A new radioactive tracer agent can be used with positron emission tomography/computed tomography (PET/CT) to accurately detect clear cell renal cell carcinomas (ccRCC), the most common type of kidney cancer.

This open-label study was conducted at 14 medical centers, and led by Chaitanya Divgi of Columbia University Medical Center. The investigators compared results from two imaging methods in 195 patients with renal masses who were scheduled for nephrectomies: iodine-124 (124I)-girentuximab PET/CT and contrast-enhanced CT scans (CECT). 124I-girentuximab binds to an antigen that is found on the cell surface of nearly all ccRCC.

The 124I-girentuximab PET/CT tests were more sensitive than CECT (average sensitivity of 86.2% vs 75.5%) and more specific (average specificity of 85.9% vs 46.8%) for detecting ccRCC tumors. 124I-girentuximab was well tolerated. Three blinded readers interpreted the images for each imaging modality, and both inter-reader and intrareader agreement was high for both the PET/CT and CECT imaging methods.

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If the results are confirmed by additional studies and the test is approved by the FDA, the new diagnostic test could lessen the need for more invasive procedures, including needle biopsies and nephrectomies. 124I-girentuximab PET/CT may help practitioners decide how best to treat a patient may have a particular benefit for patients who are frail, elderly, or have other health conditions that make surgery risky.

The authors commented that this study is the first clinical validation of a molecular imaging biomarker for malignancy, to their knowledge.

This study was published in the Journal of Clinical Oncology (2012; doi:10.1200/JCO.2011.41.2445).