New Approach May Spare Some with Kidney Cancer from Undergoing Surgery

A new approach to assessing kidney tumors could save thousands of patients from risky surgery each year, according to study findings published in Clinical Cancer Research.

Researchers from Roswell Park Comprehensive Cancer Center in Buffalo, New York, discovered a way to use CT imaging to determine if a tumor is benign or malignant — a diagnosis typically not made until the tumor is removed.

They examined 124 patients who either had renal oncocytoma, a benign kidney tumor, or chromophobe renal cell carcinoma, a potentially life-threatening form of kidney cancer. Both tumors test positive for the CD117 biomarker and look nearly identical under a microscope when biopsied, according to researchers.

“Doctors have for years struggled to tell whether a renal tumor diagnosed by radiologic approaches is cancerous or benign, and needle-core biopsy has failed to prove beyond all doubt that a benign tumor is not in fact cancer,” Eric Kauffman, M.D., assistant professor of oncology in the Department of Urology at Roswell Park Comprehensive Cancer Center, said in an interview with CURE.

“Accordingly, it remains common practice for urologists to skip the biopsy altogether and simply remove the tumor surgically, just to be safe,” he added. “Reliable diagnosis of renal oncocytoma preoperatively is significant because it will avoid the need for a surgery to make the diagnosis.”

Surgery has disadvantages, including frequent complications when the surgeon attempts to remove just the tumor and save the kidney, noted Kauffman.

“These complications can include, for example, bleeding that requires transfusions, internal urine leakage that leads to additional procedures, loss of the kidney and loss of kidney function even when the kidney can be saved, in addition to stress on the heart and lungs typical of any major surgery,” he said. “Loss of kidney function has been linked to serious heart problems, among other health issues. Furthermore, benign kidney tumor operations and their complications incur a significant cost to the health care system, with annual estimates approaching as high as $100 million in the United States alone.”

Researchers found that chromophobe renal cell carcinoma was associated with a large tumor size and in younger patients compared with renal oncocytoma that presented with multiple tumors. But, according to researchers, the most reliable information came from using CT scanning, which they called tumor-to-cortex Peak Early-phase Enhancement Ratio (PEER).

First, researchers performed a CT scan without using contrast dye. Then, a second scan was done as the contrast dye was entering the kidney. They based their diagnosis on the brightness of the tumor.

“When the tumor is bright compared to the surrounding kidney, it is a benign oncocytoma,” Kauffman said. “When the tumor is dark relative to the surrounding kidney, it is a chromophobe kidney cancer. However, this rule only applied with 100 percent accuracy when the tumors were CD117 positive (as most oncocytoma tumors and chromophobe cancers are). Hence, the PEER tool will only be useful to patients who have biopsied kidney tumors with CD117 positivity.”

Four cases were misclassified as benign when they were cancerous. However, researchers noted that these tumors were negative for the CD117 biomarker.

Going forward Kauffman feels confident in using this approach within his clinical practice but said that additional testing is needed from other centers to make sure it can be replicated there.

“Among the most promising and exciting aspects of our discovery is that it does not require any special type of contrast CT,” said Kauffman. “In fact, we evaluated CT scans from many different imaging facilities, all using somewhat different protocols, and it didn’t matter — the scoring approach was reliable in all cases. The fact that no standardized CT protocol is needed suggests that the PEER approach can be easily adapted at other centers.”