Researchers Confirm That Genes Increase Risk Of Lung Cancer In Smokers

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Main Category: Lung Cancer
Also Included In: Smoking / Quit Smoking;  Genetics
Article Date: 21 Aug 2009 - 2:00 PDT

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UK researchers who searched the DNA of over 5,000 smokers and non-smokers have found more evidence that inherited genes can increase a smoker's risk of developing lung cancer and also decide the type of cancer that develops.

The study was the work of researchers from the Institute of Cancer Research and is published in the 15 August issue of Cancer Research. The lead author was Professor Richard Houlston, a Cancer Research UK funded scientist at The Institute of Cancer Research.

Houlston and colleagues conducted the genome-wide association (GWA) study in two phases.

First they scanned the genomes of 1,900 people with lung cancer and compared them to those of 1,400 people without lung cancer to find differences in DNA that were linked to an increased risk of the disease.

Then they looked for these same changes in the genomes of another 2,000 people with lung cancer and compared them to the genomes of around the same number of people without lung cancer.

They found differences in three regions of the genome, at chromosomes 5, 6, and 15, that appeared to be more common in the people with lung cancer than the people who did not have it. Some of these links were already known about before.

Houlston said in a press statement that:

"This research confirms work done at the ICR and elsewhere that has previously implicated these areas in lung cancer risk and the type that develops."

But in this study, Houlston and colleagues discovered more detail. For instance, they found that the link between chromosome 15 and lung cancer is more complex than originally thought.

Confirming that there are two sites in this location that influence lung cancer risk, they also calculated that people with one copy of each variant who smoke or used to smoke have a 28 per cent increased risk of developing lung cancer, whereas current or former smokers who carry both copies of each variant have an 80 per cent higher risk.

People who do not smoke can also carry these changes, but the risk is only higher for those who smoke.

These genetic variants are in a family of genes that are known to influence smoking behaviour and consumption of tobacco. They also play a role in cell growth and death.

Houlston and colleagues also found that the variant at chromosome 5 influenced what type of lung cancer developed. People with the variant are more likely to develop a type of non-small cell lung cancer (NSCLC) known as adenocarcinoma, which accounts for 27 per cent of lung cancer cases in the UK. It is also the most common lung cancer in non-smokers.

The variant that they found on chromosome 6 appears to influence whether the type of NSCLC that develops is either adenocarcinoma or squamous cell carcinoma.

Houlston said the next step is to:

"Dig deeper to pin point which gene, or genes in these regions, cause the increased risk of developing lung cancer and how they actually trigger this increase."

Dr Lesley Walker, director of cancer information at Cancer Research UK, said:

"Smoking greatly increases the risk of lung cancer -- causing nine out of ten cases of the disease. This research shows that inherited genetic variation accounts for some of this risk and the type of lung cancer that develops."

"It's important to remember that smoking also increases the risk of other life-threatening diseases including heart disease, stroke and a dozen other cancers. The best thing a smoker can do to reduce their risk of lung cancer, and a range of other life-threatening conditions, is to quit," she added.

"Deciphering the Impact of Common Genetic Variation on Lung Cancer Risk: A Genome-Wide Association Study."
Broderick, Peter, Wang, Yufei, Vijayakrishnan, Jayaram, Matakidou, Athena, Spitz, Margaret R., Eisen, Timothy, Amos, Christopher I., Houlston, Richard S.
Cancer Research 69, 6633, August 15, 2009.
DOI: 10.1158/0008-5472.CAN-09-0680

Source: ICR.

Written by: Catharine Paddock, PhD
Copyright: Medical News Today
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