What is your risk of developing lung cancer?

Lung cancer is the deadliest cancer in Hong Kong, causing more than 4,000 deaths in 2019. While early detection allows early treatment, there are usually no symptoms in the early stages of lung cancer, and unfortunately diagnosis often occurs when the cancer is at a late stage. But this does not mean that there is no way to catch lung cancer in its early stages. International studies have shown that low-dose computed tomography (low-dose CT) can effectively identify early-stage lung cancer patients, in turn reducing overall lung cancer mortality.

While many people have heard of CT scans, low-dose CT may not be as well known. Low-dose CT is a non-invasive method of medical imaging emitting just one-tenth the dose of radiation of a traditional CT. Low-dose CT is able to capture multiple cross-sectional images of the body with greater clarity than normal X-ray scans, allowing even tiny lung nodules to be visualised.


A large-scale study in the United States has shown that in comparison to regular chest X-rays, lung cancer screening by low-dose CT may reduce lung cancer mortality by up to 20%. However, in recent years, the number of non-smokers diagnosed with lung cancer has been on the rise. Globally, around 15-20% of males and more than 50% of females with lung cancer are non-smokers. This raises the question: is there value in screening non-smokers?

To date, the medical community has not published guidelines for lung cancer screening in non-smokers, but certain Asian countries and regions such as South Korea, Japan, and Taiwan have already conducted a number of clinical studies in recent years. A Taiwanese study found that among more than 12,000 non-smokers who have at least one known risk factor for lung cancer, 313 were found to have lung cancer, with 96.5% being early-stage, showing that lung cancer screening is capable of diagnosing early-stage lung cancer among non-smokers.

Low-dose CT, though effective, is still not a perfect technique due to the possibility of false positives, which may result in patients being exposed to unnecessary and therefore potentially harmful treatment. The possibility of false negatives, on the other hand, may cause a necessary treatment to be delayed. Therefore, it is particularly important to first understand your risk of developing lung cancer before deciding to undergo screening.

Source text: Hong Kong Integrated Oncology Centre (HKIOC)

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Dr. Choy Tim Shing