The smokeless tobacco product snus, which is used mainly in Sweden but also is sold in the U.S., may increase the risk that men with prostate cancer will die from their disease, according to a new study led by researchers at Harvard T.H. Chan School of Public Health.
The finding is built on previous studies that show increased risk of death from prostate cancer in smokers with the disease.
It suggests that nicotine or other non-combustion-related components of tobacco may play a role in prostate cancer progression.
The study is published in the International Journal of Cancer.
Snus is a powdered tobacco product, often sold in teabag-like sachets, that is placed under the upper lip for extended periods.
It contains nicotine but no combustion components, and has not been previously studied in relation to prostate cancer survival.
The researchers analyzed health data collected from Swedish construction workers during preventive health check-ups between 1971 and 1992, including a tobacco use questionnaire completed during each man’s initial check-up.
Of these men, 9,582 later developed prostate cancer. About half of the subjects died during the follow-up period–2,489 from prostate cancer.
Compared with those who never used tobacco, those who used snus but did not smoke had a 24% increased risk of dying from prostate cancer and a 19% increased risk of dying during the study period from any cause.
Among men whose cancer had not spread, increased risk of death from prostate cancer for exclusive snus users was three times higher than for never-users of tobacco.
Researchers suggest that although snus has been suggested as a less harmful alternative to smoking, men with prostate cancer who used snus are at higher risk of premature death.
This may be because snus contains nicotine. Evidence from animal studies has shown 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.
Taken together, this study suggests that the health effects of smokeless tobacco products should be carefully studied by public health officials.
Citation: Wilson KM, et al. (2016). Snus use, smoking and survival among prostate cancer patients. International Journal of Cancer, published online. DOI: 10.1002/ijc.30411.
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