There are stark geographical contrasts in the incidence of colon cancer worldwide. The new study analyses the causes of these disparities, starting with Spanish trends between 1951 and 2006 in terms of certain changes in consumption (tobacco, alcohol, red and processed meat, fish, vegetables...) and also behaviour (physical exercise, sedentary lifestyles).
The results, published in the European Journal of Cancer Prevention, show that mortality due to colon cancer increased between 1951 and 2000 in both sexes. The positive finding is that between 2000 and 2006 the number of deaths stabilised in men and decreased in women.
"Through the second half of the twentieth century many industrialised countries saw reductions in incidence and mortality rates and, in some cases, countries who previously experienced rates as high as Spain now have lower levels. The most striking phenomenon is the unstoppable increase in the incidence in men and women", Luis Mara Bjar, main author of the study and researcher at the University of Seville, explains to SINC.
Colon cancer has the second-highest incidence and mortality rate of any tumour in Spain, behind lung cancer for men and breast cancer for women. In 2006, 13,101 people died from colon cancer in Spain, constituting 12.9% of the total deaths from cancer in that year.
What is behind these differences?
Several exposure factors associated with behaviour can explain these trends, primarily the consumption of tobacco and alcohol. "In Spain, per capita consumption of cigarettes in the period 1960-2006 shows a substantial increase until the end of the '80s, followed by a significant reduction in subsequent years, with consumption stabilising from the late '90s", states Bjar.
"As in many other countries, the price of cigarettes in relation to income has determined consumption. However, regional and state governments have been inexplicably backward when it comes to implementing legislative measures to increase taxes on tobacco", remarks the expert.
Scientific evidence gathered from an extensive number of epidemiological studies shows that smoking increases the risk of developing colorectal polyps and colon cancer. Today, the percentage of colon cancer in the population attributable to tobacco use is between 12 and 21%.
Moreover, alcohol consumption increased until the early '80s, then gradually declined. Data available in Spain show that the prevalence of considerable consumption of alcohol in the period 1951-2006 was greater among men.
The authors do point out, however, that Spain has one of the lowest average relative alcohol prices in Eastern Europe, and consumption levels have remained among the highest in the world in recent decades.
"The risk relationship between alcohol consumption and colon cancer is obvious in men and women, with a dose-effect ratio, especially where consumption exceeds 30 g/day", explain the experts. According to the study, the percentage of colon cancer in the population caused by alcohol consumption is 0.9% in women and 5% in men.
"There is an urgent need in Spain to apply more decisive legislation and educational measures to counteract smoking, excessive alcohol consumption, consumption of red meat, sedentary lifestyles and the other factors analysed", concludes Bjar.
"The Government spends thousands of millions of Euros on treating chronic diseases, but promoting a healthier lifestyle would generate greater benefits", claims the research team.
FECYT - Spanish Foundation for Science and Technology