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Study validates radiographic measure to differentiate renal oncocytoma, chromophobe renal cell carcinoma tumors
Investigators validated a reproducible radiographic measure that differentiates between CD117-positive renal oncocytoma and chromophobe renal cell carcinoma tumors.
“The take-home message of the study is that we have developed a much-needed novel approach to accurately identify benign renal oncocytoma tumors using a combination of biopsy, biomarker immunostain and CT imaging,” Erik C. Kauffman, MD, a study co-author, staff physician and assistant professor of oncology in the department of urology at Roswell Park, told Healio.com/Nephrology. “This approach may allow all benign renal oncocytomas that test positive on biopsy for the CD117 biomarker, which is the vast majority of them, to be diagnosed without the need for major surgery to rule out cancer.”
He added, “This approach could thus spare thousands of patients with benign renal tumors from undergoing unnecessary surgery in the U.S. each year. However, before wide-spread use is implemented, additional testing is needed at other centers to ensure it is 100% accurate in their hands as well.”
Researchers studied 87 patients undergoing nephrectomy and had 53 renal oncocytoma and 34 chromophobe renal cell carcinoma (ChRCC) tumors. Investigators identified clinical and radiographic variables correlated with renal oncocytoma vs. ChRCC in patients treated between 2003 and 2012. A prospective validation was conducted in consecutive renal oncocytoma and ChRCC tumors resected between 2013 and 2017.
Investigators found tumor size and younger age correlated with ChRCC. Multifocality was associated with renal oncocytoma. However, the tumor-to-cortex peak early-phase enhancement ratio (PEER) using multiphase CT was the most reliable variable to differentiate between ChRCC and renal oncocytoma. Of the 54 PEER-evaluable tumors, PEER classified each correctly as either ChRCC or renal oncocytoma. However, there were four CD117-negative ChRCC variants that were misclassified.
Results from the prospective PEER study demonstrated 100% accuracy of renal oncocytoma and ChRCC classification in 22/22 additional CD117-positive tumors. PEER scoring had “excellent” prospective interobserver reproducibility and was ideal for renal oncocytoma and ChRCC assignment, according to researchers.
“Furthermore, the image assessment is relatively fast, and the raw scores generated were surprisingly similar among different reviewers with different levels of radiologic expertise,” Kauffman said. “All of this suggests that this novel approach should be easily generalizable and implemented at other centers.” -by Monica Jaramillo
References:
Amin J, et al. Clin Cancer Res. 2018;doi:10.1158/1078-0432.CCR-18-0252.