Patient: Small nodule in the lower lobe of the right lung, with a history of breast cancer, is it metastatic? Generally speaking, small nodules in the lung less than 5mm only need follow-up, 5-10mm need observation or anti-inflammatory treatment for a period of time to see if there is any change, 10-15mm need close observation and regular review of chest CT, if it reaches 15mm or more, surgical intervention is needed. If it reaches 15mm or above, surgical intervention is needed. Because some of the small nodules are precancerous lesions.