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1 The death rate due to cancer of the lungs has increased more than 800 percent in males and has more than doubled in females during the last 25 years. It is considerably higher in urban and industrial areas than in rural districts. There are many possible causes, but it is still controversial which are most blameworthy. Those factors which have been mentioned most frequently are the presence of foreign particles and other irritants in the air (smoke particles, smog, exhaust fumes), and the smoking of cigarettes and cigars.
2 Numerous studies have demonstrated a striking correlation between the death rate from lung cancer and smoking habits. Among heavy smokers—21 to 30 cigarettes per day—the mortality rate from lung cancer is nearly 17 times the rate from nonsmokers. It is expected that the death rate among women will increase as the present high rate of smoking among women has its effect.
3 Sometimes cases of lung cancer are discovered at the time when an X-ray is taken for the purpose of detecting tuberculosis. Too often, however, a current emphasis upon the danger of exposure to radiation from X-ray machines can frighten people away from routine chest X-rays and thus prevent an early diagnosis of lung cancer. Early detection is absolutely essential if any possibility of cure is to be maintained. Modem X-ray machines in competent hands pose such slight danger, at least to those over 40 years of age, that this would be much more than offset by the advantages of discovering a tumor while it is small enough to be completely removed.
4 A common form of lung cancer is bronchogenic carcinoma, so-called because the malignancy originates in a bronchus. The tumor may grow until the bronchus is blocked, cutting off the supply of air to that lung. The lung then collapses, and the secretions trapped in the lung spaces become infected, with a resulting pneumonia or the formation of a lung abscess. Such a lung cancer can also spread to cause secondary growths in the lymph nodes of the chest and neck as well as in the brain and other parts of the body. The only treatment that offers a possibility of cure, before secondary growths have time to form, is to remove the lung completely. This operation is called pneumonectomy.
5 Malignant tumors of the stomach, the breast, the prostate gland and other organs may spread to the lungs, causing secondary growths.

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A. Common Secondary Lung Cancers
B. The Advantages Brought about by Routine Chest Checkup
C. Relationship between Mortality Rate from Lung Cancer and Smoking Habits
D. Operable and Inoperable Lung Cancers
E. The Increasing Death Rate from Lung Cancer and Possible Causes
F. An Ordinary Type of Lung Cancer

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填空题 Routine X-ray chest examination is not so dangerous 1.
A. before the cancer cells spread elsewhere
B. the more chances of dying of X-ray radiation he will have
C. what is most responsible for lung cancer
D. as some people imagine
E. the more chances of getting lung cancer he will have
F. which form of lung cancer is a common one

填空题 A primary lung cancer patient may be cured by removing the lung completely 1.

填空题 People are still not sure 1.

填空题 The more cigarettes one smokes, 1.