Proliferative foci in the lungs belong to the residues after the absorption of inflammation, and it is not completely certain how long it will become cancerous. From the overall clinical point of view, most of the foci will not become cancerous; a small part of the foci will become cancerous, and the probability of it is very low, and the specific time cannot be determined. 1. The proliferative foci themselves belong to the residual fibrous tissue, which are stable lesions. From the clinical point of view, the probability of cancer is very small, and most of the lesions are non-cancerous. 2. In a small number of cases, because of local scar formation, the tissue cells may be abnormal, and under special circumstances, there will be obvious abnormal cell proliferation, which will lead to cancer, and there is no way to determine the specific time. Overall, the presence of proliferative foci in the lungs does not require much concern, and regular annual screening lung CT through physical examination is sufficient, as long as there is no change, no special treatment. As long as there is no change, there is no need for special treatment. Once the foci continue to increase in size with the formation of soft tissues, it is necessary to consult a doctor in time for observation and standardized treatment under the guidance of the clinician.