Dietary factors affecting colorectal cancer - Thesis Example

About two-thirds of the new cases of large bowel cancer registered in the UK in 2008 related to malignancy in the colon and one-third in the rectum (Office for National Statistics, 2011).            A study reviewing the long-term incidence data collated from 51 cancer registries worldwide covering a period of 20 years by the International Agency for Research on Cancer (IARC) has found an increase in the colorectal cancer incidence rates for both males and females in 27 of 51 countries worldwide between 1983 and 2002.

The increase was especially apparent in economically transitioning countries such as Eastern European countries, most parts of Asia, and some countries of South America (Center et al., 2009). In fact, the study found the incidence rates among men in the Czech Republic and Slovakia to surpass the highest incidence observed in the United States and other developed nations. However, in the USA, after registering an increase until the mid-1980s, incidence rates in the last two decades have shown a decline in the case of both men and women (National Cancer Institute, 2011).

           Colorectal cancer (CRC) or cancer of the large bowel occurs in the colon or rectum. The ICD code (International Classification of Disease coding system set by the World Health Organisation), tenth revision, for colorectal cancer is ICD10 C18-21.  As shown in Fig. 1, the large intestine comprising the end of the long, coiled, tubular digestive tract located in the abdomen is the colon, and the passage connecting colon to the anus is the rectum.

The basic function of the colon is solid waste processing. Fig. 1. Diagram showing the location of the large intestine or colon, small intestine, rectum and anus. (Source: Centers for Disease Control and Prevention, http://www.cdc.gov/cancer/colorectal/basic_info/index.htm) Based on the location of the tumour in the proximal or distal segments of colon, two distinct categories of colon cancer are identified. Several morphological and physiological differences exist between right and left colon which are reflected in the incidence of right and left colon cancers (Weisburger, 1991).

The right and left colon cancers are believed to be influenced by specific environmental, genetic, and molecular factors (Bufill JA., 1990). According to the CancerStats Monograph 2004 (Cancer Research UK), significantly more tumours are diagnosed in the left side of the bowel with nearly 60% of tumours presenting themselves in the sigmoid colon, rectosigmoid junction and rectum. Figure 2 depicts the percentage distribution of tumours observed within the large bowel in Great Britain between 2006 and 2008. Fig. 2.

Percentage distribution of cancer cases within the large bowel in Great Britain during 2006-2008. (Source: http://info.cancerresearchuk.org/cancerstats/types/bowel/incidence/#source1) The occurrence of CRC has been observed to be strongly related to age with 86% of cases arising in people who are 60 years plus (Office for National Statistics, 2011; ISD Scotland, 2010; Welsh Cancer Intelligence and