Snus Not Linked to Colorectal Cancer

Researchers from the Swedish Karolinska Institute have published a study in the International Journal of Cancer showing that snus use is not a risk factor for cancers of the colon, rectum and anus among Swedish men (abstract here).

Caroline Nordenvall, from the Department of Medical Epidemiology and Biostatistics, and colleagues studied over 300,000 male Swedish construction workers who enrolled in a health program from 1971 to 1992. The workers were followed for up to 37 years, and Nordenvall calculated the relative risks (RRs) for cancer of the colon, rectum and anus among smokers and snus users.

Compared with non-users of tobacco, smokers had RRs of 1.08 (95% Confidence Interval = 0.99 – 1.19) for colon cancer and 1.16 (CI = 1.04 – 1.30) for rectal cancer. These are very small increases, and only the latter is statistically significant. The RR for anal cancer among smokers was 2.41 (CI = 1.06 – 5.48). Although smoking has been implicated for many years as a risk factor for anal cancer, the sexually transmitted human papillomaviruses are known causes of this malignancy. Information on sexual behavior or venereal infections, not found in this study, might affect Nordenvall’s risk estimate for smoking.

Snus users did not have significantly elevated risks for any of these cancers. The RRs were 1.08 (CI = 0.91 – 1.29) for colon cancer, 1.05 (CI = 0.85 – 1.31) for rectal cancer and 0.61 (CI = 0.07 – 5.07) for anal cancer.

Nordenvall concluded her study with the following: “Our results from a large and homogenous cohort of Swedish male construction workers with up to 37 years of
follow-up do not convincingly support an important role of tobacco use in the etiology of colorectal cancer. As expected, an increased risk of anal cancer was associated with smoking.”