Baseline oral microbiome and all-cancer incidence in a cohort of non-smoking Mexican American women.

Zhang, Xiaotao; Hoffman, Kristi L; Wei, Peng; Elhor Gbito, Kplola Y; Joseph, Reji; Li, Fangyu; Scheet, Paul; Chang, Shine; Petrosino, Joseph F; Daniel, Carrie R

Given the increasing evidence that the oral microbiome is involved in obesity, diabetes and cancer risk, we investigated baseline oral microbiota profiles in relation to all-cancer incidence among non-smoking women enrolled in a Texas cohort of first- and second-generation immigrants of Mexican origin. We characterized the 16Sv4 rDNA microbiome in oral mouthwash samples collected at baseline from a representative subset of 305 non-smoking women, aged 20-75 years. We evaluated within (alpha) and between sample (beta) diversity by incident cancer status and applied Linear Discriminant Analysis (LDA) Effect Size analysis to assess differentially abundant taxa. Diversity and candidate taxa in relation to all-cancer incidence was evaluated in multivariable (MV)-adjusted Cox regression models. Over 8.8 median years of follow-up, 31 incident cancer cases were identified and verified. Advanced age, greater acculturation and cardiometabolic risk factors were associated with all-cancer incidence. Higher alpha diversity (age-adjusted Pdiff<0.01) and distinct biological communities (Pdiff=0.002) were observed by incident cancer status. Each unit increase in the Shannon diversity index yielded >8-fold increase in all-cancer and obesity-related cancer risk [MV-adjusted HR (95% CI): 8.11 (3.14, 20.94) and 10.72 (3.30, 34.84), respectively] with similar findings for the inverse Simpson index. Streptococcus was enriched among women who did not develop cancer, while Fusobacterium, Prevotella, Mogibacterium, Campylobacter, Lachnoanaerobaculum, Dialister and Atopobium were higher among women who developed cancer (LDA score≥3, q-value<0.01). This initial study of oral microbiota and overall cancer risk in non-smoking Mexican American women suggests the readily accessible oral microbiota as a promising biomarker.