Clinical Medical Care As a senior expert in gastroenterology, Professor Fang is rigorous in scholarship, noble in medical ethics and teaching ethics, and highly skilled in medical practice. Even now, he insists on weekly outpatient, endoscopy, and ward work, treating more than 9,000 patients annually, and particularly excels in the diagnosis, treatment, and prevention of gastrointestinal cancers and their precancerous diseases. In 2024, he was awarded the Shanghai "Model of Medical Ethics," and in 2015, he was named a National Advanced Worker (Model Worker). Scientific Research Gastric cancer is one of the malignant tumors with high incidence and mortality worldwide, and the main precancerous disease of gastric cancer is chronic atrophic gastritis. The incidence of colorectal cancer in Shanghai has continued to rise at an annual rate of 4.2%, jumping to the second position, while the proportion of early diagnosis is less than 10%; colorectal cancer mainly arises from adenomas. Professor Fang Jingyuan was the first to confirm that gastrointestinal microbiota can be used for the early diagnosis and prognosis prediction of gastric cancer and colorectal cancer, and proposed new diagnostic ideas and methods: he found that high levels of Streptococcus constellatus, etc. in feces are high-risk factors for the occurrence of gastric cancer (Gastroenterology 2022). He was the first to confirm that Fusobacterium nucleatum can be used to determine chemotherapy resistance and prognosis after colorectal cancer surgery (Cell 2017, cited more than 1,100 times, with a commentary in the same issue). This laid an important foundation for the early diagnosis and prognosis prediction of colorectal cancer and for the development of precise warning markers and prevention and treatment targets. He also found that high content of this bacterium indicates failure of PD-1 antibody immunotherapy (Cell Host Microbe 2023). He innovatively proposed new viewpoints on the use of traditional drugs to treat gastrointestinal precancerous diseases and block cancer progression and elucidated the mechanisms, providing new strategies and means for the primary prevention of gastrointestinal cancers: a multicenter RCT study found that folic acid prevents the initial occurrence of colorectal adenoma; he confirmed that berberine reduces adenoma recurrence and thus prevents colorectal cancer (Lancet GH 2020), which was commented on by experts in the same issue and cited by clinical guidelines. He proposed that the mechanism by which statins prevent colorectal cancer is related to increasing Lactobacillus reuteri (Nat Microbiol 2023). He further analyzed the mechanisms of gastrointestinal cancer occurrence: he elucidated that epigenetic disorders and activation of proliferation signaling pathways promote the occurrence and development of gastrointestinal cancers (Cancer Discov 2016, with a commentary in the same issue; Lancet Oncol 2005, cited more than 1,000 times). Bifidobacterium-secreted urease can reduce the urea cycle, thereby inhibiting M2 polarization of macrophages, reducing polyamines, and blocking the occurrence of colorectal cancer (Cell Metab 2023; featured recommended paper). As an independent or last corresponding author, he has published 195 SCI papers and received 15 special commentaries; 2 papers were cited by the 11th edition of the classic American textbook Sleisenger and Fordtran's Gastrointestinal and Liver Disease (2021). He has been selected for 5 consecutive years as an "Elsevier" Highly Cited Chinese Researcher and in 2023 as a "Clarivate" Global Highly Cited Researcher. He has applied for and obtained 9 authorized national invention patents; among them, one patent related to fecal bacteria for screening gastric cancer has been successfully transferred to an enterprise, and a kit is being developed.