Early diagnosis is key to successful outcomes for kidney cancer patients but remains a challenge for the field as common symptoms, such as blood in the urine and abdominal pain, often do not develop until later disease stages. When kidney tumors are diagnosed at an advanced stage, >80% of patients die within 5 years. However, a promising noninvasive screening method for kidney cancer has been developed by researchers from Washington University in St Louis School of Medicine (MO, USA). The study, which involves the detection of proteins in urine, is published in JAMA Oncology.
In an effort to detect kidney tumors earlier, the researchers measured levels of aquaporin-1 and perlipin-2 proteins in urine samples from 720 patients due to undergo abdominal CT scans for reasons not related to suspicions of kidney cancer. The results of these scans were then analyzed by the investigators to determine kidney cancer presence.
These data were then compared with healthy controls (n = 80) and confirmed kidney cancer patients (n = 19), from which researchers observed elevated levels of both proteins in the urine of patients with kidney cancer. The two markers were calculated to be >95% accurate in identifying early-stage kidney cancers. In addition, no false positives due to noncancerous kidney disease were observed.
Three of the 720 patients who received abdominal CT scans also had elevated levels of both proteins in their urine. Two of those patients were subsequently diagnosed with kidney cancer, and the third patient died from other causes prior to diagnosis.
“These biomarkers are very sensitive and specific to kidney cancer,” explained senior author Evan Kharasch (Washington University in St Louis School of Medicine). Putting these findings in context, he stated: “The most common way that we find kidney cancer is as an incidental, fortuitous finding when someone has a CT or MRI scan. It’s not affordable to use such scans as a screening method, so our goal has been to develop a urine test to identify kidney cancer early.”
Highlighting the potential of these markers, Kharasch continued: “Patients with other kinds of cancer or other kidney diseases don’t have elevations in these biomarkers, so in addition to being able to detect kidney cancer early, another advantage of using these biomarkers may be to show who doesn’t have the disease. Not all kidney masses found by CT scans turn out to be cancerous; in fact, about 15 percent are not malignant. But a CT scan can only tell you whether there is a mass in the kidney, not whether it’s cancer, currently, the only way to know for sure is to have surgery, and unfortunately, 10–15% of kidneys removed surgically turn out not to be cancerous.”
The researchers hope that their findings will be rapidly developed into a clinical test to allow earlier identification of kidney cancers and thus potentially improve patient outcomes.
Sources: Morrissey JJ, Mellnick VM, Luo J, et al. Evaluation of Urine Aquaporin-1 and Perilipin-2 Concentrations as Biomarkers to Screen for Renal Cell Carcinoma. JAMA Oncol. doi:10.1001/jamaoncol.2015.0213 (2015) (Epub ahead of print); Washington University in St. Louis Press Release