Recent research conducted by the University of British Columbia (UBC)and BC Cancer denotes that precancerous lesions in the mouths of non-smokers are more likely to evolve into cancer than smokers.
Even though smoking unequivocally is related to mouth cancers, UBC dentistry PhD candidate Leigha Rock found that precancerous lesions in non-smokers are more than twice as likely to progress to cancer at an even faster rate than a smoking-associated counterpart. The study was published in Oral Oncology.
“This is the first published study where the main focus was to examine the difference in risk of progression to oral cancer between non-smokers and smokers with oral precancerous lesions,” says Rock, lead author of the study and a clinical research coordinator with BC Cancer. “While other studies have also reported a higher rate of transformation among non-smokers, we looked at multiple risk factors including genetic markers.”
Rock and colleagues looked at the case history of 445 patients with oral epithelial dysplasia (OED), a type of precancerous oral lesion, enrolled in the B.C. Oral Cancer Prediction Longitudinal study. One-third of the patients were non-smokers.
“As smoking rates decline, we are seeing an increase in the proportion of these types of lesions in non-smokers,” explains Rock.
Amongst the researchers’ findings were that lesions on the floor of the mouth in non-smokers were 38 times more likely to progress to cancer than in smokers. This study is the first to report on a quicker progression to cancer in non-smokers indicated at three-year and five-year rates of progression, and at 7 and 6.5 per cent higher than smokers, respectively.
The researchers suggest that the main difference in outcomes is due to a variance in the root causes of the lesions. In smokers, the OED is likely the result of environmental factors, whereas, in non-smokers, genetic susceptibility or mutations are likely to blame.
“Our findings show that molecular genomic markers can identify high-risk lesions, regardless of risky habits like smoking, and should be an important consideration in patient management,” says Rock.
The study’s results stress the importance of taking oral lesions seriously, especially when they occur in non-smokers: “If you see a lesion in a smoker, be worried. If you see a lesion in a non-smoker, be very worried. Don’t assume it can’t be cancer because they’re a non-smoker; our research indicates non-smokers may be at higher risk.”
This research was funded by the BC Cancer Foundation, the National Institutes of Health, and the National Institute of Dental and Craniofacial Research.