New horizons for lung cancer?

Progress is being made in lung cancer

Beating lung cancer is one of our greatest challenges. It’s the most common cancer in the world – a staggering 1.61 million new cases are diagnosed every year. In the UK, it is the second most common cancer, and each year more than 38,000 people are diagnosed with the disease.

And improvements in survival rates for lung cancer have been modest – they haven’t yet mirrored the tremendous progress seen in some other diseases such as children’s cancers.

In fact, one in five people who die of cancer die from lung cancer. This is largely because it’s usually diagnosed at a late stage, when treatment is less likely to be successful.

Perhaps this is why we rarely see newspaper headlines screaming of breakthroughs in lung cancer. But actually there are good things to shout about when it comes to this disease.

In the UK, lung cancer treatment continues to improve across the NHS. And, as highlighted on this blog recently, there’s been a tripling of money spent on lung cancer research in the UK in just 8 years – proportionally more than in any other cancer.

Two pieces of research this month give us yet more hope that we’ll see better improvements in lung cancer survival rates in the future.

Progress towards effective lung screening

Last week ,US scientists published the largest and most rigorous trial of lung cancer screening to date – the US National Lung Screening Trial.

The results – showing a 20 per cent reduction in deaths from lung cancer in current or recent smokers who were offered annual CT scans as compared to chest x-rays – didn’t come as a surprise. They were first announced in 2010 when the trial was stopped due to the clear pattern of results emerging.

The study involved more than 50,000 current or former smokers aged between 55 and 74, who were randomly assigned to receive either an annual ‘low-dose spiral CT scan’ or chest x-rays over a three year period. Their health was then monitored for a further three years after screening stopped.

Over this time there were 356 deaths from lung cancer in the CT scan group and 443 in the chest x-ray group – which equated to a reduction in lung cancer death rate of 20 per cent.

Given the clear reduction in deaths from lung cancer in such a highly-regarded trial, the reaction from the scientific and public health communities could at first be considered somewhat understated. But there are a few crucial reasons why doctors are not yet calling for all smokers to opt for an annual CT scan of their chest.

1. The number of positive screening results was considerably higher in the CT scan group than the chest x-ray group (18,000 vs 5,000). The vast majority of these results turned out to be false positives – suspicious scans that turn out not to be cancer on further investigation (in fact, around 95% of positive results in both arms of the trial were false positives).
2. Although there were very few negative effects of the screening procedures themselves, there were risks associated with diagnostic tests following screening. Ten people from the CT scan group and 11 from the chest x-ray group died within 60 days of having investigative procedures following screening. A further 75 people in the CT scan group had a severe complication associated with diagnostic testing (24 in the chest x-ray group).
3. The trial compared two different modes of screening rather than comparing screening with no testing. So although there was no increase in overall death rate in the CT scan group compared to the chest x-ray group, both arms of the trial were associated with increased risks, and it is not clear how the risks and benefits of these screening procedures compare with no screening.
4. There was some suggestion that lung screening results in some degree of ‘overdiagnosis’ – that is, the diagnosis of some lung cancers that would never have progressed into more serious disease or caused any symptoms. The authors are calling for more research in this area, which is a sensible way forward.

Dr Harold Sox (past President of the American College of Physicians and chair of the U.S. Preventive Services Task Force) summed up the state of play eloquently in an opinion piece for the New England Journal of Medicine:

“The findings […] signal the beginning of the end of one era of research on lung cancer screening and the start of another. The focus will shift to informing the difficult patient-centred and policy decisions that are yet to come.”

The American Society of Clinical Oncology was also prompted to release a statement about these clinical trial results, praising the work as “an example of clinical research at its best”, but also echoing the sentiment of doctors from around the world:

“But we must remember that screening is not a substitute for quitting smoking. The overwhelming majority of lung cancer is caused by smoking, and smoking cessation will always have a far greater impact on lung cancer deaths than any screening tool. [Those] who wish to prevent deaths from cancer, respiratory illness or heart disease, the first step is to quit smoking.

Pain-killer emerges as promising candidate for lung cancer prevention

In yet more interesting but earlier-stage work, a different group of US scientists found evidence that a pain-killer often used by people with arthritis could one day help to prevent lung cancer in former smokers.

We need to be cautious about these results – the small clinical trial of a drug called celecoxib only measured a biological marker of cancer development called Ki-67, rather than looking directly at true cancer outcomes, such as numbers of people developing lung cancer. And the study looked at a relatively small number of people – 137 individuals. So it’s far too early to start recommending that former smokers start taking this drug to reduce their risk of lung cancer.

But the study is nevertheless encouraging and paves the way for a larger trial of the pain killer for lung cancer prevention. As our cancer prevention expert Professor Jack Cuzick told our news team:

“This is a small study that only looked at indirect measurements of lung cancer development, such as increased levels of a protein called Ki-67. So there’s a long way to go before recommending that former smokers take celecoxib. Scientists need to run much larger prevention trials that directly measure how the cancer develops if the drug is to reduce the number of people developing lung cancer.

“Nevertheless this is very interesting work which makes a strong case for doing these larger trials. In particular, this result shows that it might be possible to identify a group of patients for whom it is safe to take celecoxib. This is important because the drug is known to increase the risk of cardiac disease, so we’d only want to offer it when the benefits outweigh the risks.”

Steady progress

Our journey towards improved survival in lung cancer hasn’t been as quick as for some other cancers, but the above work highlights that there are glimmers of hope on the horizon – including the increase in funding we mentioned earlier. In fact, you can directly donate to one of our lung cancer research projects on our MyProjects website.

And it’s worth repeating that the first thing smokers can do to dramatically reduce their risk of lung cancer it to quit. After all, smoking causes 9 in 10 lung cancers. There’s more information about smoking – and quitting – on our main website.

Hazel Nunn

References:
The National Lung Screening Trial Research Team (2011). Reduced Lung-Cancer Mortality with Low-Dose Computed Tomographic Screening New England Journal of Medicine DOI: 10.1056/NEJMoa1102873

Mao, J. et al (2011). Lung Cancer Chemoprevention with Celecoxib in Former Smokers Cancer Prevention Research, 4 (7), 984-993 DOI: 10.1158/1940-6207.CAPR-11-0078