Smokers have a two-fold increased risk of developing colorectal polyps, the suspected underlying cause of most colorectal cancers (CRC), according to a new study.
The results from this meta-analysis showed pooled risk estimates of 2.14 for current versus never smokers, 1.82 for ever versus never smokers and 1.47 for former versus never smokers. Ever smokers had a 13 percent increasing risk of polyps for every additional 10 pack-years smoked in comparison to never smokers. For example, an individual who smoked one pack of cigarettes per day for 50 years or two packs a day for 25 years had almost twice the probability for developing colorectal polyps compared to an individual who never smoked.
The results of this meta-analysis suggest that approximately 20 percent to 25 percent of colorectal polyps may be attributed to smoking. Risk was significantly greater for high-risk polyps, indicating that smoking may be important for the transformation of polyps into cancer. The study findings are potentially important for determining the age of onset of colorectal cancer screening.
"While the harmful health effects of tobacco smoking are well known, smoking has not been considered so far in the stratification of patients for CRC screening. Our findings could support lowering the recommended age for smokers to receive colorectal cancer screening," said Albert B. Lowenfels, MD, senior author of the study, from New York Medical College, Valhalla, New York.
At present, evidence of a role for tobacco smoking on the development of CRC is still controversial. One explanation could be that CRC develops much later in life than polyps; the long latency period makes it difficult to establish a firm link between smoking and CRC.
The study was performed at the Division of Epidemiology and Biostatistics, European Institute of Oncology, Milan, Italy where the lead author, Edoardo Botteri, performed the analysis based on the combined evidence from 42 independent observational studies.
The study was recently published in Gastroenterology, the official journal of the American Gastroenterological Association (AGA) Institute.
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