BackgroundThe endogenous microbiome of healthy individuals in the oral cavity is diverse, representing over 700 different bacterial species. Some of these species may become opportunistic if certain elements in the microenvironment and host-response in the oral cavity are altered. Imbalance in microbiome composition, defined by higher or lower levels of relative abundance and microbial gene expression changes, has been linked to different forms of hematological cancer.HypothesisWe hypothesize we will identify unique oral microbiome profiles in hematological cancer patients when compared to healthy controls. Additionally, we expect to determine significant differences in the oral microbiome beta-diversity of lymphoma patients when compared to acute myelogenous leukemia (AML) patients.Objective1) To identify unique oral microbiome profiles of hematological cancer patients when compared to healthy control subjects.2) To compare the oral microbiome profiles of lymphoma patients and AML patients prior to cancer treatment.MethodsSaliva samples and swabs of buccal mucosa, supragingival plaque and tongue were collected from hematological cancer patients (N=51), prior to cancer treatment, and healthy control subjects (N=38). Next generation sequencing (16S-rRNA gene V3-V4 region) was used to determine the relative abundance of bacterial taxa present at the genus and species levels. Differences in oral microbiome beta-diversity were tested using PERMANOVA by comparing hematological cancer patients vs. healthy controls patients (N=38) [Monte-Carlo corrected p values (α=0.05)]. Linear discriminant analysis (LDA) effect size (LEfSe; Log LDA threshold >0.005) analysis was performed to identify differentiating bacterial genus and species probes for the above mentioned pairwise comparisons.ResultsThere were significant differences in the oral microbiome beta-diversity of hematological cancer patients compared to healthy controls (p=0.0001). LEfSe analysis showed significant LDA scores for 51 probes differentiating hematological cancer patients from healthy controls. Furthermore, there was a significant difference in the beta diversity of the oral microbiome of both lymphoma and AML patients when compared to each other as well as to healthy control subjects.ConclusionHematological cancer patients had distinct oral microbial profiles compared to healthy controls. Additionally, oral microbiome profiles of lymphoma and AML patients were significantly different. Further investigation into the mechanistic interaction of the oral microbiome with the microenvironment in oral cavity and the host immune system is warranted.