Lung cancer has the highest incidence and mortality of any cancer in the world. In recent years, with the development of microbial detection technology, the intratumor microbiota has gradually become a hot spot and frontier in the field of lung cancer research. Studies have found that the microbiota present in tumors can influence the development of lung cancer in a variety of ways. In addition, the intratumor microbiota can be used as a potential biomarker for the diagnosis and prognosis assessment of lung cancer, and the regulation of the intratumor microbiota of lung cancer is expected to become a new type of lung cancer treatment. In this paper, we reviewed the latest research progress on the relationship between intratumor microbiota and lung cancer, summarized the origin and characteristics of intratumor microbiota, discussed the mechanism of its influence on the occurrence and development of lung cancer, and explored its potential applications in the diagnosis, treatment and prognosis of lung cancer.
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Humans ; Lung Neoplasms/diagnosis* ; Microbiota ; Animals ; Prognosis

Objective:To evaluate the possible mediation effect of smoking and healthy diet score on the association between educational level and the risk of lung cancer incidence.Methods:After excluding individuals with missing educational levels and cancer information at baseline, 446?772 participants in the UK Biobank (UKB) prospective cohort study were included. Cox regression models were used to investigate the associations of educational level and smoking and healthy diet score with the incidence of lung cancer. Mediating effect analysis was conducted to analyze the mediating effect of smoking and healthy diet score on the correlation between educational level and lung cancer.Results:During a median follow-up of 7.13 years, 1?994 new- onset lung cancer cases were observed. Per 1 standard deviation (5 years) increase in educational level was associated with a 12% lower risk of lung cancer ( HR=0.88, 95% CI: 0.84-0.92). The corresponding level 1-5 in the International Standard Classification for Education (ISCED) were mapped to UKB self‐report highest qualification to estimate the educational level. A higher rank means a higher educational level. Compared with level ISCED-1, the HR(95% CI) of level ISCED-2, ISCED-3, ISCED-4 and ISCED-5 were respectively 0.83 (0.72-0.94), 0.67 (0.53-0.85), 0.76 (0.65-0.89) and 0.72 (0.64-0.80) for lung cancer. Education years were negatively correlated with smoking, with β coefficients (95% CI) being -0.079 (-0.081- -0.077), but positively correlated with healthy diet score ( β=0.042, 95% CI: 0.039-0.045). Analysis of mediating effect indicated that the association of educational level with lung cancer risk was mediated by smoking and healthy diet score, the proportions of mediating effect were 38.952% (95% CI: 31.802%-51.659%) and 1.784% (95% CI: 0.405%-3.713%), respectively. Conclusion:Smoking and healthy diet score might mediate the effect of educational level on the incidence of lung cancer, indicating that improving the level of education can reduce the risk of lung cancer by changing lifestyles such as smoking and diet.

Objective:To explore how to personalize lung cancer screening programs for prevention in Chinese populations based on individual genetic risk score.Methods:We constructed the lung cancer polygenic genetic risk score (PRS-19) based on the 19 previously published genetic variations, using 100 615 participants with genotyping data from the China Kadoorie Biobank (CKB). Using the 5-year absolute risk of lung cancer in a population (55 years old with at least 30-pack-year history of smoking) as reference, the trend of 5-year absolute risk in different genetic risk groups was calculated in smokers and non-smokers, respectively. Distribution curves of 5-year absolute risk were also described to determine the theoretical age or smoking dose when different genetic risk groups reached the reference values. Given the overall findings, the specific start age for lung cancer screening were suggested for different genetic risk groups.Results:The 5-year absolute risk of lung cancer was 0.67% in 55-year-old smokers with 30 packs per year in the CKB. Among smokers, 5-year absolute risk of participants increased as the genetic risk increased. Hence, it was recommended that people at high genetic risk should start screening earlier. For the highest genetic risk populations (the top 1% of PRS), the start age might be changed to 50 years old. If the start age remained at 55-year-old, the smoking dose should be set lowered in high genetic risk populations. For the highest genetic risk populations, they should be included in lung cancer screening regardless of the cumulative smoking exposure. Among nonsmokers, it was also valuable to screen people with high genetic risk, considering the start age of 62 for the highest genetic risk populations and 74 for the lowest genetic risk populations (the bottom 5% of PRS).Conclusions:PRS-19 can be effectively used in developing lung cancer screening program for individualized prevention in China. For smokers with high genetic risk, the recommended starting age and smoking dose could be lowered for lung cancer screening, and non-smokers with high genetic risk could also be included in the screening programs.