The haze alarm is sounding again! Nowadays, there are endless news about haze and lung cancer, what with the incidence of lung cancer in Beijing rising 40% in 10 years, the incidence of lung cancer in women continuing to rise for 33 years, lung cancer leapfrogging breast cancer to become the number one most prevalent cancer in women, and the number of lung cancer patients in China accounting for more than 1/3 of the world ……
So has the relationship between lung cancer and haze been clarified? Can lung cancer be screened early like cervical cancer?
I. The relationship between haze and lung cancer is clearly revealed
Although there is a lack of large-scale investigation evidence on the relationship between haze and lung cancer. But let’s be patient and let me analyze one or two.
As we know, the size of suspended particles in the air ranges from 0.1-100 microns, of which 10 microns can enter the upper respiratory tract, 5 microns can enter the fine bronchi, and about 2 microns (PM2.5) can enter the alveoli, which is the deepest part of the lungs.
When PM2.5 enters the alveoli, it can directly damage the alveolar wall and lead to local inflammation.
When inflammation occurs, the body cells will start the differentiation and repair function. In the course of tens of billions of rigorous cell replication and differentiation, a small error can result in an “outlier” – which may be the cause of lung cancer. It has also been shown that inflammation and tumors are closely related, and tumors can be seen as unhealed inflammation from a certain perspective.
So extrapolating down, we can say: haze causes local inflammation in alveoli, which increases the risk of lung cancer!
Second, so scary, should I do a lung cancer screening?
Some people may ask, “If it is so terrible, should everyone be screened for lung cancer?” There is no need to be so hasty.
First of all, according to a survey, the detection rate of lung nodules is 24.2% even in the high-risk group, but it is confirmed that 96.4% of these nodules are not related to lung cancer (medically known as false positives). In the general population screening, the false-positive rate will be even higher.
Secondly, patients who are screened as suspected will need to be observed for 2 to 3 years before an answer is finally reached, which not only causes great panic to patients and families, but also is a waste of medical resources.
In addition, although the low-dose spiral CT used for screening is already relatively low in radiation, it does not mean that it is completely free of radiation. If you are not a high-risk group for lung cancer, it is not necessary for you to be exposed to this radiation for nothing.
3. Who needs to be screened? Let’s check the number
Then let’s talk about who belongs to the high-risk group of lung cancer and needs to be screened. At present, there is no large-scale research study in China, so the following is only my personal opinion on the current situation in China, combined with the content of the U.S. guidelines, to deduce the people who should be screened for lung cancer.
1.Compulsory Screening Population
Age 55-74
Smoking history >30 pack years (the number of packs per day and the number of years of smoking multiplied, such as: one pack a day for 30 years, or 2 packs a day for 15 years)
Quit smoking <15 years
2, high-risk groups: (recommended screening population)
Age > 40 years (including any of the following high-risk factors)
Smoking ≥ 20 packs a year
History of secondhand smoke exposure;
Family history of lung cancer;
History of other tumors;
Pulmonary fibrosis and chronic obstructive pulmonary disease;
Long-term outdoor sports in cities with severe haze;
Long-term exposure to oil fumes.
It is recommended that the above people should have low-dose spiral CT screening for lung cancer once a year.
Fourth, the best way to screen lung cancer, look here!
Next, let’s talk about what is low-dose spiral CT, which can effectively detect small lung nodules less than 1 cm and is more suitable for early screening of lung cancer. Some people may ask if it is okay to take X-ray? The answer is – no.
In a study, 53,454 residents aged 55-74 were screened with both low-dose spiral CT and X-rays, and the CT detection rate was 24.2%, meaning that nearly 1/4 of the so-called normal people were found to have nodules in their lungs, while the X-ray detection rate was only 7%.
Moreover, a comparison with CT showed that about 20% of the people with problems detected by X-ray were eventually confirmed to be unrelated to lung cancer.
The radiation dose of low-dose spiral CT is 1/4 of conventional CT. For people with high risk of lung cancer, the risk of lung cancer is much greater compared with the risk of this radiation.
V. Blood sampling for tumor markers, exploration in progress!
Many people have heard of tumor markers, this marker is the metabolites of tumors, they are released into the blood, and we can infer the presence of tumors through blood tests.
But unfortunately, no tumor marker of which type has been found to be effective for lung cancer screening.
VI. Genetic prediction of lung cancer, to be studied!
You may know a very hot news a few years ago that a foreign movie star had her breasts and ovaries removed prophylactically based on genetic prediction results. In the field of lung cancer, the academic community has not recognized the genetic prediction of cancer, and its feasibility and accuracy are yet to be studied.
In China, sputum testing for lung cancer-related genetic mutations is underway, and we hope to establish Chinese lung cancer high-risk population criteria based on big data as soon as possible.