higher specificity. Diploid G1 and diploid S phase study provides progressive change in parameters with progression from LSIL to HSIL and SCC.