Fibrous foci in both lungs are usually not advanced stage of lung cancer. Fibrous foci in lungs are the result of chronic inflammation, which is described by imaging, and they are most commonly seen in tuberculosis, recurrent lung infections and other causes, which lead to long time of exudation in lungs and formation of fibrous foci. The manifestation of lung cancer is usually not fibrous foci, but it cannot be excluded that some patients with tuberculosis have concomitant lung cancer in the same area on the basis of tuberculosis. In conclusion, if you see fibrous foci on chest X-ray or CT, it usually indicates that it is an old lesion, not lung cancer. However, if it is accompanied by other symptoms, or if you find that the fibrous foci are expanding with changes such as burr-like and exudation during regular follow-up, you should consider whether it may be combined with lung cancer.