Epstein-Barr virus prevalence is associated with OSCC and seems to be enhanced by betel quid chewing, suggesting that EBV may, together with betel quid chewing, act as an important etiological risk factor of OSCC.

Oral cancer is a common site of head and neck cancer, and is relatively frequent in Northeast Thailand. The objective of this hospital-based, case-control study was to determine associations with risk factors. A total of 104 oral cancer cases diagnosed between July 2010 and April 2011 in 3 hospitals were matched with control subjects by age, sex and hospital. Data were collected by personal interview. There were significant associations between oral cancer and tobacco smoking (OR=4.47; 95%CI=2.00 to 9.99), alcohol use among women (OR=4.16; 95%CI=1.70 to 10.69), and betel chewing (OR=9.01; 95%CI=3.83 to 21.22), and all three showed dose-response effects. Smoking is rare among Thai women (none of the control women were smokers), but betel chewing, especially among older women, is relatively common. We did not find any association between practicing oral sex and oral cancer.

Human papillomavirus (HPV) is an independent risk factor for development of oral squamous cell carcinoma (OSCC). This study aimed to investigate the role of HPV infection and the trend in percentage of HPV-associated OSCC over a 5-year period in northeastern Thailand. In this case-control study, 91 exfoliated oral cell samples and 80 lesion cell samples from OSCC cases and exfoliated oral cells from 100 age/gender-matched controls were collected. HPV infection was investigated by PCR using GP5+/GP6+ primers followed by HPV genotyping using reverse line blot hybridization. Quantitative RT-PCR was used to evaluate HPV oncogene transcription. Temporal trends of HPV infection were evaluated in archived formalin-fixed paraffin-embedded (FFPE) OSCC tissues using in situ hybridization. HPV DNA was found in 17.5% (14/80) of lesion samples from OSCC cases and 29.7% (27/91) of exfoliated oral cell samples from the same cases. These values were significantly higher than in exfoliated oral cell samples from controls (13%, 13/100). HPV-16 was the genotype most frequently found in OSCC cases (92.8%, 13/14 infected cases). Interestingly, HPV oncogene mRNA expression was detected and correlated with OSCC cases (P < 0.005). Of 146 archived FFPE OSCC samples, 82 (56.2%) were positive for high-risk HPV DNA and 64 (43.8%) cases were positive for HPV E6/E7 mRNA expression. There was a trend of increasing percentage of HPV-associated OSCC from 2005 to 2010. This was especially so for females with well-differentiated tumors in specific tongue sub-sites. We suggest that HPV infection plays an important role in oral carcinogenesis in northeastern Thailand.

Conclusion:We confirm that NoV infection is endemic in Ho Chi Minh City and report the novel emergence of NoV GII.4-2010 (New Orleans) variant.