A scoring criterion which can distinguish between benign and malignant tumors in pediatric patients with renal masses could help determine if they can benefit from partial rather than radical nephrectomy (removal of the kidney), according to new study findings.
The RENAL nephrometry score is widely used in cases of adult kidney cancer to determine who might be offered nephron-sparing surgery, but the latter has not traditionally been employed in pediatric patients with renal masses.
“Our number one goal is to treat the cancer, but if we are good enough to get the cancer out but leave enough tissue behind so that the rest of the kidney can function, the better off these children are going to be for the rest of their lives,” the senior investigator of the work, Andy Chang, MD, vice chair of operations for the Department of Surgery at Children’s Hospital Los Angeles, California, told Medscape Medical News.
“We found that low scoring masses are more likely to be nonmalignant tumors and that nephron-sparing surgery can thus be considered in these patients,” he added.
The findings were presented on December 5 at The Societies for Pediatric Urology’s fall congress in Miami, Florida.
Looking Back at Tissue From Total Nephrectomies in Kids
In their study, Chang and colleagues retrospectively examined a total of 148 pediatric patients who had all undergone a total nephrectomy between 2003 and 2021. They evaluated images of their kidneys using the RENAL nephrometry scoring criteria, a standardized system used to report anatomic characteristics of a renal mass.
The score arrived at provides a value and percent risk of complications should nephron sparing surgery be offered to patients.
“As would be expected with pediatric renal lesions, 93.3% of the masses in this cohort were malignant,” Chang reported. The mean mass diameter for malignant lesions was considerably larger, at 10.7 cm, compared with roughly half that, at 5.5 cm, for nonmalignant lesions (P < .001).
Similarly, the mean RENAL score for malignant lesions was 10.3 compared with a mean RENAL score of 9.0 for nonmalignant lesions (P = .001).
“Some nine masses, or 3.4% of all masses, were determined on the RENAL nephrometry score to be amenable for partial nephrectomy,” Chang and co-authors reported.
Indeed, the odds of identifying a nonmalignant mass using the RENAL nephrometry score was over 19 times greater than the odds of finding a malignant lesion (P < .001).
The mean RENAL score for masses that were amenable for partial nephrectomy was also significantly lower, at 7.3, than the mean score of 10.4 for masses that were not amenable to partial nephrectomy (P < .001), the authors note.
“If we see a lesion in a child, there is probably a 90% to 95% chance that it’s going to be cancer — mostly Wilms tumor,” Chang explained. “Because of that, our protocol has been, ‘You just remove the kidney,’ ” he noted, adding that survival rates in children with Wilms tumor are now approaching 90%.
Offering a Partial Nephrectomy
The proportion of pathology specimens taken at surgery that turned out to be nonmalignant was almost 7% in the review
But not all benign tumors in the current analysis could have been treated with nephron-sparing surgery, because 64% of them were so large they were not amenable to a partial nephrectomy, Chang explained.
This is how the researchers ended up with the 3.4% of masses identified as possibilities for nephron-sparing surgery.
“We need to refine our treatment of pediatric kidney cancer, because quality of life could be better for our patients, and we need to start thinking about partial nephrectomies and nephron-sparing surgery for [certain] pediatric patients as well as for adults,” Chang noted.
The study was funded by Merck. Chang had no conflicts of interest to declare. Smith reports receiving grant funding from Merck. Jones reports no relevant financial relationships.
The Societies for Pediatric Urology: Presented December 5, 2021.