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| Colorectal Cancer Shown to be a Smoking-Related Cancer |
| American Cancer Society Study Links 12% of Colorectal Cancer Deaths to Cigarettes |
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Atlanta 2000/12/05 -In the largest prospective study of cigarette smoking and colorectal cancer mortality, American Cancer Society staff researchers report finding strong evidence for classifying cancers of the colon and rectum as, in part, smoking-related.
An analysis of the Society’s Cancer Prevention Study II, detailed in an article in the December 6th edition of the Journal of the National Cancer Institute, concludes that not only is long-term cigarette smoking associated with an elevated risk for dying of this cancer, it estimates that about 12% of the l997 deaths from colorectal cancer may be attributable to cigarette smoking.
Ann Chao, PhD, Michael J. Thun, MD, and colleagues at the American Cancer Society report that colorectal death rates were highest among current smokers and lowest among those who never smoked.
"Clear benefits were also observed among those people who had quit smoking; the longer ago the higher the benefit, "said Dr. Chao.
Male current smokers had a 32% higher death rate than non-smokers in the study, and current female smokers had a higher death rate of 41%. The higher death rates increased with duration of their habit and with the number of cigarettes smoked daily.
The rates were higher for current smokers who began smoking cigarettes at younger ages, than those who smoked longer and more cigarettes per day.
Cancer Prevention Study II began enrolling approximately one million Americans in l982. Dr. Chao and her co-authors analyzed data on 312,332 men and 469,019 women from CPS II, among which 4,432 died from either colon or rectal cancer.
Data from these participants were controlled for a number of potentially confounding variables including alcohol use, physical activity, family history of colorectal cancer, vitamin use, and dietary factors.
"The size of the study allowed us to examine, in detail, gradients in smoking behavior separately in former and current smokers," said Dr. Chao.
"It also permitted us to estimate the percentage of smoking related colorectal cancer deaths in the general population, which would have been about 12 percent in l997, or more than 6,800 people for that year," she emphasized.
"The smoking epidemic in women began decades later than in men," said Michael J. Thun, MD, Vice President Epidemiology and Surveillance Research for the American Cancer Society.
"This may explain in part why the trends in colorectal cancer incidence and death rates differed between genders during the ‘50s, ‘60s and ‘70s with male rates being higher than female rates. As the smoking rates increased for women, the colorectal rates became very similar for both genders," explained Dr. Thun.
The American Cancer Society is the nationwide community-based voluntary health organization dedicated to eliminating cancer as a major health problem by preventing cancer, saving lives and diminishing suffering from cancer, through research, education, advocacy and service.
For information about cancer, call toll-free anytime 1-800-ACS-2345.
Joann Schellenbach
National Director Media Relations
American Cancer Society
212-382-2169
jschelle@cancer.org
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