Lung cancer is one of the most common malignant tumors and is located at the top of the list of causes of cancer death. Surgery is considered to be the only treatment with the possibility of curing lung cancer, but unfortunately, about 80% of patients have already lost the chance of surgery when lung cancer is detected, which seriously affects the treatment outcome of lung cancer. How to detect lung cancer early becomes a key factor to improve the survival rate of lung cancer patients. There are no specific symptoms in early stage of lung cancer, which makes the early detection of lung cancer difficult. For the initial examination and diagnosis of lung cancer, chest X-ray or chest CT examination is inseparable. Generally speaking, chest CT is mostly thin spiral CT, which rarely misses lung lesions; but not chest X-ray, which is often difficult to detect if the lesions are small or low density. But difficult to detect does not mean that it cannot be detected. In our clinical work, we often encounter patients with lung cancer who had chest radiographs taken a year or several years ago, which provides us with a convenient way to trace the development of lung cancer. Careful review of these chest films reveals that although no definite masses or nodules can be seen, some “traces” can be found in the current location of the tumor, some of which are irregular slightly dense shadows, some are similar to localized coarse lung texture, although the scope is small and fuzzy, they can be seen to be different from other areas. The difference is visible. Unfortunately, these minor abnormalities are ignored as atypical inflammation or artifacts caused by other reasons, and further examination is abandoned, and the opportunity to cure lung cancer at an early stage is also lost. Therefore, if a chest radiograph is done under physical examination or other circumstances and some minor abnormalities are found on the chest radiograph that cannot be easily explained, further CT examination is recommended for these “clues”. Although this practice has the risk of “killing a thousand by mistake”, it is after all a responsible attitude towards life. If the tumor is detected early, the survival rate after surgery is very good. In Japan, because doctors do not let go of any traces on chest films, and the national health awareness is also very strong, so the use of CT is very high, screening a large number of so-called GGO (ground glass opacity) lesions and confirmed to be lung cancer patients, these patients have a 5-year survival rate of 100% after surgery; and from “According to the International Early Lung Cancer Action Plan, 85% of lung cancers detected by annual low-dose CT screening are very early stage, and after early surgical resection, the 10-year survival rate after surgery is 92%! In our country, since chest X-ray is far more popular than CT, any slight abnormality on a regular chest X-ray should be taken seriously and should not be paralyzed, otherwise, you may lose a chance to cure lung cancer!