Dietary plants for oral cancer prevention and therapy: A review of preclinical and clinical studies.

Oral cancer is a disease with high mortality and rising incidence worldwide. Although fragmentary literature on the anti-oral cancer effects of plant products has been published, a comprehensive analysis is lacking. In this work, a critical and comprehensive evaluation of oral cancer preventative or therapeutic effects of dietary plants was conducted. An exhaustive analysis of available data supports that numerous dietary plants exert anticancer effects, including suppression of cell proliferation, viability, autophagy, angiogenesis, invasion, and metastasis while promoting cell cycle arrest and apoptosis. Plant extracts and products target several cellular mechanisms, such as the reversal of epithelial-to-mesenchymal transition and the promotion of oxidative stress and mitochondrial membrane dysfunction by modulation of various signaling pathways. These agents were also found to regulate cellular growth signaling pathways by action on extracellular signal-regulated kinase and mitogen-activated protein kinase, inflammation via modulation of cyclooxygenase (COX)-1, COX-2, and nuclear factor-κB p65, and metastasis through influence of cadherins and matrix metalloproteinases. In vivo studies support these findings and demonstrate a decrease in tumor burden, incidence, and hyperplastic and dysplastic changes. Clinical studies also showed decreased oral cancer risk. However, high-quality studies should be conducted to establish the clinical efficacy of these plants. Overall, our study supports the use of dietary plants, especially garlic, green tea, longan, peppermint, purple carrot, saffron, tomato, and turmeric, for oral cancer prevention and intervention. However, further research is required before clinical application of this strategy.