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Ung thư và Phòng ngừa : Glossary
Lung Cancer
[2007-09-21 10:29] (1,830)



Compared to other types of cancers, the prognosis of lung cancer is worse. Thus, early detection of lung cancer is important. When patients are symptomatic at the time of the diagnosis of lung cancer, most probably their disease had already progressed into the later stages of lung cancer. If a smoker has a persistent cough lung cancer should be suspected. However, chronic coughing is not always a symptom of lung cancer.




Lung Cancer, Malignant Neoplasm of Lung




When the cancer initially developed in the lung it is called a primary lung cancer. When the cancer came from other parts of the body and invaded the lung it is called a metastatic lung cancer. Lung cancer includes all types of cancer that develop in the different types of cells of the lungs. 




The syndromes of lung cancer can be categorized into syndromes caused by the tumor itself, syndromes caused by the metastasis of the cancer to the surrounding tissues, syndromes caused by distant metastasis, and paraneoplastic syndromes not caused by metastasis. In many cases, when patients with lung cancer start having symptoms, they already have the progressed form or advanced stage of lung cancer. The diagnosis of lung cancer can be made by:


1) the detection of new symptoms or a change in the health status of patients who already have other types of respiratory disease,

2) accidental detection of the cancer at a health check up,

3) the detection of systematic symptoms such as weight loss or fever, and

4) the detection of symptoms of distant metastasis. If the lung cancer was accidentally detected in a usual health check up, it could be at a relatively earlier stage of the disease. For other cases, full recovery is improbable since the patients are usually found at the later stages of the disease. Based on the location of the cancer, lung cancer can be divided into 2 categories: central lung cancer and peripheral lung cancer. The frequent symptoms in central lung cancer are coughing, hemoptysis, difficulty of breathing, and chest pain. If a smoker has a persistent cough, there is possibility that he has lung cancer. Although coughing is a common symptom, it is a nonspecific symptom and in many cases may be disregarded. Hemoptysis in central lung cancer presents as a small amount of blood at the end of coughing mixed with the viscous sputum. If a bronchus is blocked by a tumor, the portion of the lung affected cannot function properly causing shortness of breath and the production of a hissing sound during breathing. If the cancer developed inside of a bronchus, the chest X-ray film could be interpreted as normal making this type of cancer difficult to detect. If lung cancer invades bronchi or neurons surrounding blood vessels, a heavy dull pain may be felt, but in most cases the pain is not that severe. Unlike in central lung cancer, patients with peripheral lung cancer often do not show any respiratory symptoms at all. Thus, many cases of peripheral lung cancers are accidentally found during regular health check ups or during consults for symptoms of weight loss and body fatigue. 


Cause, conditions and physiological


The most important cause of lung cancer is smoking. It is not an exaggeration to say that more than 90% of deaths in male lung cancer patients are related to smoking. Compared to nonsmokers, the risk of developing lung cancer in smokers is several times higher and this risk is proportional to the amount of cigarettes smoked. Although air pollution can contribute to the development of lung cancer, it is not as detrimental as cigarette smoking.

The risk of developing lung cancer is higher in people who have close relatives who developed lung cancer. It is unclear whether this phenomenon is due to genetic reasons or due to the similarity in circumstances to which they were exposed. Also, several lung cancer causing carcinogenic substances related to occupation have been identified and these include: arsenic, asbestos, chromium, nickel, and radiation.




If a smoker has a persistent respiratory symptom, he should initially suspect the possibility of lung cancer. There is no definite 100% accurate early-detection method for lung cancer. As in the case of gastric cancer, the progression of lung cancer in patients who have tumors smaller than 2 cm is relatively satisfactory. Recently, many trials have been made to achieve early diagnosis of lung cancer in smokers who have high risks for cancer. The usual practice to enable early detection of lung cancer is to conduct a chest X-ray and sputum analysis every 3~6 months. To confirm for the presence of cancer in suspicious patients computed tomography and bronchoscopy are done. The procedure for the diagnosis of lung cancer is initially started from the investigation of abnormal chunks inside the lung and bronchi. A chest X-ray image is taken to observe for the presence of a possible tumor which can be confirmed by computed tomography. If the chest X-ray image was found to be normal, computed tomography or bronchoscopy is used for the possibility that the tumor is inside the bronchi. Bronchoscopy is done to observe the suspected region by inserting a camera attached to a long line into the airway, similar to the procedure done in gastroscopy. When an abnormal mass is found, it has to be identified whether it is cancer or not. For screening, tissue tests are conducted. If the sputum test does not reveal the nature of the mass, a portion of the chunk has to be directly detached for further analysis. After confirming the presence of lung cancer and identifying the type of cancer cell involved, the progression of the disease is assessed through the degree of metastasis. Based on the results of the screening tests for metastasis, the stage of the cancer and the appropriate treatment are determined.  


Progress, prognosis


Since the progression of lung cancer depends upon the cancer type and the stage of cancer, the prognosis cannot be described uniformly. Among patients on the first stage of disease, 60% could expect full recovery. On the other hand, among patients in the later stages of disease, 90% die within 1 year.




If a patient has lung cancer, surgery is the most appropriate treatment for full recovery. Since the progression of cancer could depend upon the types of cancer cells involved, lung cancer can be classified into small cell carcinoma and non-small cell carcinoma. Lung cancer is classified under any of the 4 stages based on the degree of its progression. From the stage 1 to stage 3 of lung cancer, surgery is performed to remove cancer cells. After surgery, anticarcinogenic drugs and radiotherapy may be used if necessary. The 5 year survival rate ranges from 40 to 60%. Metastasis to other organs occurs in a fast rate for small cell carcinoma. Even if the cancerous mass was removed by surgery, patients with this cancer can still die due to the fast transmission of the cancer to other organs. For this reason, the anticarcinogenic drug therapy and radiotherapy are usually done instead of surgery.




Avoidance of smoking is the optimum measure in the prevention of lung cancer. If a smoker who usually smokes less than a pack of cigarettes a day quits smoking, his chance of having lung cancer will be the same as that of nonsmokers after 10 years of quitting smoking. However, a study suggested that even if a smoker who smokes more than 1 pack of cigarettes a day quits smoking, his risk for developing lung cancer after 10-20 years would still be more than 2 times higher than that off non-smokers. Regionally and nationally, the incidence of lung cancer corresponds to the cigarette consumption rate of 20-30 years ago. In the smoke of cigarettes, approximately 3,800 types of chemical substances are present and the inhalation of these carcinogenic substances can cause lung cancer. Among the various types of lung cancers, squamous cell carcinoma and small cell carcinoma have the closest association with smoking.


1Consult a doctor in the following cases


For the following cases, it is recommended to visit a hospital.


- If a smoker has a persistent cough.

- When blood is mixed with sputum

- When experiencing shortness of breath or having hissing sound while breathing.

- If a heavy dull pain is felt in the chest

- When lumps are felt around neck and armpit.

- If voice is husky and not returning to normal.

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