Michael Reger

Ph.D., M.P.H.

Ferris State University

Assistant Professor

PLCO (Learn more about this study)

PLCO-353

Mar 8, 2018

Phytoestrogen intake and the risk of total and advanced colorectal cancer

Colorectal cancer is the third most common cancer diagnosed and the third leading cause of cancer-related deaths among men and women in the U.S (1). Non-modifiable risk factors have been established that increase the risk of colorectal cancer (age, race/ethnicity, and family history) (2); however, the identification of modifiable factors for colorectal cancer prevention would have a greater impact on the alleviation of the colorectal cancer burden. A factor not yet definitively explored is the intake of dietary phytoestrogens in the U.S. population and the resulting impact on colorectal cancer incidence and mortality.
Phytoestrogens are a group of non-steroidal plant metabolites that can induce biologic responses due to their structural similarity to 17β-estradiol and the resulting ability to bind to estrogen receptors (3). One of the principle classes of phytoestrogens is isoflavones, which are found mainly in soy products, legumes, and chickpeas (4). Isoflavones found in soy products include genistein, daidzein, and glycitein (5). Experimental studies have revealed that one of the health benefits associated with phytoestrogen intake include a lowered risk of certain types of cancer (6), but experimental evidence conducted using animal models suggesting an increased intake of phytoestrogens may decrease the risk of colorectal cancer have not been adequately explored. Experimental studies examining the relationship between phytoestrogen intake and other types of cancer, such as prostate cancer, have yielded mixed results, with some of these animal models showing a decreased risk of cancer (7), and others showing increased intake of the phytoestrogen genistein enhanced cell proliferation which suggests that phytoestrogens may play a role in the development of aggressive prostate cancer (8). To this point, few epidemiologic studies have examined the association between phytoestrogen intake and colorectal cancer risk, notably, the differences in risk of total colorectal cancer and advanced colorectal cancer with the association of phytoestrogen intake. A recently published epidemiologic study showed evidence that the dietary intake of certain phytoestrogens was associated with an elevated risk of advanced prostate cancer (9), which suggests that the relationship between phytoestrogens and other types of cancer needs further exploration.
The need is critical to explore the association between colorectal cancer and phytoestrogen intake. The establishment of an inverse association between colorectal cancer and increased phytoestrogen intake could open two new avenues of prevention: primary prevention of new possible colorectal cancer cases, and secondary prevention from slowing the rate of progression of latent colorectal neoplasms to more advanced cases of the disease. This approach is both feasible and cost-effective since increasing phytoestrogen levels can be accomplished simply through the consumption of soy-based products. Conversely, the establishment of an increased risk of advanced colorectal cancer and phytoestrogen intake could also decrease the burden of disease.