By testing the oral tissue of smokers, the same information may be able to be revealed as an invasive lung tissue test. New research has shown that the cells in the mouth are closely connected to those in the lungs when looking for “cancer-inducing molecular alterations.”
The tissue lining the mouth and the lungs (this tissue is known as the epithelium) was analyzed in 125 chronic smokers. More specifically, “two crucial tumor-suppressing genes was analyzed. The genes, p16 and FHIT, are known to be damaged or silenced very early in the process of cancer development.”
Tests of the epithelium were performed on the 125 participants on two occasions, the second three months after the first. “The researchers tracked whether either p16, FHIT or both had been silenced by methylation – the attachment of a chemical methyl group to crucial spots in a gene that shut down its function. Patterns of methylation were compared between the tissues [in the lungs and mouth].”
The correlation between the mouth tissue and lung tissue was found by noting the percentages of p16 and FHIT that were silenced in the two regions. The correlation ended up being extremely substantial. “When methylation of either gene was considered positive, 37 of the 39 individuals (95 percent) with p16 and/or FHIT promoter methylation in the oral samples had promoter methylation in at least one matched bronchial sample.”
The 95 percent occurence of postive methylation in both the mouth and lungs is compelling evidence that their is a very strong connection between the two that would allow effective testing to be done in either of the two regions, with the mouth being a much less invasive and accessible region. “We are talking about just a brushing inside of the cheek to get the same information we would from lung brushings obtained through bronchoscopy,” says lead researcher and study author Manisha Bhutani.
Source: Defeat Diabetes Foundation: Bhutani, Manisha. Merville, Scott. 2008 American Association for Cancer Research Annual Meeting press release. April 2008.