Saliva testing may allow early detection of HPV-driven cancers

Cancer-causing high-risk human papillomaviruses (HR-HPV) are responsible for the rising incidence of head and neck cancers (HNC), particularly oropharyngeal (throat) cancers (OPC). Investigators have now found that HR-HPV DNA can be detected in saliva in most patients with HPV-driven OPC at the time of diagnosis — and developed a potentially life-saving screening program for early cancer detection and patient monitoring.

In some countries, including the United States, HNC and particularly OPC have surpassed cervical cancers as the most common HPV-driven cancer. In the early stages, these cancers are difficult to locate with imaging studies or physical examination; the oropharynx is difficult to access, and detection is further complicated if these smaller lesions are hidden in the crevices of the tonsils.

“Despite the upsurge in HPV-driven HNC, there are no early detection methods or screening strategies for this cancer type — unlike cervical cancer, which is caused by the same virus,” said Dr Chamindie Punyadeera, from the Queensland University of Technology (QUT) and Brisbane’s Translational Research Institute. “Biomarkers enabling early detection, monitoring and disease prognostication are warranted to combat the rising incidence of HPV-driven OPC.”

Dr Punyadeera and her colleagues investigated the efficacy of salivary HPV detection as a biomarker of HPV-HNC and survival patterns in patients with OPC to evaluate the utility of salivary HR-HPV as a prognostic biomarker for OPC. Their findings appear in The Journal of Molecular Diagnostics.

Saliva testing was performed on 491 patients at the time of first diagnosis of HNC and 10 patients with recurring HNC. 43% were positive for salivary HR-HPV DNA. HPV16, a high-risk strain of the virus, was detected in 92% of the HPV-positive saliva samples. The vast majority of HPV-HNC had arisen from the oropharynx, especially from the palatine tonsils and the base of the tongue, confirming that the oropharynx is the hotspot for these cancers. 72% of OPC patients were positive for HR-HPV DNA in their saliva, and tumour p16 overexpression was observed in 89.3%.

The researchers followed 215 patients with OPC for up to five years. Salivary HR-HPV-positive patients had a clear survival advantage; the median event-free survivals were 205 months for HR-HPV-positive patients, compared to 82 months for HR-HPV-negative patients. Although the number of patients with recurrent cancer in the study was small, findings indicate that salivary HR-HPV tends to be positive in the majority of patients at the locoregional point of occurrence.

“When the non-invasive nature and convenience of the collection are considered, salivary HR-HPV testing is an ideal mode of screening asymptomatic individuals and the long-term monitoring of HPV-driven HNC patients,” Dr Punyadeera said. “Our findings indicate that in the near future, salivary HR-HPV testing will become part of routine clinical management for HPV-driven OPC patients.”

“Liquid biopsy in HNC has the potential to be truly transformative,” added co-investigator Dr Sarju Vasani, from Royal Brisbane and Women’s Hospital and The University of Queensland. “It has the potential to personalise treatment selection and aid in assessing disease prognosis. It can help us select patients for adjuvant treatment and will alert us to recurrence before imaging or clinical examination has detected any specific abnormality. It is only a matter of time before these biomarkers translate from research settings to clinical practice.”

Image caption: Lead investigator Dr Chamindie Punyadeera performs saliva testing. Image credit: Chamindie Punyadeera.

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