Scientists have discovered a gene which appears to protect against lung cancer.
90% of lung cancer cases are linked to smoking
The University College London team says faulty versions of the gene are strongly associated with the development of tumours.
The study, published in Proceedings of the National Academy of Sciences, found mutations in the LIMD1 gene were common in lung cancer samples.
The authors say their work could lead to new avenues of research, and even treatments, for the disease.
Lung cancer is the biggest cause of cancer death in the UK, claiming around 33,600 lives a year, and it is notoriously difficult to treat.
Around 90% of cases are caused by tobacco use.
However, scientists have understood relatively little about the molecular basis of lung cancer.
The LIMD1 gene studied in this research is located on part of chromosome 3 called 3p21.
Scientists have long suspected that 3p21 is home to important tumour suppressor genes, as it is missing in many types of cancers.
Tumour suppressor genes stop tumours developing. Mutations in these genes stop them doing their job properly and so help cancer develop.
Chromosome region 3p21 is known to be missing in more than 90% of lung tumours.
The team say their discovery that LIMD1 activity is reduced in most of the samples they tested is added evidence that LIMD1 mutations are important in lung cancer development.
Tests on mouse lung cancer cells showed restoring LIMD1 function to lung cancer cells in mice significantly delayed tumour growth.
Dr Tyson Sharp, who led the research team at the Wolfson Institute, says: "We have found a new tumour suppressor gene.
"Our experiments suggest its loss may be an integral part of the development of lung cancer.
"Chromosome 3p is often deleted early in the development of lung cancer, which implies that inactivation of the LIMD1 gene could be a particularly important event in the early stages of lung cancer."
He added: "Identifying mutations in key genes such as LIMD1 could enable earlier diagnosis of cancer, as they are early warning signs that something is going wrong."
The team now plan to examine if carcinogens in tobacco cause damage to chromosome 3p and therefore faults in the way the LIMD1 behaves.
The research was funded by Cancer Research UK, with additional funding from the Wellcome Trust.
Professor Robert Souhami, Cancer Research UK's Director of Policy and Communication, says: "Identifying the most important genetic mutations in each type of cancer is an important area of research.
"Scientists hope to design drugs to replace the function of mutated tumour suppressor genes.
"The team's findings offer a new target in the search for treatments for lung cancer."