Role of infectious agents in the carcinogenesis of brain and head and neck cancers

Abstract

This review concentrates on tumours that are anatomically localised in head and neck regions. Brain cancers and head and neck cancers together account for more than 873,000 cases annually worldwide, with an increasing incidence each year. With poor survival rates at late stages, brain and head and neck cancers represent serious conditions. Carcinogenesis is a multi-step process and the role of infectious agents in this progression has not been fully identified. A major problem with such research is that the role of many infectious agents may be underestimated due to the lack of or inconsistency in experimental data obtained globally. In the case of brain cancer, no infection has been accepted as directly oncogenic, although a number of viruses and parasites are associated with the malignancy. Our analysis of the literature showed the presence of human cytomegalovirus (HCMV) in distinct types of brain tumour, namely glioblastoma multiforme (GBM) and medulloblastoma. In particular, there are reports of viral protein in up to 100% of GBM specimens. Several epidemiological studies reported associations of brain cancer and toxoplasmosis seropositivity. In head and neck cancers, there is a distinct correlation between Epstein-Barr virus (EBV) and nasopharyngeal carcinoma (NPC). Considering that almost every undifferentiated NPC is EBV-positive, virus titer levels can be measured to screen high-risk populations. In addition there is an apparent association between human papilloma virus (HPV) and head and neck squamous cell carcinoma (HNSCC); specifically, 26% of HNSCCs are positive for HPV. HPV type 16 was the most common type detected in HNSCCs (90%) and its dominance is even greater than that reported in cervical carcinoma. Although there are many studies showing an association of infectious agents with cancer, with various levels of involvement and either a direct or indirect causative effect, there is a scarcity of articles covering the role of infection in carcinogenesis of brain and head and neck cancers. We review recent studies on the infectious origin of these cancers and present our current understanding of carcinogenic mechanisms, thereby providing possible novel approaches to cancer treatment.

Prevalence of Polyoma BK Virus (BKPyV) , Epstein-Barr Virus (EBV) and Human Papilloma Virus (HPV) in Oropharyngeal Cancer

“…The etiology of OSCC is considered to be multifactorial. Oncogenic viruses have also been involved in OSCC development (Hillbertz et al, 2012;Scully, 2011;Alibek et al, 2013). The cancerogenicity of HPV in humans was conducted by the International Agency for Research on Cancer (IARC) in 2007 and 2012.…”

Epstein-Barr Virus – pathogenesis, latency and cancers

“…About 90% of cases of head and neck cancer are squamous carcinoma. Squamous cell carcinoma of the head and neck (HNSCC) originates from the mucosal lining, causing tumour development in the nasal cavity and mouth, nasopharynx, larynx, esophagus, erosion and paranasal sinuses [30]. Although many potential risk factors of head and neck cancers have been identified, including smoking and chewing tobacco, alcohol consumption, poor diet combined with a hypodynamic lifestyle, acid reflux disease, haematopoetic stem cell transplantation, ionizing radiation, electromagnetic fields, and exposure to carcinogenic chemicals, various pathogenic infections also constitute an underestimated but significant risk.…”

“…Although many potential risk factors of head and neck cancers have been identified, including smoking and chewing tobacco, alcohol consumption, poor diet combined with a hypodynamic lifestyle, acid reflux disease, haematopoetic stem cell transplantation, ionizing radiation, electromagnetic fields, and exposure to carcinogenic chemicals, various pathogenic infections also constitute an underestimated but significant risk. The International Agency for Research on Cancer (IARC) estimates that in 2008, 16% of total new cases of cancer and 20% of deaths caused by cancer worldwide were due to infections [30].…”

“…According to a metaanalysis by Chen et al [30], at the PubMed database at the end of September 2014, there were more than 600 publications on the association of EBV infection with the development of gastric cancer. Meta-regression analysis is discussed in a further 39 articles published after 2014 [44].…”

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“…90% of all head and neck cancer are squamous cell carcinoma. [1,2] Estimates of prevalence of oral potentially malignant disorder are 1-5%, although higher prevalence was reported from South East Asia, usually with male preponderance. Head and Neck squamous cell carcinoma is the most common type of cancer type in India, accounting for 40% of all malignancies.…”