[A Prospective Cohort Study on Soy Product Intake and the Risk of Lung Cancer 
Based on Shanghai Suburban Adult Cohort and Biobank].

BACKGROUND: Lung cancer is one of the malignant cancers with the highest incidence rate, and it is important to identify the factors contributing to lung cancer carcinogenesis for prevention. Lifestyle and genetic factors play important roles in cancer development, however the impact of dietary factors, such as soy product intake, on lung cancer risk remains inadequately understood. This study aims to explore the associations between soy product intake, genetic risk, and lung cancer incidence, and validate the consistent effects of soy product intake in European populations, thereby providing new insights for lung cancer prevention. METHODS: Utilizing the Shanghai Suburban Adult Cohort and Biobank (SSACB) (n=66,311), Cox proportional hazards model was adopted to assess the association between soy product intake and lung cancer incidents, followed by subgroup analyses stratified by gender, smoking status, and pathological types of lung cancer. The UK Biobank (UKB) was used for validation of the effect of soy product intake on lung cancer. To investigate the association between genetic factors and lung cancer, in addition to previously reported loci, we incorporated newly identified loci from two independent studies in Southeast China: a nested case-control population from the SSACB cohort (433 cases/650 controls) and a case-control study from the Shanghai Cancer Center-Taizhou cohort (1359 cases/1359 controls). Meta-analysis and Linkage disequilibrium clumping (LD clumping) of the association results identified 23 loci for polygenic risk score (PRS) construction. Subsequently, conditional Logistic regression model was used to assess the association between genetic risk and lung cancer. RESULTS: In SSACB cohort, after adjusting for age, gender, smoking, chronic bronchitis, body mass index (BMI), vegetable intake and red meat intake, sufficient soy product intake was significantly associated with a reduced risk of lung cancer [hazard ratio (HR)=0.60, 95%CI: 0.47-0.77, Padj=6.69E-05], an effect that was consistent in males and females, smokers and non-smokers. In UKB, although the association did not reach statistical significance, a protective trend against lung cancer was also observed (HR=0.76, 95%CI: 0.55-1.06, Padj=0.10). In the nested case-control population within SSACB, a PRS score generated in the Chinese population was significantly correlated with lung cancer risk. After adjustment of age, gender, smoking, chronic bronchitis, and soy product intake, the high-PRS group had a 1.88 times higher risk of lung cancer compared to the low-PRS group (Padj=1.84E-03). CONCLUSIONS: The prospective cohort study found that adequate intake of soy products was significantly associated with a reduced risk of lung cancer, while a high PRS is a risk factor for lung cancer development. Integrating soy product intake and PRS into traditional epidemiological risk factor prediction will guide personalized lung cancer prevention and high-risk population stratification.