Phytochemicals and cancer chemoprevention

The unending morbidity and mortality that results from cancer, as well as adverse reactions due to chemotherapy and the enormous economic burden of treatment and hospitalization, advocates for the necessity of chemopreventive measures. Cancer chemoprevention refers to the use of agents capable of reversing, reducing, or slowing down the pathology of cancer at various stages. Fortunately, a few therapeutic drugs with relatively low toxicity (e.g., tamoxifen, finasteride), and a sparse number of vaccines (hepatitis B, HPV), are used to prevent specific cancers. In the general population, however, therapeutic options for cancer prevention are not common. Nonetheless, it is generally agreed that diet affects the genesis of cancer, and phytochemicals have the capacity of functioning as cancer chemoprevention agents. This is supported by epidemiological studies and clearly documented with animal models designed to mimic human carcinogenesis. Additionally, some public health strategies, such as recommendations for greater consumption of fruits and vegetables, reflect the merits of cancer chemoprevention. Here, we focus on some well- established natural product cancer chemopreventive agents, including resveratrol (grapes), epigallocatechin-3-gallate (green tea), sulforaphane (cruciferous vegetables), anthocyanins (grapes and berries), curcumin (turmeric), silibinin (milk thistle), and lycopene (tomatoes). As aptly demonstrated by genomic analysis and other methods, the mechanistic underpinning is variable and complex. In addition, responses may be mediated through indirect mechanisms, such as interaction with the microbiome. Furthermore, ancillary applications of chemopreventive agents are worthy of consideration, such as management of sequelae induced by chemotherapy. Recognizing the loss of millions of cancer patients every year, it is obvious that negating malignant metastatic conditions remains of paramount importance. In meeting this objective, cancer chemoprevention offers great promise.