Studies done on Japanese immigrants in the USA, Asian Jewish immigrants to Israel and East European immigrants in Australia have revealed that they acquire the common CRC rates in the country of their adoption. There is no doubt whatsoever which environmental factors, probably diet , may account for these cancer rates. Excessive alcohol consumption and cholesterol-rich diet are associated with a high risk of colon cancer [11,12]. A diet poor in folic acid and vitamin B6 is also associated with a higher risk of developing colon cancer with an overexpression of p53 . Eating pulses at least 3 times a week lowers the risk of developing colon cancer by 33%, after eating less meat, while eating brown rice at least once a week cuts the risk of CRC by 40%. These associations suggest a dose-response effect. Frequently eating cooked green vegetables, nuts and dried fruit, pulses and brown rice has been associated with a lower risk of colorectal polyps . High calcium intake offers a protector effect against distal colon and rectal tumours as compared with the proximal colon. Higher intake of dairy products and calcium reduces the risk of colon cancer . Taking an aspirin regularly after being diagnosed with colon cancer is associated with less risk of dying from this cancer, especially among people who have tumours with COX-2 overexpression . Nonetheless, these data do not contradict the data obtained on a possible genetic predisposition, even in sporadic or non-hereditary CRC.
Modifiable risk factors of CRC include smoking habit, physical inactivity, being overweight and obesity, eating processed meat and drinking alcohol excessively [17-19]. CRC screening programmes are possible only in economically developed countries. However, attention should be paid in the future to those geographical areas with ageing populations and a western lifestyle [20,21]. Sigmoidscopy screening done with people aged 55-64 years has been demonstrated to reduce the incidence of CRC by 33% and mortality by CRC by 43%.