Decreased levels of vitamin D may further raise a smokers risk of developing tobacco-related cancer, according to a study.
The study illustrates that simple vitamin D blood tests and supplements have the potential to improve smokers health, researchers reported in an article published March 15 on the website of Clinical Chemistry, the journal of the American Association for Clinical Chemistry.
In the U.S., cigarette smoking is the primary causal factor for at least 30% of all cancer deaths, and can lead to multiple kinds of cancer, including bladder, cervical, esophageal, head and neck, kidney, liver, lung, pancreatic, stomach and myeloid leukemia, according to background information in the study. According to the Centers for Disease Control and Prevention, the healthcare expenditures and productivity losses due to smoking cost the economy approximately $193 billion per year.
In this paper, Danish researchers measured plasma vitamin D levels in blood samples collected in 1981-83 from 10,000 residents of Denmark. The researchers then followed the study participants for up to 28 years through the Danish Cancer Registry. Of the participants, 1,081 eventually developed a tobacco-related cancer.
The researchers determined that the median vitamin D concentration among these participants was only 14.8 ng/mL, versus the higher 16.4 ng/mL median concentration found for all participants together.
“Decreasing 25(OH)D concentrations, subdivided by clinical categories or by seasonally adjusted percentile categories, were associated with increasing cumulative incidence of tobacco-related cancer,” the researchers wrote. People with a concentration of less than 5 ng/mL had a 75% higher risk of tobacco-related cancer than those whose concentration was 20 ng/mL or higher. Those whose vitamin D concentration was in the 5th percentile or lower had more than twice the risk compared with those who were in the 66th percentile or higher.
The researchers said these results show for the first time that the risk of tobacco-related cancers as a group is associated with lower concentrations of vitamin D. The data also indicate that tobacco smoke chemicals may influence vitamin D metabolism and function, while vitamin D may conversely modify the carcinogenicity of tobacco smoke chemicals.
If further research confirms the findings, it would be consistent with previous studies demonstrating the anti-tumorigenic effects of vitamin D derivatives and correlation of vitamin D deficiency with favorable cancer-forming conditions and increased susceptibility to tobacco smoke carcinogens. However, there was no connection between low vitamin D levels and risk of cancer that was not tobacco-related, the researchers noted.
“Our analyses show that the association between lower concentrations of plasma vitamin D and higher risk of cancer may be driven by tobacco-related cancer as a group, which has not been shown before,” study author Børge G. Nordestgaard said, according to a news release. “This is important for future studies investigating the association between plasma vitamin D and risk of cancer.”
The study abstract is available at www.clinchem.org/content/early/2013/01/17/clinchem.2012.201939.abstract.