Pineapple has always emphasized that in the face of any cancer, early detection, early treatment, and early cure are the best options. Therefore, prevention and screening are more important than treatment in terms of saving lives.
Lung cancer is no exception. the difference in survival rates between stage 1 and stage 4 lung cancer is huge, so screening is invaluable.
What kind of people should be screened for lung cancer?
At this time, only “high-risk group screening” is recommended. Who is a high-risk group? The definition is slightly different between the Chinese and US guidelines.
In China, the definition is:
- Age 50 to 75 years.
- Have at least one of the following risk factors:
- Smoking ≥20 packs/year (packs per day x years of smoking ≥20). For example, if you smoke two packs of cigarettes per day for more than 10 years, or one pack of cigarettes per day for more than 20 years, this is 20 packs/year. Note that this also includes former smokers who have smoked but quit for less than 15 years;
- Passive smokers;
- Occupational exposure to various carcinogens (e.g., asbestos, beryllium, uranium, radon, etc. exposure);
- History of malignancy or family history of lung cancer;
- History of chronic obstructive pulmonary disease (COPD) or diffuse pulmonary fibrosis.
(Image from Station Cool Helo)
The U.S. PreventiveServicesTaskForce definition is a bit simpler:
55 to 80 years old, smoking ≥30 packs/year. Again, this includes current smokers, or former smokers who have quit less than 15 years ago.
If this is not a high-risk group, such as a 30-year-old guy who does not smoke, screening is not currently recommended. The reasons for this are multiple, but there are two main ones:
First, the false-positive rate of screening can be particularly high in non-high-risk groups, and it is possible that 99% of people who screen for problems are actually fine, which can create unnecessary fear in the public.
Second, some screening tests can be minimally harmful, so it’s best not to use them if they’re not necessary.
How exactly do you screen for lung cancer?
There is really only one lung cancer screening method that has been shown to be effective and recommended by authorities, and that is low-dose spiral CT.
Previously, routine screening for lung cancer included X-ray chest radiography, sputum cytology, and serum tumor marker testing, but these screening methods were limited by sensitivity and specificity and were not ideal.Low-dose spiral CT, as the name implies, is a CT that exposes the examiner to less radiation.Screening with CT is sensitive, but conventional CT s radiation is high and expensive, and it is not well suited for mass screening of the general population. It wasn’t until the 20 century 90s when low-dose spiral CT (LDCT) was introduced that it really made a difference.
It is feasible because the lungs are structurally different from other tissues and organs in that they contain more air and are less dense, so a low dose of radiation can create a satisfactory image.
Low-dose CT reduces the radiation dose by 75% to 90% compared to conventional CT and the cost of the examination is lower. Also, low-dose CT overcomes the shortcomings of X light chest films that are insensitive to small non-calcified nodules and can detect microscopic disease < 5 mm in diameter, so it can detect more early resectable lung cancers in high-risk populations.
(Image from Station Cool Helo)
Experts recommend low-dose CT because there is objective evidence that such screening is effective.
Thus, low-dose CT truly enables early detection, early treatment, and early cure.In 2011, the National Lung Screening Trial, a randomized controlled study, showed that screening people at high risk for lung cancer with low-dose CT reduced lung cancer mortality by 20% compared with x-ray chest radiographs.
Another set of statistics is even more telling: studies have demonstrated that early-stage lung cancer accounts for 85% of cancers detected by low-dose CT, many of which are completely asymptomatic. At the same time, the overall 10-year survival rate for patients screened for lung cancer was as high as 80%; with timely surgery, the expected overall 10-year survival rate was as high as 92%.
There are also some high sounding screening tools on the market today, such as PET-CT, gene sequencing, and so on. Are they reliable?
The main value of these things is that they are used for cancer patients. They’re really good for diagnosing cancer, diagnosing genetic mutations, or monitoring the effectiveness of treatment, and so on. However, they need to be used with caution for general population screening. There are many reasons for this, including being too expensive, poor accuracy in detecting early stage cancer, and even potential harm to the body. For example, PET-CT, for example, has very significant radioactivity, much higher than low-dose CT.
For a variety of reasons, these tools are not cost-effective when used for screening and are not recommended.
I personally hope that in the future, there will be a good way to screen for lung cancer with sputum, saliva, or blood, which would be more convenient and safer. But there is not enough data to recommend it yet.
(Image from Station Cool Helo)
In conclusion,remember, the only recommendation from the authorities for lung cancer screening at this time is low-dose CT.
Final quick answers to a few questions of interest:
Is the radiation from low-dose CT safe?
Once a year is currently considered safe. The average radiation dose per low-dose CT is 0.61 to 1.50 mSv (millisieverts), and the American Association of Medical Physicists considers imaging to be safe as long as the single dose is under 50 mSv.
How often should I be screened?
For people at high risk of smoking, once a year is recommended.
Can non-high-risk people screen on their own if they want to?
While the guidelines only recommend screening for high-risk individuals, it is not recommended.
While the guidelines only recommend screening in high-risk groups, cancer screening is a personal issue. If non-high-risk people have to be screened, they can consider screening once every 2 to 3 years, because after all, low-dose CT still has radiation, and it costs money. Cancer screening is often about balancing risk and benefit; therefore, you need to make your own decisions.
What should I do if I screen for a lung nodule?
This is impossible to say in a sentence or two, so let’s show you the chart of solid nodule follow-up options given by the Chinese Medical Association.
In conclusion, the discovery of nodules definitely requires further observation or examinationPlease follow your doctor’s advice.