Therapeutic effects of natural polyphenols on colorectal adenomas: Focus on preclinical studies (Review)

Colorectal adenoma (CRA) is a premalignant lesion of colorectal cancer. The current treatment is surgical resection, but CRA is prone to recurrence, and there is no safe and effective drug to prevent adenoma recurrence and canceration. Recent studies have shown that natural compounds in plants have favorable antitumor effects. According to preclinical studies, natural polyphenols can regulate different signal pathways and targets to play a role in the treatment of CRA, which is closely related to its inhibition of proliferation, induction of apoptosis, inhibition of inflammation and oxidative stress, and regulation of intestinal flora. Natural polyphenols are potential candidates for CRA therapy due to their remarkable efficacy and safety. In the present review, attention was paid to the experimental research progress of natural polyphenols extracted from numerous plants in the treatment of CRA in the last 10 years. The present review provided new guidance for the study of CRA, clarified the therapeutic role of polyphenols in CRA, and evaluated for the first time, to the best of our knowledge, the therapeutic potential of natural polyphenols to treat CRA by targeting multiple genes and signal pathways and epigenetic modification.