Background: Cigarette smoking and opium use are associated with periodontal disease, which is linked to the changes in oral microbiome. We aimed to study the association between cigarette and/or opium use with the oral microbiome.

Methods: A total of 558 subjects included in the present analysis were from a case-control study of pancreatic cancer in Tehran, Iran conducted from 2011 to 2015. A questionnaire ascertained demographic, cigarette and opium use history, and lifestyle characteristics, and participants provided saliva samples. DNA was extracted using the DSP DNA Virus Pathogen kit and 16S rRNA gene sequencing was performed on the MiSeq. Sequences were clustered into amplicon sequence variants (ASVs) using QIIME2 and taxonomy was assigned against the Human Oral Microbiome Database. Logistic regression, MiRKAT and zero-inflated β regression models were calculated with adjustment for age, sex, body mass index, and case status.

Results: The average number of observed ASVs for users of cigarette only (82.13 ± 38.55), opium only (76.19 ± 40.71), or both cigarette and opium users (77.80 ± 42.83) were significantly lower than never cigarette/opium users (95.10 ± 44.03). Similar trends were observed for the Shannon index. The microbial communities appeared to differ by cigarette and opium use as indicated by the MiRKAT models from the three beta diversity matrices. Four phylum level relative abundances were associated with cigarette and opium use, while the presence/absence of nine genera was associated with users of both cigarette and opium in the zero-inflated β regression models. The phylum Firmicutes and class Bacilla (Firmicutes) were significantly associated with opium only use, which showed marginally significant adjusted P values in users of both cigarettes and opium. No taxa were specifically associated with cigarette use only.

Conclusion: Cigarette and/or opium use were related to overall oral microbiome community composition and the presence/absence as well as relative abundance of multiple taxa. Further studies are needed to investigate the impact of the changes to the oral microbiome through cigarette and/or opium use on human health and disease status.

Citation Format: Zeni Wu. Cigarette smoking and opium use in relation to the oral microbiome in Iran [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4666.