Many patients have the feeling that lung cancer is already in the middle to late stage when it is detected, and it is rarely detected in the early stage. In fact, this is true. Statistics show that about 85% of lung cancer patients have already metastasized by the time they are seen, and only about 15% of them still have a chance for surgery! So, is there really no way for us to detect lung cancer earlier? To figure out this question, we need to have a basic understanding of lung cancer. Lung cancer is a solid tumor that occurs in the lung. When it starts to grow, most patients do not have any symptoms. As the tumor grows, the patient’s symptoms only start to appear gradually, such as coughing, coughing blood, chest pain, chest discomfort, etc., while the tumor has been growing for a long time and has enough time and opportunity to develop metastasis. In other words, the time to detect lung cancer in early stage should be when there are no symptoms or when the symptoms are mild. Okay, the next question is, what is the method of chest examination when there is no symptom? Chest X-ray or chest x-ray? Obviously not. Studies have shown that chest radiographs have a 35% or higher detection rate for early stage lung cancer, and chest x-rays have an even higher rate! There is sufficient evidence that chest CT is quite sensitive in detecting early lung cancer, and that screening lung cancer with chest CT can reduce the overall mortality rate of lung cancer by 20% compared to chest X-ray; and a study by the European Early Lung Cancer Action Plan (I-ELCAP) showed that lung cancer detected by low-dose spiral CT screening had a 10-year survival rate of 92% after early surgery! The results are quite satisfactory. One last question, what kind of people need a CT chest screening? This is actually a question of defining the high-risk group for lung cancer. For those who have smoked heavily for a long time (smoking index over 400-600 cigarettes per year), have a close family member who has had lung cancer, or have a history of chronic lung disease, or are over 55 years old, these are all high-risk groups for lung cancer. Of course, chest CT is essential for those patients who present with cough, especially with coughing up blood.