A number of studies have shown that smoking ups colon
cancer risk. For example, a study published recently in the Journal of
Clinical Oncology reported that smoking was significantly associated with
shorter DFS (disease free survival) rates and TTR (time to recurrence) rates in
patients with colon cancer
. These adverse relationships were most evident
in patients with BRAF wild-type or KRAS mutated colon cancer.
Another study published in the
journal Clinical Gastroenterology and Hepatology revealed that smoking for at
least 20 years was associated with a 26 percent increase in risk of colorectal
cancer, compared with never smokers, and smoking 20g tobacco or more each day
was associated with a 30 percent increase in risk.
An earlier study from the Cancer
Research Center of Hawaii, University of Hawaii, even suggested that there
could be a difference in risk with the type of tobacco product. Non-filtered
cigarettes increased risk of both colon and rectal cancer, whereas filtered
cigarettes seemed to increase risk of rectal but not colon cancer. 'The
effect of smoking was not limited to the distant past, and accumulated
pack-years of smoking seemed to be more important than the time in which
, said the researchers of the study.
The present study however
represents the largest of its kind to demonstrate the link between smoking and
colon cancer. It is also the first to show that 'while the risk is increased in
both men and women, it is most pronounced in women smokers'.
'Our study is the first that
shows women who smoke less than men still get more colon cancer,' said Inger
Torhild Gram from the Department of Community Medicine, University of Tromsø,
Gram and her colleagues followed
602,242 participants aged 19 to 67 years at enrollment in 1972-2003, by linkage
to national registries through December 2007. Sixty three percent of the
participants were ever-smokers (59 percent women and 67 percent men).
During the follow up of 14 years,
the results were interesting - •
A total of
3,998 participants comprising 46 percent women developed colon cancer. •
ever-smokers had a 19 percent and male ever-smokers an 8 percent increased risk
of colon cancer compared with never smokers. •
started smoking when they were 16 or younger and women who had smoked for 40
years or more had an increased risk of about 50 percent, compared with
never-smokers and almost about 48 percent compared to men who smoked. •
men who smoked, women ever-smokers those who smoked 20 or more cigarettes daily
were 28 percent more likely to get cancer; and those who smoked 20 or more pack
years were 33 percent more likely to develop colon cancer as against men. •
ever-smokers had a significantly increased risk of 31 percent for proximal
colon cancer when determined on the basis of location of the cancer.
Smoking is associated with ﬂat
colorectal adenomas located mainly in the proximal colon and 'which is exactly
where we found them more often in women,' said Gram.
'The study, which is just getting
underway, is using data from the University's multiethnic cohort, so will also
reveal whether the findings apply only to Caucasians or to other ethnicities as
well,' she added.
The findings thus send a clear
message - Quit smoking!