(Reuters Health) – People who are exposed to secondhand smoke are more likely to develop oral cancer than their counterparts who do not have that exposure, a systematic review and meta-analysis suggests.
The researchers examined data from five previously published studies with a total of 1,179 cases of oral cancer and 5,798 controls. The analysis included 3,452 people who had exposure to second-hand smoke and 3,525 who did not.
Overall, people with second-hand smoke exposure were significantly more likely to develop oral cancer (probability 1.51), according to Tobacco Control researchers.
“It is estimated that tobacco smoke could have more than 4,000 chemicals, and about 70 of them have carcinogenic effects,” said the study’s lead author Luis Monteiro of the University’s Science Institute. Health of Gandra, Portugal.
“Therefore, it is logical that tobacco smoke that is released by the burning of tobacco products and by the exhaled smoke of smokers can also act as a carcinogen in non-smokers who inhale these gases,” Monteiro said for e-mail.
Prolonged exposure to second-hand smoke also appeared to increase the risk of oral cancer.
Compared with people without second-hand smoke exposure, people with exposure over 10 or 15 years had a more than doubled risk of oral cancer (OR 2.07).
With a second-hand smoke exposure of less than 10 or 15 years, the risk was lower, but still significantly higher than the lack of exposure (OR 1.56).
The researchers also examined how the intensity of second-hand smoke exposure influenced the risk of oral cancer. Compared with lack of exposure, the risk of oral cancer was lower for exposure less than 2 or 3 hours daily (OR 1.65) than for more than 2 or 3 hours daily (OR 2.15).
The researchers note that one of the limitations of the study is that they only identified a handful of studies to include in the meta-analysis. None of the included studies were of high quality and many had a potential for memory bias to influence outcomes, the authors also note.
The environmental factors underlying the causes of cancer are inextricably linked, and those factors were not part of the study’s analysis, said Elyse Park, a professor of psychiatry and medicine at Harvard Medical School and Massachusetts General Hospital. in Boston who did not participate in the study.
“Smokers are grouped into homes and communities, so cultural and community norms, exposure, and environmental risk are shared,” Park said in an email. “Smokers are also disproportionately more likely to have a low socioeconomic status; therefore, it is aligned that people who are exposed to second-hand smoke are also more likely to be so.”
Still, the results underscore that doctors should consider second-hand smoke exposure as a modifiable risk factor for cancer, said Dr. Michael Ong, a professor at the David Geffen School of Medicine and Fielding. School of Public Health, University of California at Los Angeles. .
“As doctors, we often neglect to ask patients about exposure to second-hand smoke,” Dr. Ong, who did not participate in the study, said by email. “However, exposure to second-hand smoke has significant health risks, both because of the risk of cancer as this study shows, and because of other health risks, such as cardiovascular disease.”
SOURCE: https://bit.ly/3nZ27Ve Tobacco Control, online April 26, 2021.