The formation time of duodenal cancer can range from several years to several decades, and the specific time should be analyzed with different groups of people. Duodenal cancer is an intestinal malignant tumor with low incidence rate, and the occurrence of the disease is related to many factors, such as not paying attention to healthy diet, i.e. more fine pasta, lack of crude fiber food, etc.; smoking; age older than 50; gender, i.e. males are more prone to develop duodenal cancer than females; and suffering from hyperpigmented polyposis, familial adenomatous polyposis, etc.. Therefore, if there is a greater correlation with the risk factors of duodenal cancer, the time of developing cancer may be faster, which may be a few years; on the contrary, it may be decades. Regular medical checkups and staying away from high-risk factors in daily life can effectively reduce the risk of cancer.