Screening smokers for lung cancer could save lives

BMJ Group News

What do we know already?

Each year nearly 38,000 people are diagnosed with lung cancer in the UK and more than 33,000 people die from it, making it the leading cause of death from cancer. Smoking is responsible for 9 in 10 of these deaths.

Although improved treatments are helping people live longer, the survival rate remains low, because most people are diagnosed when their cancer is advanced and difficult to treat.

This is why there's so much interest in screening for lung cancer. If doctors could detect the disease early among people at high risk, more people could have treatment to stop the cancer before it spreads, improving their odds of surviving the disease.

Several screening approaches have been studied, including chest x-rays. One of the most promising is CT scanning.

These scans produce detailed pictures of cross-sections of your body. Studies suggest that CT scans can detect more early-stage lung cancers than chest x-rays. But might this screening test actually save lives?

To find out, researchers recruited 53,454 current and former heavy smokers, who they screened for lung cancer once a year for three years. Half had CT scans and the other half had chest x-rays. They were then followed for an additional 3.5 years.

What does the new study say?

During the study, 1,060 lung cancers were diagnosed in the CT group, and 649 of these were detected by screening. By comparison, only 279 of the 941 cancers diagnosed in the chest x-ray group were detected by screening.

The cancers detected through CT scans were also more likely to be at an early stage than those detected through chest x-rays.

But, most strikingly, people in the CT group were 20 percent less likely to have died of lung cancer by the end of the study, compared with those in the chest x-ray group.

CT screening wasn't without drawbacks. Nearly 25 percent of people in the CT group had a positive screening test during the study, despite most not having cancer. This meant that they had to undergo further tests to find out that they did not have the disease.

By comparison, only around 7 percent of people in the chest x-ray group had a positive screening test during the study. Again, most of these turned out to be negative.

Complications from further tests were rare. And doctors were able to rule out cancer for many people by doing a follow-up CT scan. Even so, the stress of having a false-positive test result was likely to be a strain for many people.