According to recent research, it may be possible to measure levels of aquaporin-1 (AQP1) and perlipin-2 (PLIN2) in urine and identify kidney cancer in an early and more treatable stage.

In a recent report published in JAMA Oncology researched indicated that these proteins may be used as specific diagnostic and screening biomarkers for clear cell or papillary renal cell carcinoma (RCC).1 This urine test may also be highly beneficial in the differential diagnosis of imaged renal masses.

“The clinical implications include, but are not limited to, the ability to inexpensively, routinely screen patients for kidney cancer, or at least at-risk patients such as smokers or groups that had been exposed to environmental contaminants in their drinking water known to be associated with increased risk of kidney cancer,” said principal study investigator Jeremiah Morrissey, PHD, a professor of anesthesiology at Washington University School of Medicine in St. Louis, MO.

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Currently, screening for asymptomatic renal tumors with abdominal imaging is not believed to be cost-effective. In addition, abdominal imaging cannot reliably distinguish benign from malignant tumors.

Dr. Morrissey and his team evaluated the clinical utility, sensitivity, and specificity of urine AQP1 and PLIN2 concentrations as unique noninvasive biomarkers to diagnose malignant clear cell or papillary RCC.

They obtained samples from 720 patients undergoing routine abdominal CT (screening population), 80 healthy controls, and 19 patients with pathologically confirmed RCC.

The researchers measured urine AQP1 and PLIN2 concentrations by sensitive and specific ELISA and Western blot procedures in all groups.

They found that urine AQP1 and PLIN2 concentrations in the 19 patients with known RCC were significantly higher than the 80 healthy controls.

The AQP1 and PLIN2 concentrations individually or in combination were found to have 95% or greater sensitivity and 97% or greater specificity compared with controls or the screening population.

Study co-investigator Evan Kharasch, MD, PHD, of Washington Universtiy Schhol of Medicine in St. Louis, MO, said in the current era 80% of patients survive RCC.

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However, early diagnosis is a challenge and patients with metastatic RCC have high mortality rates. Dr. Kharasch said more than 80% of patients die within 5 years if they are diagnosed late in the course of the disease. Dr. Kharasch said kidney cancer is commonly detected through an incidental, fortuitous finding when an individual has a CT or MRI scan.

He said it is not affordable to use these scans as a screening method so his team has been pursuing a noninvasive approach.

Overall, the researchers found that the protein biomarkers were more than 95% accurate in identifying early-stage kidney cancers and there were no false positives caused by non-cancerous kidney disease.

Dr. Morrissey said each biomarker individually pointed to patients who were likely to have RCC, but the two biomarkers together were more sensitive and specific than either alone.