Risk Factors for Colon Cancer - Research Paper Example

In most cases a combination of inhibitors is necessary to maximize the efficacy of the drug treatment. The possible side-effects associated with these drugs is still under investigation. Thus at present the prognosis for colon cancer associated with obesity has been found to be poor, however the combinational use of inhibitors could change the current prognosis. Keywords: colon cancer, obesity, insulin, adipokines According to recent surveys colon cancer is the third most commonly occurring cancer in males and second in the case of females associated with a mortality rate of 608,700 (Chen, 2012). About 1.2 million people are diagnosed with this type of cancer every year (Whitlock, Gill, Birch, & Karmali, 2012).

There are many causative factors involved in the pathogenesis of colon cancer which include environmental factors such as a high-fat/ low-fiber dietary intake, genetic factors such as inherited or cellular genetic mutations, life style changes such as smoking, physical inactivity and obesity (Chen, 2012; Ma, Yang, Wang, Zhang, Shi, Zou, & Qin, 2013). Studies have shown a strong link between obesity and the incidence of colon cancer. Obesity, which is measured as the body mass index, is on a rise over the past few decades all over the world.

The World Health Organization estimates show that about 10% of the world population is clinically obese (Whitlock, Gill, Birch, & Karmali, 2012). Obesity is associated with an increased risk of type II diabetes, hypertension, hyperlipidemia and heart disease. These conditions increase the serum levels of cancer risk factors such as insulin, insulin-like growth-factor 1 (IGF-1), leptin, interleukin-6, 17 (IL-6, IL-17), tumor necrosis factor alpha (TNF-alpha) and decreases serum levels of adiponectin which is considered to indirectly protect against cancer (Chen, 2012; Van Kruijsdijk, van der Wall, & Visseren, 2009).

The role of insulin and IGF-1 in the carcinogenic process has been supported by clinical studies. These factors in turn activate multiple signal pathways which can induce tumor growth. For example increased secretion of insulin and IGF-1 stimulate cancer growth by binding to their specific receptors and activate pathways that inhibit apoptosis and stimulate cell proliferation. IGF-1 stimulates the proliferation of cells by activating the signal pathways phosphatidylinositol 3-kinase and Ras/Raf mitogen activated protein kinase systems and signal transducer and activator of transcription 3 pathways (STAT 3).

IGF-1 is also involved in cell migration and invasion which favors cancer progression and metastasis (Chen, 2012; Van Kruijsdijk, van der Wall, & Visseren, 2009; Frezza, Wachtel, & Chiriva-Internati, 2006). Adipose tissue dysfunction in obese individuals plays a major role in promoting carcinogenesis by affecting important biochemical mechanisms such as insulin resistance, and production of adipokines and cytokines involved in inflammation. An increased leptin level which is secreted by the adipocytes in obese individuals is associated with the growth and proliferation of cancer cells.

The leptin hormone is known to promote mitogenesis, angiogenesis, and inflammation and inhibit apoptosis (Van Kruijsdijk, van der Wall, & Visseren, 2009; Frezza, Wachtel, & Chiriva-Internati, 2006). Obesity is also associated with decreased levels of adipone