There is no clear clinical statistical conclusion on how long it takes for a 3mm lung nodule to develop into lung cancer. Whether a lung nodule will become cancerous or not is related to the nature of the nodule and the cause of the nodule, and is purely not positively correlated with the time. Lung nodules do not necessarily become cancerous. Generally speaking, the smaller the diameter of lung nodules, the lower the probability of cancer. Lung nodules with a diameter of less than 3mm or a maximum diameter of less than 5mm belong to lung nodules with a very low probability of malignancy. Nodules with a diameter of more than 0.8 to 1 cm and uneven density, with hairy glass components and lobulated shape have a relatively high probability of malignancy. Therefore, don’t worry too much about 3mm lung nodule, if there is no clinical symptom, regular review of lung CT is enough. If the nodule becomes bigger or the edge becomes rough, you can consider doing a puncture biopsy of the lung nodule, and perform surgery if necessary.