We propose an innovative study to examine whether oral microbiome profiles are associated with risk of upper aerodigestive squamous cell cancers (UADSCC: oral, pharyngeal, laryngeal and esophageal squamous cell cancers). We have developed a unique capability to conduct microbiome research (NIH grant: 1UH2CA140233, 5R01AI063477), including the development of a novel, cost-effective 16S rRNA gene sequencing approach (Nossa, in press) and have recently reported the relationship of foregut microbiome profiles with esophageal premalignant conditions (Yang 2009). Our preliminary case-control data identify oral microbiome profiles associated with oral cancer, but an evaluation of UADSCC risk is needed where samples are collected prior to disease diagnosis, because UADSCC disease status could have influenced the observed microbial profiles in our pilot case-control study. The main goal of our study is to relate the oral microbiome in healthy subjects to risk of UADSCC. We hypothesize that microorganisms in the oral cavity potentiate UADSC carcinogenesis, potentially related to alcohol and tobacco use, the major known risk factors. Acetaldehyde, the primary metabolite of ethanol, is carcinogenic in experimental systems, while ethanol is not and genetic epidemiologic studies support a role for acetaldehyde in UADSC carcinogenesis. It is established that the oral microflora metabolize ethanol to acetaldehyde, but oral microbe-related risks for UADSCC have not been adequately evaluated. Tobacco smoke contains numerous carcinogens and we have preliminary evidence that tobacco carcinogens are also metabolized by the oral microflora. Furthermore, microbial metabolism of alcohol to acetaldehyde is potentiated in smokers. We will conduct a nested case control study (140 UADSCC cases and 420 controls) within the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial and the American Cancer Society Cancer Prevention Study II (ACS CPS II). We will characterize common oral microbial species (including non-culturables) by sequencing the 16S rRNA microbial genes in prospectively collected pre-diagnostic oral wash samples and relate the derived microbial profiles to subsequent risk of UADSCC. We propose the following specific aims: Aim 1. Classify the oral microbiome by a 16S rRNA gene sequence-based approach and by a taxonomybased approach, in 560 non-diseased subjects, of which 140 subsequently developed UADSCC and 420 did not. Aim 2. Relate alcohol and tobacco use to the oral microbiome in 420 cohort-nested healthy controls. Aim 3. Determine if the oral microbiome differs between healthy individuals who will go on to develop UADSCC (140 cases), compared to healthy individuals who do not go on to develop UADSCC (420 cohortnested controls). Secondary Aim 4. Determine whether the relationship between alcohol/tobacco use and UADSCC risk is modified by oral microbiome profiles. Impact: UADSCC is a significant disease, with more than 500,000 cases and 300,000 deaths occurring worldwide each year. Our study will identifying oral bacterial profiles related to UADSCC risk, providing direct leads to implement microbial prophylactic interventions, as a critical adjunct to alcohol and tobacco control programs in UADSCC prevention. This first prospective study with samples collected prior to diagnosis is unique and will help determine whether altered oral microbiome profiles are causally associated prospectively with the development of UADSCC. This project is timely and highly relevant to the goals of the NIH Roadmap and the NIH Human Microbiome Project (HMP).

Mark Purdue (NCI, DCEG)
Jiyoung Ahn (NYU Medical Center)
Richard Hayes (NYU Medical Center)
Susan Gapstur (American Cancer Society)
Alexander Alekseyenko (Medical University South Carolina)
George Miller (NYU Medical Center)
Deepak Saxena (NYU School of Dentistry)