Good news that the follow-up CT scans were negative. Multiple sub-centimeter pulmonary nodules are unlikely to be indicative of lung cancer, but more likely to be a sign of spread of your father’s kidney tumor. However, one must be cautious in the interpretation of positive positron emission tomography (PET) scans, since there are degrees of positivity based on the standard uptake value (SUV), a cut-off point of >2.5 deemed to be significant. An initial SUV of less than 2.5 in geographic regions with epidemic granulomatous disease such as tuberculosis (TB) or fungal infections is not useful for differentiating benign from malignant pulmonary nodules. I am not an expert on this, so you should discuss this with the radiologist whose report stated “…suspicious for metastases”.