<h4>Rationale</h4>Carbonic Anhydrase IX (CAIX) positron emission tomography (PET) is an accurate and non-invasive imaging modality for the detection and characterisation of clear-cell renal cell carcinoma (ccRCC) but evidence in the setting of high-risk renal cancer is lacking. Here, CA9 is linked to nonpapillary renal cell carcinoma.