- Smokers of both genders had increased risk for colon cancer compared with never-smokers.
- The risk increase was greater for female smokers.
- The more and longer a woman smoked, the greater her risk.
“Globally, during the last 50 years, the number of new colon cancer cases per year has exploded for both men and women,” said Inger Torhild Gram, M.D., Ph.D., professor in the Department of Community Medicine at the University of Tromsø in Norway. “Our study is the first that shows women who smoke less than men still get more colon cancer.”
Gram and her colleagues examined the association between cigarette smoking and colon cancer, by tumor location, in a large Norwegian cohort of more than 600,000 men and women. The participants from four surveys initiated by the National Health Screening Service of the Norwegian Institute of Public Health had a short health exam and completed questionnaires about smoking habits, physical activity and other lifestyle factors. The participants were followed by linkage to the Cancer Registry of Norway and the Central Population Register. During an average 14 years of follow-up, close to 4,000 new colon cancer cases were diagnosed.
Gram and colleagues found that female smokers had a 19 percent increased risk compared with never-smokers, while male smokers had an 8 percent increased risk compared with never-smokers.
In addition, women who started smoking when they were 16 or younger and women who had smoked for 40 years or more had a substantially increased risk, by about 50 percent. Also, the dose-response association between the number of cigarettes smoked per day, number of years smoked and number of pack-years smoked and colon cancer risk was stronger for women than it was for men.
“The finding that women who smoke even a moderate number of cigarettes daily have an increased risk for colon cancer will account for a substantial number of new cases because colon cancer is such a common disease,” said Gram. “A causal relationship between smoking and colorectal cancer has recently been established by the International Agency for Research on Cancer of the World Health Organization, but unfortunately, this is not yet common knowledge, neither among health personnel nor the public.”
About the American Association for Cancer Research
Founded in 1907, the American Association for Cancer Research (AACR) is the world’s first and largest professional organization dedicated to advancing cancer research and its mission to prevent and cure cancer. AACR membership includes more than 34,000 laboratory, translational and clinical researchers; population scientists; other health care professionals; and cancer advocates residing in more than 90 countries. The AACR marshals the full spectrum of expertise of the cancer community to accelerate progress in the prevention, biology, diagnosis and treatment of cancer by annually convening more than 20 conferences and educational workshops, the largest of which is the AACR Annual Meeting with more than 18,000 attendees. In addition, the AACR publishes eight peer-reviewed scientific journals and a magazine for cancer survivors, patients and their caregivers. The AACR funds meritorious research directly as well as in cooperation with numerous cancer organizations. As the scientific partner of Stand Up To Cancer, the AACR provides expert peer review, grants administration and scientific oversight of team science and individual grants in cancer research that have the potential for near-term patient benefit. The AACR actively communicates with legislators and policymakers about the value of cancer research and related biomedical science in saving lives from cancer. For more information about the AACR, visit www.AACR.org.