What are the diagnostic methods for lung cancer

In recent years, the incidence of cancer has been rising in my country. Many people do not realize that lung cancer has become the number one killer of cancer. Therefore, differential diagnosis of lung cancer, especially early cases, is of great significance for early diagnosis and early treatment. Let's take a look at the diagnosis methods of lung cancer:

1. Cytology: Most patients with primary lung cancer can find detached cancer cells in their sputum, and the histological type of cancer cells can be determined. Therefore, sputum cytology is a simple and effective method for lung cancer screening and diagnosis. After getting up, rinse your mouth with clean water. Fresh sputum coughed up from the deep lungs or endobronchial secretions sucked out by bronchoscope can be used as examination specimens. Multiple sputum cytology examinations can increase the positive rate. The positive rate of sputum cytology examinations for central lung cancer can reach 70-90%, while the positive rate of sputum examinations for peripheral lung cancer is only about 50%. Therefore, those with negative sputum cytology examinations cannot rule out the possibility of lung cancer. Squamous cell carcinomas are mostly located in larger bronchi, and the tumors grow into the lumen. The surface cancer cells are easy to fall off, so the positive rate of sputum examinations is high, and the determination of histological types is also more accurate. The positive rate of sputum examinations for undifferentiated small cell carcinomas is also high, but it is not easy to determine the histological type.

In cases where lung cancer metastasizes to the pleural or pericardial cavity, causing pleural or pericardial effusion, part of the effusion is extracted, centrifuged and the precipitate is taken for smear examination. If cancer cells are found, a definitive diagnosis can be made.

2. Mediastinoscopy: It is mainly used to determine the extent of central lung cancer invading the mediastinum. Through a short transverse incision at the upper edge of the sternal notch, the neck strap muscles and the pretracheal fascia are cut longitudinally along the midline. The pretracheal fascia is separated by blunt method behind the innominate artery and the aortic arch with fingers to reach the tracheal carina area, and then the mediastinoscope is inserted to observe the enlarged lymph nodes. Lymph nodes are aspirated or removed by puncture for pathological section examination. Patients with positive mediastinal lymph nodes, especially those with metastasis or undifferentiated lung cancer in the contralateral mediastinal lymph nodes, are contraindications for lung resection.

3. Percutaneous puncture lung biopsy: For masses or invasive lesions near the chest wall suspected of peripheral lung cancer or diffuse alveolar bronchiolar carcinoma, if other diagnostic methods are used but the nature of the lesion cannot be determined, and the patient's physical condition is not suitable for thoracotomy, percutaneous puncture lung tissue biopsy can be used. Determine the location of the lesion under X-ray television fluoroscopy, and insert the puncture needle into the central part of the lesion while asking the patient to hold his breath under local infiltration anesthesia, pull out the needle core, connect a 30-50ml syringe, rotate the puncture needle while applying negative pressure suction, and then quickly pull out the puncture needle, and send the collected specimen for pathological examination. After percutaneous lung puncture, close attention should be paid to the presence of pneumothorax, hemothorax and hemoptysis. The positive rate of peripheral lung cancer cases can reach 80%, and the incidence of complications is not high. Lesions that have metastasized to the pleura can also be examined by taking pleural tissue through skin puncture for pathological examination.

4. Radionuclide examination: Radioactive drugs such as 67Ga-citrate have an affinity for lung cancer and its metastatic lesions. After intravenous injection, they can be concentrated in the tumor and can be used to locate lung cancer and show the scope of the cancer. The positive rate can reach about 90%. However, other non-cancerous lesions such as lung inflammation and tuberculosis can also show concentration. Therefore, a comprehensive analysis must be conducted in combination with clinical manifestations and other examination data.

Lung perfusion and ventilation scanning using 133Xe can determine the impact of lung cancer lesions on bilateral lung function, thereby helping to determine the indications for surgical treatment.

5. Biopsy of metastatic lesions: For patients with advanced lung cancer who have metastases to the superficial lymph nodes above the clavicle, neck, axilla, etc., or subcutaneous metastatic nodules, the metastatic lesion tissue can be removed for pathological section examination or puncture and extract tissue for smear examination to confirm the diagnosis.

6. Mediastinotomy: It is difficult to observe the lesions of the left anterior mediastinum below the level of the aortic arch through mediastinoscopy. In order to avoid the adverse consequences of unnecessary thoracotomy in a few cases of central lung cancer, a mediastinotomy with less trauma to the body can be considered. Through the second intercostal incision of the left anterior sternum, or the removal of a short section of the second or/and third costal cartilage under the tunic, ligation of the internal thoracic blood vessels, and pushing the pleura outward, the mediastinum and hilar lymph nodes can be exposed, making it easier to obtain tissue for pathological examination. Although this examination method has not been widely used, it has certain reference value for some cases when formulating treatment plans.

7. Thoracotomy: If the nature of the lung mass cannot be determined after multiple examinations and short-term exploratory treatments, and the possibility of lung cancer cannot be ruled out, thoracotomy should be performed if the patient's general condition permits. During the operation, appropriate treatment will be given according to the condition of the lesion and the results of pathological tissue examination. This can avoid delaying the disease and causing lung cancer cases to lose the opportunity for early treatment.

8. Sputum cytology: Sputum cytology (sputum test) has been widely used in the diagnosis of lung cancer. Sputum test does not require expensive equipment, is simple and easy to perform, is painless to the patient, and has a wide range of applications. Sputum test can also be used to screen people at high risk of lung cancer.

9. X-ray examination: Chest X-ray is the most important examination in the diagnosis of lung cancer.

10. CT examination: CT examination is superior to conventional X-ray examination to a great extent.

11. Magnetic resonance imaging (MRI) : The contrast and resolution of MRI are better than those of CT, making it easier to identify and clarify the relationship between substantial tumors and blood vessels.

12. Magnetic resonance spectroscopy (MRS) examination: This is an older technology that is now also used as a means to distinguish whether the disease is benign or malignant.

13. Bronchoscopy: Bronchoscopy is an effective means of diagnosing lung cancer. It can observe the location and range of the tumor, obtain tissue for pathological examination, and infer the possibility of surgical resection based on the condition of the vocal cords, trachea and carina.

The above are the main diagnostic methods for lung cancer. We hope that it will be helpful to you. We will feel very honored. Expert Tips: If you have symptoms of disease, do not delay diagnosis. You should go to a regular hospital for treatment in time to avoid delaying the disease and causing serious consequences. If you have other questions, please consult our online experts.

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