Lung cancer screening: who needs a low-dose CT and why an X-ray is not enough

Most people get their lungs checked once they already cough or feel short of breath. With lung cancer, that is often too late. By the time clear symptoms appear, the tumour is often past the first stage.

Screening exists to find the disease before it shows itself. Here we explain who should be screened, why doctors use a low-dose CT scan instead of a chest X-ray, and what happens if the scan finds something.

The UK's NHS warns that you may not notice any symptoms in the early stages of lung cancer. The tumour grows in tissue with no pain receptors, and the lungs have a large reserve, so breathing is not affected for a long time.

Early signs worth paying attention to

When signs do appear, they look like common illnesses. The NHS lists a cough that does not go away, shortness of breath, coughing up blood, chest or shoulder pain, frequent or lingering chest infections, weight loss without trying, loss of appetite and feeling tired all the time. That is why early symptoms are easy to blame on bronchitis or age.

If these complaints do not go away, see a doctor, even if you have never smoked. You can read more about the disease on our lung cancer page.

Are the signs different in smokers

For smokers, a cough and breathlessness often feel "normal" for years. So a change in the cough, new breathlessness or streaks of blood get noticed late. There are no special "smoker's" signs of a tumour. The symptoms are the same. They are just easier to miss.

The main cause is smoking. The longer you smoke and the more cigarettes a day, the higher the risk. The NHS also lists long-term exposure to secondhand smoke, COPD and other chronic lung conditions, a close relative with lung cancer, work with asbestos, air pollution and radon, a natural gas that can build up indoors.

Screening rules focus on smoking because it is easy to measure. Doctors count pack-years: packs per day multiplied by years of smoking. One pack a day for 20 years equals 20 pack-years. So do two packs a day for 10 years. Half a pack a day for 30 years gives 15 pack-years, which is below the usual screening threshold, but your doctor may still weigh it together with your other risks.

Screening means testing people without symptoms who have a higher than average risk. For lung cancer, the most widely used criteria come from the US Preventive Services Task Force (USPSTF). The US Centers for Disease Control and Prevention CDC recommends a yearly scan for people who meet all three conditions:

• are 50 to 80 years old
• have a smoking history of 20 pack-years or more
• smoke now or quit within the past 15 years

Ukraine does not have a national lung cancer screening protocol yet, so doctors follow international guidance and your personal risk. If you do not meet the criteria but have other risk factors, such as asbestos, family history or chronic lung disease, ask your doctor whether a scan makes sense for you.

Screening is not for people with symptoms. If you have a cough, blood in your phlegm or pain, that is no longer prevention. It is diagnosis, and your doctor will plan the tests.

Can an X-ray show lung cancer

It can, but often too late. On a plain X-ray, the lungs overlap with the heart, ribs and vessels, so a small tumour can hide. The same goes for fluorography, a simplified X-ray with even less detail used for mass checkups. It shows large tumours. Early ones it often misses.

A CT scan looks at the lungs in thin slices without overlap and can see nodules a few millimetres across. That is why it finds cancer at a stage when surgery can still cure it.

A large study called NLST proved the benefit. According to the US National Cancer Institute NCI, it included 53,454 heavy current or former smokers aged 55 to 74. In the group screened with low-dose CT, the risk of dying from lung cancer was 15 to 20 percent lower than in the group that had standard chest X-rays.

"Low-dose" means the scanner runs in a reduced-radiation mode. That is enough to find nodules in the lungs, which are mostly air. We cover CT radiation and safety in a separate article.

The scan takes a few minutes. You lie on the scanner table, hold your breath when asked, and the machine takes a series of slices. No contrast and no special preparation are needed. A radiologist reads the images and notes any nodules, their size and density.

Bring your referral if you have one and any earlier results: old CT scans, X-rays and reports. Comparing with them helps the radiologist tell an old scar from a new finding. Pregnant women have CT only when it is vital, so always mention a pregnancy in advance.

At Oberig Clinic, the scan is done in our Diagnostic Department and read by radiologists led by department head Taras Matsiievskyi. You can book a low-dose lung CT. If a suspicious nodule is found, we offer bronchoscopy with biopsy, CT-guided needle biopsy and a visit with an oncologist.

Most findings are small nodules that turn out to be benign. The CDC is honest about the risks of screening. A false positive is when the test suggests cancer that is not there. Overdiagnosis is when it finds a cancer that would never have caused harm. And repeated scans add up radiation.

So a finding is not treated right away. Your doctor checks the nodule's size and density, may order a follow-up scan later, and only orders a biopsy if there is real suspicion. Screening makes sense when you are ready to follow this path to the end, not stop at the first worrying report.

If your report does mention a nodule, keep calm and keep the disc with your images. Ask the radiology team for older scans if you had any. A follow-up scan that shows no change is reassuring, and often that is all you need.

One more thing. Screening does not replace quitting. The best way to lower your risk is to stop smoking. The scan helps you catch in time what has already happened.

How often should I be screened?

Under the USPSTF guidance cited by the CDC, once a year for as long as you meet the criteria. Your doctor sets the exact schedule, especially after a finding.

Is there a blood test instead?

No. There is no blood test that could replace the scan. The CDC names low-dose CT as the recommended screening test. Tumour markers are used to monitor diagnosed cancer, not to screen for it.

I quit smoking 20 years ago. Do I need a scan?

By USPSTF criteria, no, if more than 15 years have passed. But the risk does not disappear completely, so talk to your doctor if you have other risk factors.

Do people who never smoked need screening?

Routine screening is not recommended for them. A scan may be ordered for other reasons: long-term contact with asbestos or radon, lung cancer in close relatives, or symptoms.

Is a low-dose CT safe?

The radiation dose is low. But it adds up with repeat scans, so do not have them more often than your doctor advises.

Who can help me decide if I need screening?

A pulmonologist or a general physician. They will look at your smoking history and other risk factors and refer you for a scan if needed.

If you are over 50 and smoke or smoked for a long time, book a visit at Oberig Clinic. A pulmonologist will assess your risk, the Diagnostic Department team will do the low-dose scan, and an oncologist will plan next steps if needed. Our pulmonologists include Anton Sadomov, PhD, associate professor and physician of the highest category.

Book by phone at +38 044 521 30 03 or online.