P3.09-03 Alteration of Gut Microbiome in Lung Cancer Patients

Impact of Gut Dysbiosis on the Risk of Non-Small-Cell Lung Cancer

Background: The imbalance of gut microbiota, dysbiosis, is associated with various malignant diseases. This study aimed to identify the characteristics of gut microbiota in age-matched treatment-naïve non-small-cell lung cancer (NSCLC) patients and healthy individuals to investigate possible gut-microbe-related pathways involved in the development of NSCLC. Methods: We enrolled 34 age-matched NSCLC patients and 268 healthy individuals. Hypervariable V3−V4 amplicons of 16S rRNA in freshly collected fecal samples were sequenced. Diversity, microbial composition, functional pathways, smoking history, and gut-microbe-related comorbidities were analyzed to assess the factors associated with the risk of NSCLC. Results: Microbial alpha diversity was decreased in the patients with NSCLC, and beta diversity was significantly different between the patients and controls (p < 0.001). After adjustments for sex, smoking history, hypertension, diabetes mellitus, chronic obstructive pulmonary disease, and 11 abundant microbes with significant differences between the patients and controls, the enrichment of Anaerotruncus spp. and Bacteroides caccae was associated with an increased risk of NSCLC (p = 0.003 and 0.007, respectively). The areas under receiver operating characteristic curves were 71.4% and 66.9% for Anaerotruncus spp. and Bacteroides caccae, respectively (both p < 0.001). Furthermore, the abundance of Bacteroides caccae was positively correlated with steroid hormone biosynthesis (p < 0.001), N-glycan biosynthesis (p = 0.023), glycosaminoglycan degradation (p < 0.001), lipoic acid metabolism (p = 0.039), peroxisome (p < 0.001), and apoptosis (p < 0.001), but inversely related to glycerolipid metabolism (p < 0.001). Anaerotruncus spp. was positively associated with decreased biosynthesis of ansamycin only (p = 0.001). No overlapping signaling pathways were modulated by Bacteroides caccae or Anaerotruncus spp. Conclusions: Our results revealed that fecal Anaerotruncus spp. and Bacteroides caccae were abundant and may be associated with the risk of NSCLC regardless of sex, smoking history, and gut-microbe-related comorbidities. Further investigations on the mechanism underlying the potential association between gut dysbiosis and the development of NSCLC are warranted.

The association between acid-suppressive agent use and the risk of cancer: a systematic review and meta-analysis

BACKGROUND

Acid-suppressive agents (ASAs) may be associated with cancer; previous studies reported that the risk of cancer with acid suppressants has differed depending on the site of cancer. Here, we conducted a systematic review and meta-analysis of the association between ASA use and the type of cancer risk.

METHODS

MEDLINE, EMBASE, and Cochrane library databases were searched for publications up to the end of September 2019 for MeSH terms and text words related to cancer and ASAs. Studies on the association between ASAs and cancer risk, which included a control group and reported the relative risk of cancer, were included. The inverse-variance random effect model was used to estimate the pooled relative risk (RR) and 95% confidence interval (CI), and subgroup analysis for type of acid suppressants, drug uptake duration, and cumulative doses was performed. Heterogeneity was assessed using the I² test and Q statistic.

RESULTS

Thirty-nine cohort and case-control studies were included. ASA use was found to be significantly associated with a 46% higher risk of gastric cancer (RR, 1.46; 95% CI, 1.18-1.80) and a 53% higher risk of liver cancer (RR, 1.53; 95% CI, 1.31-1.78) compared with nonuse; however, there was no significant association for esophageal, colorectal, pancreatic, lung, breast, prostate, and kidney cancer; melanoma; and lymphoma.

CONCLUSIONS

ASAs were significantly associated with an increased risk of gastric and liver cancer; therefore, special attention of ASA use considering the potential risk of gastric and liver cancer is needed.