Urine Test for Early Detection of Renal Cell Carcinoma?

Measuring levels of two urine proteins may provide a noninvasive approach for early detection of renal cell carcinoma (RCC), reports a study in JAMA Oncology.

Urine specimens were obtained from a convenience sample of 720 patients undergoing abdominal computed tomography (CT) for various indications, and from 19 patients with pathologically confirmed RCC and 80 healthy control individuals. Two urine proteins—aquaporin-1 (AQP1) and perilpin-2 (PLIN2)—were evaluated as biomarkers of early RCC. Previous studies showed that these proteins are elevated in patients with RCC but not in those with nonmalignant kidney disease. Renal masses and RCC were confirmed by CT scans and postnephrectomy examination, respectively.

The median urine AQP1 level was 225.0 ng/mg urine creatinine in patients with confirmed RCC versus 1.1 ng/mg in healthy control individuals. The values for PLIN2 were 37.8 versus 3.1 absorbance units/mg creatinine, respectively. In the screening population, the median AQP1 value was 0.5 ng/mg, and the median PLIN2 value was 0 absorbance units/mg.

For the two biomarkers alone or in combination, the area under the receiver operating characteristic curve was at least 0.990. Sensitivity was at least 95 percent and specificity at least 91 percent in comparison with control individuals and the screening population. Three patients in the screening population had biomarker levels suggesting RCC. All three had a renal mass shown by CT scan, and two had pathologically confirmed RCC.

The results validate the clinical utility of urine AQP1 and PLIN2 as biomarkers for early and noninvasive detection and screening for RCC. These proteins may also be useful for the differential diagnosis of renal masses seen on imaging studies [Morrissey JJ, et al. Evaluation of urine aquaporin-1 and perilipin-2 concentrations as biomarkers to screen for renal cell carcinoma: a prospective cohort study. JAMA Oncol Published online March 19, 2015. doi:10.1001/jamaoncol.2015.0213].