Functional FEN1 genetic variants contribute to risk of hepatocellular carcinoma, esophageal cancer, gastric cancer and colorectal cancer

College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, China, Clinical Laboratory, Shandong Cancer Hospital, Shandong Academy of Medical Sciences, Jinan, Shandong Province, China, Department of Radiation Oncology, Huaian No. 2 Hospital, Huaian, Jiangsu Province, China and Department of Gynecologic Oncology, Shandong Cancer Hospital, Shandong Academy of Medical Sciences, Jinan, Shandong Province, China