Study: Smoking Raises Colon Cancer RiskDec 18, 2008 | Parker Waichman LLP A recent analysis of a variety of earlier studies—a meta-analysis—has revealed a “significant” link between smoking and an increased risk for colorectal cancer and death, Science Daily is reporting. Science Daily notes that tobacco was the cause of about 5.4 million deaths in 2005, yet there are still about 1.3 billion smokers, worldwide. Health Day News reported that smoking increases the risk of CRC by about 18 percent, with a 25 percent increased risk of death, according to the study, which was published in the December 17 issue of the Journal of the American Medical Association (JAMA).
Up until now, an array of cancers have been clearly linked to smoking; this was not always the case with smoking and colorectal cancer—also known as CRC—due to inconsistent study outcomes, notes Science Daily. "Because smoking can potentially be controlled by individual and population-related measures, detecting a link between CRC and smoking could help reduce the burden of the world's third most common tumor, which currently causes more than 500,000 annual deaths worldwide. In the United States alone, an estimate of approximately 50,000 deaths from CRC would have occurred in 2008," the authors write, quoted Science Daily. Study author Edoardo Botteri, M.Sc., of the European Institute of Oncology, Milan, Italy, and colleagues conducted the meta-analysis, said Science Daily, in order to review and summarize published data that looked at the link between CRC and death to smoking.
Science Daily said the team identified 106 observational studies, with analysis based on about 40,000 new CRC cases and, said Botteri, according to Health Day News, "There was an increase in risk with increasing number of cigarettes per day and pack-years—the number of packs of cigarettes smoked per day multiplied by years of consumption."
Also, said Science Daily, 17 studies were used to review mortality and revealed an increase in CRC death correlating to an increased number of cigarettes smoked daily and for longer duration of smoking. For CRC and death, the association increased for rectal over colon cancer. “Smoking has not been considered so far in the stratification of individuals for CRC screening. However, several studies reported that CRC occurs earlier in smokers, particularly in those with heavy tobacco consumption, and our previous and present findings provide strong evidence of the detrimental effect of cigarette smoking on the development of adenomatous [benign tumor] polyps and CRC. We believe that smoking represents an important factor to consider when deciding on the age at which CRC screening should begin, either by lowering the age in smokers or increasing the age in non-smokers," the authors wrote, quoted Science Daily. The studies reviewed consisted of from small trials with just a few hundred to large trials consisting of over one million participants, said Health Day News.
Botteri also noted, said Health Day News, that, "Smoking is significantly associated with colorectal cancer incidence and mortality. People should be aware that smoking increases the risk of cancer not only in organs where there is direct contact with tobacco-related carcinogens, such as lung, oropharynx, larynx, and upper digestive tract, but also in organs where exposure to tobacco degradation products is indirect, such as the pancreas, kidney, bladder, cervix, colon and rectum." Tobacco is responsible for about 100 million deaths during the past century and 80 percent of lung cancers are directly linked to smoking, reports the study, said Health Day News.