Background: Pancreatic cancer is a lethal tumor with a poor prognosis. The connection between pancreatic cancer and gut microbiota is less reported. Objectives: This study analyzed microbial characteristics in patients with pancreatic cancer from the tropical area of China and explored the potential impact of the characteristic microflora on pancreatic cancer. Methods: Stool samples and blood test indices of participants were collected in Hainan, China. Metagenomic sequencing was used to analyze the gut microbiota characteristics. The R corrplot package was used to analyze the correlation between gut microbiota and blood test indices. Results: The microbial community in pancreatic cancer were clustered together and significantly separated from controls. The Simpson index was increased significantly in pancreatic cancer compared to controls. The abundances of butyrate-producing bacteria (Anaerostipes hadrus, Lachnoclostridium phocaeense, and Romboutsia ilealis), Bifidobacteria, and [Eubacterium] eligens were significantly decreased, while Fusobacterium, Enterobacter, and Enterococcus were significantly increased in pancreatic cancer. Prevotella copri may have a vital role in the bacterial interaction network. Pathways connected to metabolism, environment (bacterial secretion system), genetic information (protein export and ribosome), and human diseases (infectious diseases and drug resistance) were increased in the pancreatic cancer group. Butyrate-producing bacteria (butyrate-producing bacterium SS3/4, A. hadrus, R. intestinalis, and Faecalibacterium prausnitzii) and Bifidobacteria were significantly negatively correlated with the neutrophil-to-lymphocyte ratio. Conclusions: The gut microbiome was distinct in patients with pancreatic cancer from the tropical area of China. Changes in intestinal flora abundance and metabolic pathways may play an essential role in the occurrence and development of pancreatic cancer.

Objective To systematically review the antitumor activity of fucoidan based on the results of animal experimental studies. Methods The databases of the Cochrane Library, PubMed, Ovid MEDLINE, Web of Science, Embase, China National Knowledge Infrastructure (CNKI), Sino Med, Wanfang, and Chinese Science and Technology Periodicals (CQVIP) were searched for randomized and controlled animal experiments on the antitumor activity of fucoidan. The search included studies published up to 31 December 2020, and there was no limit to the start date. Endnote X9 software was employed to manage and screen the literature, Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) was used for assessment of risk of bias, and RevMan 5.3 software was used for meta-analysis. Results A total of 23 articles were included in the study. The results showed that compared with the control group, the fucoidan intervention group had significantly inhibited tumor weight, volume, and number. The combined effect values were mean difference (MD) =−0.94, 95% confidence interval (CI): −1.10 to −0.79; MD =−0.78, 95% CI: −1.06 to −0.50; and standardized mean difference (SMD) =−3.27, 95% CI: −4.30 to −2.23, respectively. The results of subgroup analysis showed that low-dose and intragastric administration of fucoidan had the best effect on breast cancer in controlling tumor weight, low-dose and intraperitoneal injection had the best effect on multiple myeloma in controlling tumor volume, and high-dose and intraperitoneal injection of fucoidan had the best effect on melanoma in controlling the number of tumors. Conclusions The existing evidence shows that fucoidan inhibits the growth and spontaneous metastasis of tumors in numerous animal models. The tumor type, dosage, and administration method have been shown to influence the effect of fucoidan, and thus its mechanism warrants further research. As the design quality of the included studies was not high, heterogeneity and bias may have affected the accuracy of the results.

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