Detection of human papilloma virus-E6/E7 proteins of high-risk human papilloma virus in saliva and lesional tissue of oral squamous cell carcinoma patients using nested multiplex polymerase chain reaction: A comparative study

INTRODUCTION: Human papilloma virus (HPV)-associated oral squamous cell carcinoma (OSCC) shows different biological behavior as compared to tobacco-induced OSCC. Mere presence of HPV in OSCC is of no clinical significance; however, the integration of HPV-DNA through E6/E7 gene into the host genome is important as it affects the development and progression of OSCC. AIM: The aim of this study was to determine the presence of E6/E7 proteins of high-risk (HR) HPV (HPV16 and HPV18) in saliva as well as lesional tissue of OSCC patients and to determine the use of saliva as an alternative to tissue for E6 and E7 proteins in OSCC. MATERIALS AND METHODS: Histopathologically confirmed 47 cases of OSCC were taken up for the study. The tumor tissue and saliva sample of each patient were obtained to detect the presence of HPV16 and HPV18 along with E6/E7 proteins in both samples by nested multiplex polymerase chain reaction (NMPCR). The data were analyzed using Student t-test (2 tailed) and Wilcoxon signed-ranks test. RESULTS: In tumor tissue, 40.42% of cases showed HPV16 (19/47) positivity while 34.04% were HPV18 (16/47) positive; whereas, in salivary sample, 31.91% showed HPV16 (15/47) positivity while 25.53% of cases were HPV18 positive (12/47). Mean age of participants was 46.7 years, males showed no significant difference from females in the prevalence of HPV 16/18 with tongue being the most common site for the occurrence. There was no statistically significant difference for HPV16/18 presence in tissue and saliva sample of OSCC. Taking lesional tissue sample as standard, sensitivity and specificity for HPV16 and HPV18 in saliva by NMPCR was estimated at 68.42% and 92.86%, respectively. The accuracy level of NMPCR detection for HPV16 was 82.98% and HPV18 was 65.96%. CONCLUSION: The study revealed no significant difference in the prevalence of HPV (16/18) among tissue and saliva of OSCC patients in Indian population. The study also found no difference in the level of DNA content of HPV in saliva and tissue indicating that saliva can be used as an alternative predictor of HPV positivity in OSCC.