Abstract 643: Poor oral hygiene is associated with HPV-negative and not HPV-positive oral cancer
Authors: Shewale Jitesh B. , Pickard Robert , Gillison Maura L. 
Published: August 2019

Background Oral health and hygiene have been implicated as risk factors for oral squamous cell carcinoma (i.e. oral cavity and oropharyngeal cancers, OSCC), and we recently reported that these risk factors also dramatically alter the oral microbiome. Here we performed a more detailed analysis of associations between oral health behaviors and OSCC in a matched case-control study. We stratified our analysis to compare and contrast associations with Human Papillomavirus (HPV)-positive versus HPV-negative OSCC.

Methods Cases were patients with newly diagnosed OSCC at The Ohio State University Comprehensive Cancer Center between 2011 and 2014. Controls were patients without cancer from the same outpatient clinic who were matched (2:1) to each case on age, sex, and race. Cases were stratified by tumor high-risk HPV status (HPV-positive, n=117; HPV-negative, n=114) based on E6 or E7 mRNA expression. Data on demographics; tobacco, alcohol, and sexual history; and oral health behaviors were collected using an audio computer-assisted self-interview. Conditional logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CI), and oral health behaviors significant in univariable analysis were evaluated in separate multivariable models.

Results In univariable analysis, oral health behaviors such as low frequency of dental clinic visit, tooth brushing, and dental flossing; gum bleeding; tooth loss; and denture use significantly increased risk of HPV-negative OSCC, whereas none of these behaviors increased risk of HPV-positive OSCC. In univariable analysis, covariates associated with increased risk of HPV-negative OSCC were low education and income level, high lifetime tobacco pack-years (0, &gt;0-&lt;20, ≥20-&lt;40, &gt;40) and high lifetime heavy (≥14 drinks/week) drinking years (0, &gt;0-&lt;10, ≥10-&lt;20, ≥20). In contrast, covariates associated with increased risk of HPV-positive OSCC were low education level, high lifetime marijuana use years (0, &gt;0-&lt;10, ≥10-&lt;20, ≥20) and high no. of oral sex partners (0-2, 3-6, ≥7). After adjusting for covariates in multivariable analysis, a frequency of less than once per year dental clinic visits significantly increased risk of HPV-negative OSCC (OR = 2.28 [95% CI = 1.14-4.57]). Dental flossing less than once per day also increased risk of HPV-negative OSCC, overall (OR = 3.56 [95% CI = 1.04-12.14]) and in those without denture (OR = 4.34 [95% CI = 1.07-17.63]). In multivariable analysis, frequency of tooth brushing and gum bleeding, denture use, and tooth loss were not associated with HPV-negative OSCC.

Conclusion Poor oral health behaviors such as infrequent dental visits and dental flossing were independently associated with HPV-negative OSCC, but not with HPV-positive OSCC. These findings are consistent with a hypothesis that poor oral health behaviors alter oral microbial composition to promote chronic inflammation and the development of HPV-negative OSCC.

Citation Format: Jitesh B. Shewale, Robert Pickard, Maura L. Gillison. Poor oral hygiene is associated with HPV-negative and not HPV-positive oral cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 643.