Thursday, April 03, 2008

Cancer Risk and Genes

The latest issue of Nature has this important study on the discovery of a genetic link for lung cancer.

The study is titled "A variant associated with nicotine dependence, lung cancer and peripheral arterial disease" by Thorgeir E. Thorgeirsson et. al. Here is the abstract:

Smoking is a leading cause of preventable death, causing about 5 million premature deaths worldwide each year. Evidence for genetic influence on smoking behaviour and nicotine dependence (ND) has prompted a search for susceptibility genes. Furthermore, assessing the impact of sequence variants on smoking-related diseases is important to public health. Smoking is the major risk factor for lung cancer (LC) and is one of the main risk factors for peripheral arterial disease (PAD). Here we identify a common variant in the nicotinic acetylcholine receptor gene cluster on chromosome 15q24 with an effect on smoking quantity, ND and the risk of two smoking-related diseases in populations of European descent. The variant has an effect on the number of cigarettes smoked per day in our sample of smokers. The same variant was associated with ND in a previous genome-wide association study that used low-quantity smokers as controls, and with a similar approach we observe a highly significant association with ND. A comparison of cases of LC and PAD with population controls each showed that the variant confers risk of LC and PAD. The findings provide a case study of a gene–environment interaction20, highlighting the role of nicotine addiction in the pathology of other serious diseases.

And here are a few samples from the NatureNews report about the study.

Three independent genetic studies have found some of the strongest evidence yet that your genes influence your risk of developing lung cancer.

....About 50% of the general population carries a single copy of this cancer gene variant, members of the three research groups suggest. Data from all three studies — some of which did not include non-smokers — show that possessing this single copy raises the risk of lung cancer by about 30%.

What's more, another 10% of the population is likely to carry two copies of this set of mutations, raising cancer risk by as much as 80% relative to people with equivalent lifestyles without the cancer-linked gene variant.

A typical smoker who refuses or fails to give up has a roughly 15% risk of lung cancer over their lifetime. But with two copies of the genetic variant, this rises to 23%. In contrast, someone who has smoked fewer than 100 cigarettes in their entire life has a less-than-1% chance of developing the disease.

These stats provide yet more reasons for taking seriously the most fundamental moral requirement you owe yourself- looking after your health. Help reduce the 5 million annual death toll caused by smoking, quit today!