Colorectal Cancer and the Relationship Between Genes and the Environment

Abstract

Colorectal cancer (CRC) is a significant cause of morbidity and mortality in developed countries, with both genetic and environmental factors contributing to the etiology and progression of the disease. Several risk factors have been identified, including positive family history, red meat intake, smoking, and alcohol intake. Protective factors include vegetables, calcium, hormone replacement therapy, folate, nonsteroidal anti-inflammatory drugs, and physical activity. The interaction between these environmental factors, in particular diet and genes, is an area of growing interest. Currently, oncogenes, tumor suppressor genes, and mismatch repair genes are believed to play an essential role in colorectal carcinogenesis. When considering the genetics of CRC, only 10% of cases are inherited and only 2-6% can be ascribed to the highly penetrant genes, such as APC, hMLH and hMSH2. Lower penetrance genes combined with a Western-style diet contribute to the majority of sporadic CRCs. The purpose of this article is to give a brief overview of the epidemiologic studies that have been conducted and present the major findings. Here, we examine the molecular events in CRC, with particular focus on the interaction between genes and environment, and review the most current research in this area.

Colorectal cancer: case-control study of sociodemographic, lifestyle and anthropometric parameters in Riyadh

“…Global geographic variations in incidence of colorectal adenoma and cancer are thought to be due to multiple factors: sociodemographic, lifestyle, environmental and genetic. Hereditary factors play a definite role, but gene-environment interactions are also important in the pathogenesis [11]. Approximately 70% of the risk of colorectal cancer can be related to environmental factors, and identification of these may help prevent the development of the disease [12].…”

Effects of Dietary Counseling on Patients with Colorectal Cancer

“…Colorectal cancer is second in global cancer incidence and it is the most common cause of cancer death among non-smokers. US and EU incidence figures exceed global averages, which is consistent with an increased risk in industrialized nations (2). Factors associated with increased risk of colorectal cancer are host susceptibility and a sequence of different carcinogenic exposures.…”

“…The incidence and mortality rates for cancers of the colon and rectum are among the highest of all malignancies worldwide (1,2). Colorectal cancer is second in global cancer incidence and it is the most common cause of cancer death among non-smokers.…”

“…Cancer anorexiacachexia syndrome is highly prevalent among patients with colorectal cancer, and has a large impact on morbidity and mortality, and on patient quality of life. Early intervention with nutritional supplementation has been shown to halt malnutrition, and may improve outcome in some patients (2). The etiology of cancer-associated malnutrition appears to be related to the pathological loss of inhibitory control of catabolic pathways, whose increased activities are not counterbalanced by the increased central and peripheral anabolic drive (3).…”

Exploration and forecasting of behaviours and factors relating to fruit and vegetable intake among seniors in the community

“…Most of these are highly correlated to dietary habits (4)(5)(6) . Fruits and vegetables are rich in nutrients like vitamin C, vitamin E, carotene, folic acid, minerals and edible fibre, and eating them can significantly reduce the occurrence of the above-mentioned chronic diseases (7,8) , the metabolic syndrome (9) and cancer (10,11) .…”