Application of a Saliva-Based Liquid Biopsy for the Detection of HPV in Patients With Oral Cavity Squamous Cell Carcinoma (OCSCC).

BACKGROUND

Human papilloma virus (HPV) is a DNA virus capable of infecting mucous membranes. In most cases, the infection is cleared by the immune system, but a prolonged exposure to HPV can progress to cancer. 40%-60% of head and neck squamous cell carcinomas (HNSCC) are linked to HPV, which is considered a risk factor especially among young people in industrialized countries. HNSCC are not identified early due to their slow growth and their locations not being easy to see. Despite the prognostic value of HPV, the use of HPV-DNA as a diagnostic marker is not fully developed. HPV-DNA can be detected in saliva specimens of patients with HPV-driven cancers. Considering this, we employed saliva samples to optimize a non-invasive RT-PCR assay for HPV infection and prove the hypothesis that the presence of HPV DNA represents a risk factor for Oral Cavity Squamous Cell Carcinoma (OCSCC). The potential of this work is to highlight how an HPV screening program based on salivary testing can be useful for early cancer detection and patient monitoring.

METHODS

In this retrospective study, 127 patients and 93 control samples were tested for the presence of HPV in self-collected saliva specimens. Viral DNA was extracted from saliva using an automated instrument. A multiplex RT-PCR was employed for the detection of the (28 most frequent HPV Types). Patients' demographics were collected in a clinical database. Statistics were performed by STATA16, and significance was set at p < 0.05.

RESULTS

Most patients had a diagnosis of OCSCC (49.1%), 38%-9% of which involved the tongue. 9.6% resulted positive for HPV DNA in saliva, specifically for high-risk subtypes (42.9% type 58; 28.6% types 45, 59, 39 and 9.6% type 16, 18). HPV+patients were compared to those who were found negative. HPV infection was related to the TNM stage, especially with pT2N1 (p ≤ 0.002) and with primary vs. relapsed tumors (p = 0.004). Independent of site, the assay reached a sensitivity of 91.7%, a specificity of 100%, and an agreement of 98.5%, compared to the oropharyngeal swab (Cohen's Kappa = 0.947; n = 65). Test PPV was 100% (95% CI 71.5-100), while NPV was 98.1% (95% CI 90.1-100).

CONCLUSIONS

Our findings indicate that salivary HPV testing is a non-invasive and convenient test that could become part of routine clinical management for HPV infection of the oral cavity. This test represents an ideal mode of screening of asymptomatic individuals and a long-term monitoring tool for HPV-driven cancer patients.