Berries and other natural products in pancreatic cancer chemoprevention in human clinical trials

Pancreatic ductal adenocarcinoma (PDAC) was the 12th and 11th most common cancer in men and women worldwide in 2012, with the highest incidence in North America and Europe and the lowest in Africa and Asia. Due to the lack of efficient early diagnosis and rapid disease progression, PDAC patients have a 5-year survival rate of just 5%. Epidemiological studies suggest that smoking, obesity, type II diabetes, and pancreatitis are common risk factors for PDAC development. By contrast, high intake of fresh fruit, vegetables, and nuts rich in phytochemicals could reduce PDAC risk. This review summarizes the human clinical studies that have used berries or other natural products for chemoprevention of PDAC. Developing chemopreventive agents against PDAC would be tremendously valuable for the high-risk population and patients with premalignant lesions. Although some clinical trials of these agents have been completed, most are in early phases, and the results are not promising, which may be due to administration of the natural products at advanced stages of PDAC. Thus, further mechanistic studies using genetic animal models that recapitulate the tumor microenvironment and immunology of human PDAC would be informative for selecting an effective window for intervention with berries or other natural compounds.