Fig. 3: The carcinogenesis process is triggered by HPV integration into the host cell genome.

Following an infection with HPV, the integration process could take place in infected cells that evade the immune system and are not cleared by apoptosis. During chronic infection, infected cells can become immortalised (transformed) and by accumulating various alterations in tumour suppressors and oncogenes eventually progress to cancer. The HPV-positive pre-cancer and cancer cells harbour integrated and non-integrated HPV. The HPV-positive cells with a higher rate of viral integration are enriched at the final stages of HNSCC and correlate with a poor patient prognosis. HPV human papillomavirus, HNSCC head and neck cancer squamous cell carcinoma.