Evaluation of enzyme-linked immunosorbent assay plasma p16INK4a protein in squamous cell carcinoma in uterine cervix

Abstract

Background: Cervical cancer is one of the common cancers in females. The common method of screening is Pap test which has low sensitivity. Hence, better methods are explored with different biomarkers, of which estimation of P16 protein can be opted in early detection of cervical cancer. Materials and Methods: Seventy cases and seventy controls were considered for the study. Cases were invasive squamous cell carcinoma (SCC) of cervix confirmed by histopathology. Controls were healthy age-matched females. The blood sample of cases and controls was collected in K2 Ethylenediaminetetraacetic acid vacutainer, and the separated plasma was subjected to estimation of P16 protein by quantitative sandwich Enzyme-Linked ImmunoSorbent Assay method. The data were analyzed for the association between p16 protein in plasma in cases and controls. Results: The age among cases and controls ranged from 30 to 80 years. The P16 levels among cases ranged from 3.4 to 19.6 ng/ml with a mean of 7.24 ± 2.35 ng/ml. The plasma P16 level in controls ranged between 0.9 and 9.7 ng/ml with mean of 4.1 ± 2.22 ng/ml. At cutoff more than 4.8 ng/ml in cases, the sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were 92.86%, 72.86%, 77.4%, 91.1%, and 82.86%, respectively. The specificity increased with increase in plasma p16 levels. The P16 levels were maximum in stage IV disease. Conclusion: This was a pilot study to detect the plasma p16INK4a levels in SCC of cervix. The levels of plasma p16 protein between 3.9 and 5 ng/ml can be considered as the range for the test to be positive. In clinically suspected cases of cervical cancer, levels more than 4.8 ng/ml can be considered for the diagnosis as point of care test.