The incidence and death rate of lung cancer worldwide are increasing year by year, and the treatment of lung cancer has become a major focus of attention, while diagnostic research, which is the basis of treatment, is extremely critical, and early diagnosis has become a top priority.
I. Incidence of lung cancer
1.Incidence of lung cancer in the United States
In the United States, the mortality rate of lung cancer from 1930 to 1990 was on the rise among both men and women, and both became the first place.
2.Epidemiological review of lung cancer in China
Comparing the number of lung cancer patients in China in 2000 and 2005, we found that the number of both male and female patients increased significantly between the five years, with a growth rate of 26.9% for men and 38% for women, and a total increase of 30% for both sexes.
II. Diagnosis of lung cancer
1.Main diagnostic methods
(1) Imaging diagnosis: chest X-ray, chest CT, MRI
Chest X-ray is the most commonly used, but its disadvantages are: when the lesion is small, chest X-ray cannot show it; overlapping tissues will also cause leakage. Chest CT has higher resolution and can also overcome the shortcomings of chest X-ray, so it is of high value in the early treatment of lung cancer. On the other hand, MRI does not have more advantages than chest CT in early diagnosis of lung cancer, and it shows the enlarged lymph nodes and vascular changes in mediastinum and hilar lymph nodes more clearly, but patients with enlarged lymph nodes in hilar lymph nodes are not early stage anymore. In a comprehensive comparison, chest CT plays a key role in the early diagnosis of lung cancer.
(2) Cytological histological diagnosis
Sputum exfoliated cells, pleural fluid exfoliated cells
Fibrinoscopy: biopsy (TBB, TBLB), brush examination, lavage, TBNA
Percutaneous lesion puncture
Mediastinoscopy, thoracoscopy, open-heart lung biopsy
(3) Serum cancer markers
Abnormal proteins including CEA, NSE, SCC, etc. can indicate cancerous lesions, but the sensitivity of these diagnostic indicators is relatively low.
(4) Newer diagnostic methods: including FDG-PET, fluorescence fibrinoscopy, genetic diagnosis, etc.
2.How to make early diagnosis?
How to use the above methods for early diagnosis? Can we use census means? That is, through two methods, chest X-ray and sputum exfoliated cells, during the routine physical examination of normal people.
3.High-risk group of lung cancer
The high-risk group of lung cancer refers to male smokers over 40 years old (smoking up to 400 cigarettes/year), as well as other passive smokers and people in special occupations, such as those exposed to radioactive gases and asbestos and tin mines. Screening in high-risk groups is more likely to detect lung cancer patients.
4.Sputum cytology examination
The specificity of sputum cytology examination is as high as 98%, that is, if cancerous cells are found in the patient’s sputum, then there is 98% possibility of confirming the diagnosis of lung cancer.
If cancerous cells are found in the sputum of a patient, there is a 98% chance that the diagnosis of lung cancer can be confirmed, which means that its reliability is 98%. However, the sensitivity is low (65%), which means that a significant proportion of patients will be missed. The healthy population can be screened with sputum exfoliation cell examination and chest X-ray.
5.Negative results, what should I do?
There have been 3 large scale screenings in the world, but unfortunately the results were negative. Such a kind of intervention which invested a lot of human and material resources does not produce good benefits for the diagnosis and treatment of lung cancer, and only individual patients benefit. So how should the clinic treat it properly. The clinical focus is on the diagnosis and treatment of patients who visit the clinic for the disease.
III. Main clinical manifestations
Here is a brief description of clinical manifestations. The clinical manifestations of lung cancer are less characteristic, but can be diagnosed and treated by combining various features, mainly as follows.
Cough.
Hemoptysis.
Wheezing.
Chest pain.
Obstructive pneumonia.
Weight loss.
IV. CT and PET
Since screening by a combination of sputum exfoliated cells and chest radiographs is not very useful, is it possible to try the CT approach? Because some small lesions (4-5 mm) can be detected by CT. This is a promising diagnostic method.
1.Low-dose spiral CT
Fast scanning speed, high resolution easy to find small lesions. For the healthy group for census, reduce the dose of radiation is beneficial to the human body, and is clinically feasible, and a large number of clinical trials have been made internationally.
2.Application of CT screening
Patients with lung cancer can be detected through low-dose spiral CT screening, and then further diagnosed and identified through high-resolution CT. The detection rate of lesions using CT has risen from less than 50% in the past to more than 80% now.
With the development of technology, the role of PET in the diagnosis of lung cancer has been more recognized.PET, or Positron Emission Scanning, can be used to identify cancer cells because of the vigorous metabolism of tumor cells and anaerobic enzymes.PET can detect lesions smaller than 6-7 mm, but the accuracy decreases. PET has been reported to have a sensitivity of 96% and specificity of 84% for the identification of some isolated nodules, which are already quite high in post-imaging diagnostics
PET also has some limitations in lung cancer diagnosis. For example, tumors with low metabolism such as bronchoalveolar cell carcinoma and carcinoid tumors (with an accuracy of about 50%) have resulted in false-negative diagnoses. And inflammatory lesions, especially active granulomatous inflammation. Active tuberculosis, active histoplasmosis, and active other granulomas can result in false-positive diagnoses.
In the rapid development of new bronchoscopes, fluorescent fibrinoscopy is increasingly used, and several companies around the world have developed corresponding products. The principle of action: the reflection of light changes when the number of cell layers increases, and the color of fluorescence is no longer green as normal, but red. This improves the accuracy of the test.
Also confocal microfibrilloscopy is developing faster.
In summary, how can early diagnosis be achieved? As mentioned earlier the utility of screening by combination of sputum exfoliation cells and chest radiographs is small, CT, especially low dose CT combined with sputum exfoliation cells has some value, but its prospective results are still not final. For clinical purposes, our focus should still be on symptomatic treatment. In fact, the development of early diagnosis of lung cancer is not ideal at this stage, and its development still needs our clinicians to summarize experience and propose innovative ideas in the process of practice. The task of improving the early diagnosis of lung cancer is a long way to go.