New MRI technology bypasses need for biopsy for renal cell cancer

Investigators have developed an MRI technology that can provide information about the nature and aggressiveness of clear cell renal cell carcinoma (ccRCC) without a biopsy. The findings were published in The Journal of Urology.

While renal mass biopsy (RMB) is highly accurate for diagnosis of ccRCC, it is an invasive procedure that can cause pain, anxiety, discomfort, and other adverse effects. In addition, it does not provide information in 14% of cases, and it is unreliable for tumor grade determination. As a result, some patients elect to avoid the biopsy and take a “wait and see” approach.

The research team, led by Noah Canvasser, MD, of the Kidney Cancer Program at UT Southwestern Harold C. Simmons Comprehensive Cancer Center in Dallas, Texas, developed multiparametric MRI (mpMRI) protocols that indicate tumor aggressiveness with high confidence and allow for evaluation of the chemical composition of the tumor without a biopsy.

The investigators retrospectively reviewed the records of patients with cT1a renal masses who had MRI and partial or radical nephrectomy. Seven radiologists with varying levels of experience (from 1 to 15 years) independently reviewed each record. They were blinded to final pathology reports.

The radiologists applied a score that indicated the likelihood of clear cell RCC (ccRCC), ranging from 5 (definitely) to 1 (definitely not). They each received a refresher training session with examples of features of ccRCC histology.

A total of 110 patients with 121 cT1a renal masses were identified. The mean tumor size was 2.4 cm, and 61 (50%) of the lesions were ccRCC. Combining all seven MRI readers provided 79% mean accuracy. Defining clear cell as scores of 4 or greater demonstrated 80% specificity. Scores of 3 or greater showed 95% sensitivity. Interestingly, the radiologists’ years of experience did not correlate with improved diagnostic accuracy. Interreader variability was moderate to good.

The new mpMRI can be an appealing alternative to RMB because it can provide pathological information that can help with managing the disease, as well as anatomical information required for surgical planning.

One limitation of the study was the retrospective design, which has inherent selection bias. In addition, while the interreader variability had good consistency among the radiologists using the algorithm, standardization is needed to specify imaging protocols between centers. The investigators noted that future studies should be larger and multi-institutional.

“A clear cell likelihood score used with magnetic resonance imaging can reasonably identify clear cell histology in small renal masses and may decrease the number of diagnostic renal mass biopsies. Standardization of imaging protocols and reporting criteria is needed to improve interobserver reliability,” the authors concluded.

To read more about this study, click here.