The pope has a lung nodule. What does this mean? And what’s the risk of cancer?

Pope Leo will undergo surgery in the coming days to remove a lung nodule that was detected during a routine check up.

The 71-year-old said the growth was “well contained” and spotted early.

So what exactly is a lung nodule, and what’s the link with cancer? Most are spotted incidentally Lung nodules are small growths found in the spongy tissue of the lungs.

They are no more than 3 centimetres in diameter, and can be round or irregularly shaped.

Anything larger is referred to as a mass.

Lung nodules are usually detected by imaging of the chest, often using an X-ray or a computed tomography (CT) scan.

While some people undergo screening specifically for lung nodules due to their increased risk of cancer, many nodules are picked up incidentally from unrelated scans .

How common are lung nodules? Lung nodules are very common.

In a study of 10,431 non-smoking (never or former smoking) participants given a chest CT scan in the northern Netherlands, 37.7% of women and 47.5% of men had at least one lung nodule.

In the United States, lung nodules are detected in 31% of chest CT scans .

The Australian National Lung Screening program suggests that lung nodules will be found in up to half of all people screened , but that most are neither symptomatic nor cancer-related.

As imaging technology improves, and scans are performed more often, more lung nodules are likely to be detected.

Read more: Australia’s lung cancer screening program is a year old.

But can the health system deliver? What causes lung nodules? Older people, those who smoke, people with a family history of lung cancer and those exposed to asbestos are more likely to have lung nodules .