No role for human papillomavirus infection in oral cancers in a region in southern India

Abstract

Oral cancer is a major public health issue in India with~77,000 new cases and 52,000 deaths yearly. Paan chewing, tobacco and alcohol use are strong risk factors for this cancer in India. Human papillomaviruses (HPVs) are also related to a subset of head and neck cancers (HNCs). We examined the association between oral HPV and oral cancer in a sample of Indian subjects participating in a hospital-based case-control study. We recruited incident oral cancer cases (N 5 350) and controls frequencymatched by age and sex (N 5 371) from two main referral hospitals in Kerala, South India. Sociodemographic and behavioral data were collected by interviews. Epithelial cells were sampled using Oral CDx V R brushes from the oral cancer site and the normal mucosa. Detection and genotyping of 36 HPV genotypes were done using a polymerase chain reaction protocol. Data collection procedures were performed by qualified dentists via a detailed protocol with strict quality control, including independent HPV testing in India and Canada. HPV DNA was detected in none of the cases or controls. Associations between oral cancer and risk factors usually associated with HPV infection, such as oral sex and number of lifetime sexual partners, were examined by logistic regression and were not associated with oral cancer. Lack of a role for HPV infection in this study may reflect cultural or religious characteristics specific to this region in India that are not conducive to oral HPV transmission. A nationwide representative prevalence study is needed to investigate HPV prevalence variability among Indian regions.Worldwide, nearly 300,000 new cases of oral cancers are diagnosed each year, accounting for 145,000 deaths. Approximately 77,000 new cases and 52,000 oral cancer-related deaths occur yearly in India, representing a quarter of all incident cases in the world. 1 Known risk factors include tobacco smoking and chewing, high alcohol consumption and, in a country such as India, paan chewing. 2 Oral human papillomavirus (HPV) infection has recently been recognized as another important risk factor for head and neck cancer (HNC), mainly for the oropharyngeal cancer subsite. In fact,

Notch pathway activation is essential for maintenance of stem-like cells in early tongue cancer

“…Where exome sequence was available, the absence of HPV was re-confirmed using HPVDetector, as previously described [16]. TSCC samples of Indian origin to be HPV negative is consistent with other studies [17-19]. …”

Prevalence of human papillomavirus in oral rinse samples from healthy individuals in northern Thailand

“…However, some studies showed that HPV DNA was not detected in the oral cancers or controls. This may reflect specific cultural or religious characteristics …”

“…In northeastern Thailand, HPV DNA was detected in about 13% of exfoliated buccal cell samples from the normal population . By contrast, in South India, HPV DNA was not found in normal oral mucosal samples, nor in epithelium cells from the sites of oral cancers …”

“…The association between HPV infection, especially high‐risk HPV (HR‐HPV), and OPSCC has been reported in many countries. HPV DNA was detected 0%‐36% of OPSCC cases, with HPV16 being the most common genotype, followed by HPV18, HPV31, HPV33, HPV51, HPV52, and HPV62 . An association between HPV16 and OPSCC has been identified in older age groups [odds ratio 16.0 (95% CI: 1.7‐153.6)] .…”

“…An association between HPV16 and OPSCC has been identified in older age groups [odds ratio 16.0 (95% CI: 1.7‐153.6)] . In oral rinse samples (mouth rinse or mouthwash) from healthy individuals, HPV infection was found in 0‐26% of cases . In northeastern Thailand, HPV DNA was detected in about 13% of exfoliated buccal cell samples from the normal population .…”