Lung cancer screening: making visible what can still be treated in time

According to WHO (Globocan) data, more than 5,000 new cases of lung cancer are diagnosed in Portugal every year — and most are found late. It is nobody's carelessness: in its early stages, this cancer rarely gives signs. By the time symptoms appear, the disease is often at a stage where treatment options are more limited.

That is why waiting for symptoms is not a prevention strategy. For most people, the right answer is not smoking (or quitting) and keeping up routine care. For a specific higher-risk group, there is one more possible step: screening.

Screening is done with a low-dose computed tomography (CT) scan — a quick imaging exam, with no needles or contrast, using a radiation dose well below a conventional CT.

The large international trials (NLST in the United States and NELSON in Europe) showed that, in people at higher risk, this screening reduces lung cancer mortality by around 20 to 25% — because it finds tumours while they are still small, at a stage where curative treatment is more often possible.

Screening is not for everyone — it is aimed at those who stand to benefit most. The U.S. recommendation (USPSTF), the international reference in this area, points to people aged 50 to 80 with a smoking history of at least 20 “pack-years” (for example, one pack a day for 20 years, or two packs a day for 10), who currently smoke or quit in recent years. Time since quitting also weighs in the decision — and it is your doctor who assesses the whole picture.

Outside this group the balance changes: false positives and follow-up exams can outweigh the benefit. That is why it is a decision to make with your doctor, case by case. In Portugal, lung screening is not yet an organised population-based programme like breast or bowel screening — one more reason to bring it up at your appointment.

Few diseases carry as much stigma. The question “do you smoke?” often carries a judgement — and we know that judgement leads people to put off seeking care, contributing to later diagnoses. Medicine exists to understand, prevent and treat; not to judge.

And reality is more complex than the stigma suggests: around 15 to 20% of cases occur in people who never smoked, particularly women. Genetic predisposition, radon, air pollution and certain occupational exposures also count. If you smoke, quitting brings benefit at any age — and your doctor, or the SNS 24 line in Portugal, can help you on that path, without blame.

Before the appointment, three steps help — without alarm and without deciding alone: