Correlation Between Intestinal Flora Evolution And Chemotherapy Side Effects Before And After Chemotherapy For Lung Cancer

Background: Despite some advances in medicine over the past few decades,the 5-year overall survival(OS)of lung cancer still does not exceed 20%.The latest data show that lung cancer is the highest cancer incidence(11.6%)and mortality(18.4%)in the world.Because its early symptoms are not specific,so most lung cancer patients have been in the advanced stage at the time of diagnosis.Therefore,the treatment of lung cancer is a combination of surgical resection,radiotherapy,chemotherapy,targeted therapy,immunotherapy and palliative treatment.Among them,chemotherapy is a classic and important treatment for anti-cancer therapy,which can prolong the survival of patients.However,the side effects such as hematological toxicity,impaired immune function,and gastrointestinal toxicity after chemotherapy have limited the use of chemotherapy drugs.The human gut is home to more than 1,000 species of microbes that encode some five million genes and have a total of 1,014 cells,10 times the number of human cells combined.These microbes can include bacteria,viruses and fungi,the most widely studied of which are bacteria.The majority of bacteria are anaerobic bacteria,among which Bifidobacterium and Lactobacillus are recognized as the typical beneficial bacteria.Some studies have shown that intestinal flora disorders may be closely related to bone marrow suppression and impaired immune function after chemotherapy.Therefore,the quantitative analysis of intestinal flora of lung cancer patients before and after chemotherapy is helpful to understand the impact of chemotherapy drugs on intestinal flora from the perspective of microecology,and to provide a basis for the use of microecological regulators to prevent and treat intestinal flora disorders caused by chemotherapy,bone marrow suppression,immune function decline, chemotherapy-related gastroenteritis and other side effects.At present,the research of intestinal flora is mainly in the field of gastrointestinal tumors,and relatively few in the field of lung cancer.Objective: To explore the evolution of intestinal flora before and after chemotherapy in lung cancer patients and its relationship with adverse reactions to chemotherapy.To explore the feasibility of administering microbial preparations before chemotherapy to reduce the side effects of chemotherapy.Method:1.Collection of samples: Screening of 60 lung cancer patients who were treated at the hospital from July 2018 to November 2019,confirmed by pathology or cytology for 60 cases of lung cancer patients with lung cancer,all accept single drug or drug combination chemotherapy,including 37 cases with chemotherapy before and after the acquisition fresh dejection time,more than 23 cases for chemotherapy before collecting fresh dejection time,will match the gender,age of 17 cases of healthy people as control group,at the same time to collect control fresh dejection time,as soon as possible after collection in-80 ? refrigerator.Clinical information of enrolled patients was also collected.2.Extraction of sample DNA: The CTAB method was used to extract DNA from stool samples.3.Detection of DNA purity:(1)Analysis of DNA purity and integrity by agarose gel electrophoresis(AGE);(2)Qubit accurately quantifies DNA concentration.4.Construct a DNA library and perform Illumina Hi Seq sequencing.5.Analysis of results: species dilution,functional annotation and advanced functional analysis of gene sequences.Result:1.The number and types of intestinal flora in lung cancer patients were significantly lower than those in the control group,and the richness and diversity of the flora were decreased.From the level of the phylum,At the level of phylum,Firmicutes increased in abundance and Bacteroidetes and Proteobacteria decreased in abundance.Metastat analysis showed that the Numbers of Prevotella,Alistipes and Streptococcus decreased(p>,0.05),but the difference was not statistically significant.The number of Ruminococcus and Eubacteria was significantly increased(p <0.05),and the difference was statistically significant.2.Compared with that before chemotherapy,lung cancer patients after chemotherapy showed that the abundance of Firmicutes increased and the abundance of Bacteroides was decreased.From the perspective of genus level,the abundance of Ruminococcus,Eubacterium,Streptococcus,and Faecalibacterium genus increased,while the abundance of Bacteroides and Alistipes decreased.Metastat analysis revealed that the number of Streptococcus and Veillonella increased significantly compared with that before chemotherapy(p<0.05),and the difference was statistically significant.3.The abundance of Bacteroidetes increased and the Firmicutes decreased in patients with gastrointestinal reactions compared with those without.From the perspective of genus level,the abundance of Prevotella,Streptococcus,and Veillonella increased,while the abundance of Bacteroides,Eubacterium,and Alistipes decreased.Metastat analysis found that the number of Bacteroides,Prevotella,and Streptococcus was significantly higher than that of non-digestive reactions(p <0.05),and the number of Ruminococcus was decreased(p <0.05).Conclusion:1.The intestinal flora structure of patients with lung cancer is significantly different from that of healthy people,and the Eubacterium and Ruminococcus are significantly increased.2.After chemotherapy for lung cancer patients,the increase in Streptococcus and Veillonella may increase the risk of infection in patients.3.After chemotherapy for lung cancer patients,the increase of Bacteroidetes,Prevotella and Streptococcus had obvious correlation with digestive tract reaction.