Lung cancer: Screening with low-Dose CT scans

Lung cancer is one of the most common and deadliest cancers. The symptoms tend to be non-specific, often causing its detection to be too late. Currently, there is no comprehensive screening. This could change with the use of low-dose CT scans. It should be noted that this is not just an issue of technical feasibility. A screening test must also make sense from a health policy perspective.

In this MEDICA-tradefair.com interview, Prof. Hans-Ulrich Kauczor explains what a screening program for the early detection of lung cancer using low-dose CT scans would ideally look like and lists arguments to support its implementation.

Prof. Kauczor, we are talking about early lung cancer detection by using a CT scan, and more specifically a low-dose CT scan. What is the difference between a conventional CT exam and a low-dose CT scan?

Prof. Hans-Ulrich Kauczor: They differ in terms of radiation exposure. A conventional CT scan exposes the patient to approximately five millisieverts. It is used to investigate suspected lung cancer and requires the administration of a contrast medium. A low-dose CT scan should deliver less than two millisieverts of radiation exposure and ought to be done without a contrast medium.

Does this require any device modifications?

Kauczor: No, it does not. Modern CT scanners can be adjusted to where we can successfully examine patients even at a reduced radiation exposure. The goal of the exam is to produce images that allow us to detect and analyze the distinctive solitary pulmonary nodules or coin lesions, despite the use of a low radiation dose. To this end, multiple algorithms have been developed in the past few years.

The idea of performing a screening for lung cancer with low-dose CT dates back to the U.S. National Lung Cancer Screening Trial or NLST. What were the findings of this study?

Kauczor: The NLST was a randomized control trial that screened smokers with a particular risk profile. One group of subjects received a low-dose CT scan, the other a standard chest x-ray. The study findings revealed that participants who received low-dose CT scans had a lower risk of dying from lung cancer than participants who received standard chest x-rays. Based on the NLST study, the U.S has implemented a screening for lung cancer with low-dose CT scans.

There is presently nothing comparable either here in Germany or at an international level. What would this type of screening look like?

Kauczor: As a general rule, I consider this type of screening test a sensible measure. However, to be successful from a health and socio-political perspective, we must also pay attention to various details or else there are many error sources that can do more harm than good, in addition to high costs.

This type of program must focus on individuals who have a high to a very high risk of developing lung cancer as a result of smoking, and it must also clearly define these persons based on applicable criteria. What's more, the program must also produce as few false-positive results as possible. This means we must also classify criteria for the CT scan results - for example, establish a size when a coin lesion is deemed positive for cancer. That would actually be the most difficult part: to specify the target differences of the procedure to where it misses as few cases of lung cancer as possible while still identifying as many benign changes correctly as possible right away, so that these cases do not become subject to further, invasive and diagnostic workups.

Incidentally, this was also one of the major critiques of the NLST implementation in the U.S. The study was designed to miss as few cases of lung cancer as possible but this led to many false-positive screening results. The vast majority of results subsequently turned out not to be lung cancer after all.

What efforts are made today to establish lung cancer screening programs?

Kauczor: There are no advanced efforts yet in both Germany and at the international level. Korea and Israel offer screening tests that participants have to pay for themselves. The same applies to some regions in Spain, Switzerland and Russia. Generally speaking, people are interested in lung cancer screening tests across the board. Yet to the best of my knowledge, outside of the U.S., there is still no real political decision to conduct a screening for lung cancer on a broader scale, and one that is comprehensively offered or covered by health insurance providers.

Do lung cancer screening programs actually make sense?

Kauczor: Absolutely! Needless to say, we would first have to try to stop people from smoking in the first place or to motivate them to quit once they have started. Smokers or people who have quit smoking should be offered a screening test for lung cancer. That being said, there is a partial lack of political will and resolve for a program that iws covered by health insurance companies. However, this is contradictory and inconsistent, since physicians treat people with lung cancer with all the remedies we have at our disposal - and at a much higher cost.

Lung cancer screening and the images we generate with it make it easier for us to make a case against smoking. They also tend to enable us to detect and treat cancer in time. There would also be an economic impact: a screening program that targets smokers between the ages of 50 and 65 would also include many people who are still working professionals. If we were to detect cancer or other changes associated with smoking at an earlier stage, we would be able to increase their life expectancy, improve their quality of life, and also allow them to extend their career longevity. In light of these facts, a preventive lung cancer screening would make a lot of sense in so many ways.