Smoke and Mirrors
Posted by Exile on April 4, 2008
Here’s my own dig at junk science. I am a smoker. I smoke a pipe for pleasure and cigarettes at work because I can’t take an hour long smoke break. Which is my average time to smoke a pipe of my favourite baccy. I can understand my boss objecting. Four smoke breaks would be half the day’s work.
I found a report on the latest lung cancer gene studies. Yes. Lung cancer is gene related. Non-smokers get it too. It’s all in the DNA folks.
The report puts a question out first.
Smokers are much more likely to develop lung cancer than nonsmokers — that has been a scientific truism for decades. But what about the 85% of smokers who don’t develop lung cancer? Are they just the lucky ones?
Indeed. Are they just lucky? 15% of all smokers get lung cancer. Remember that. It’s important. Now read on.
A trio of new studies suggests that the explanation for why they escape the disease may lie partly in their genes.
Three new reports by research teams in the U.S., Europe and Iceland have identified, for the first time, specific gene variants that appear to make some smokers and former smokers more susceptible than others to cancer. The two variants — or differences in a single nucleotide — exist in about 34% of the population and occur in genes in the same region of the long arm of chromosome 15. Those genes code for nicotinic acetylcholine receptors, cell-surface proteins that selectively bind to nicotine molecules. Once nicotine attaches to these receptors, a series of changes in the cells is triggered: in the lungs, for example, cells are pushed into rapid, uncontrolled growth, which promotes the growth of new feeder blood vessels, creating, in turn, a particularly hospitable environment for cancer tumors. The new studies, published in Nature and Nature Genetics, found that smokers who possessed one copy of either variant were 28% more likely to develop lung cancer, while those with two copies were at a stunning 81% increased risk for the disease.
The other two studies examined the cancer risk and smoking habits of current and former smokers, with and without cancer, with a carefully matched control group of never-smokers. While the variants were associated with an increased risk of lung cancer in smokers, that genetic predisposition is not destiny. In the U.S.-based study, led by Christopher Amos, an epidemiologist at the M.D. Anderson Cancer Center in Houston, people who never smoked but still had the genetic variants showed no increased risk of lung cancer, which suggests that nicotine might be necessary to trigger the tumor-building process — and that smokers with this particular genetic profile are only at greater risk for developing lung cancer if they expose their airways to nicotine.
Now that’s interesting. “People who never smoked but still had the genetic variants showed no increased risk of lung cancer.” No increase compared to which base line data? Because there is a risk for non smokers of developing lung cancer.
Amos’s study included only a small number of nonsmokers, however; the European study, which included a larger sample, did find a slightly higher risk of lung cancer in nonsmokers with the genetic variants. That could explain some of the genetic risk that leads to lung cancer in the 10% of men and 20% of women who develop the disease every year despite never having lit up.
Hmmm.. even more interesting. Remember that 15% figure I told you keep in mind?
Using the figures found in the study, take 50 men and 50 women, all non-smokers. 10% of 50 men is 5 men. 20% of 50 women is 10 women. Add those together and what do you get?
50 + 50 = 100.
5 + 10 = 15.
Ergo: 15% of all non smokers get lung cancer.
Strange. Only 15% of all smokers do too.