Snus, a smokeless and moist powder tobacco product that is particularly popular in Sweden but also sold in the United States, increases prostate cancer patients’ chances of dying from their disease, and of dying prematurely from any cause, new research reports.
The study, “Snus use, smoking and survival among prostate cancer patients,” published in the International Journal of Cancer, suggests that its tobacco-related components, especially nicotine, may promote cancer progression independent of tobacco’s known dangers when smoked.
“Snus has been suggested as a less harmful alternative to smoking because it lacks the combustion products of smoking that are associated with cancer risk. However, we found that men with prostate cancer who used snus were at increased risk of premature death,” Kathryn Wilson, a study co-first author and research scientist in the Department of Epidemiology at Harvard Chan School, said in a press release.
Snus, often sold in teabag-like sachets, is a powdered tobacco product that is placed under the upper lip for extended periods to allow nicotine to be absorbed.
In addition to cigarettes, the potential effects of snus on cancer progression is of interest to health officials, with the study reporting that authorities like the World Health Organization generally suggest snus as a risk-reducing alternative to smoking. Tobacco companies, including those in the U.S. since 2006, also have been introducing and promoting its use as a healthier alternative.
To assess the effects of snus in prostate cancer survivors, Wilson, Sarah Markt, and colleagues at the Harvard T.H. Chan School of Public Health, examined data from a cohort of 336,381 male Swedish construction workers who received preventive health check-ups between 1971 and 1992. Of these, 9,582 men developed prostate cancer.
Prostate cancer patients were divided into four categories: those who never used any tobacco products, those who used only snus, patients who were smokers (cigarette, cigar, or pipe), and patients who used snus and smoked.
During 36 years of follow-up, 4,758 patients died, 2,489 due to prostate cancer. Compared to patients who never used tobacco products, exclusive smokers had a 15 percent increased risk of dying from prostate cancer, and a 17 percent increased risk of dying from all causes. This was consistent with previous studies showing that smoking affects the survival of cancer patients.
Interestingly, so did snus. Exclusive snus users had a 24 percent and 19 percent increased risk of dying from prostate cancer or all causes, respectively. This risk was even higher in men diagnosed with nonmetastatic disease, who had a 3.2-fold higher risk of dying from prostate cancer compared to non-users.
“There is some evidence from animal studies that nicotine can promote cancer progression, and snus users have high blood levels of nicotine. Snus users are also exposed to other carcinogens in tobacco even though it is a smokeless product,” said Markt, a research associate in the Department of Epidemiology. “Taken together, this suggests that the health effects of smokeless tobacco products should be carefully studied by public health officials.”