Tumor location and body mass index (BMI) may be useful for identifying which renal tumors are likely to be benign prior to surgery, according to researchers.

In a study of 316 patients who underwent nephron-sparing surgery (NSS), investigators found that peripheral tumor location on the kidney and lower BMI were independently associated with benign tumor histopathology at the time of surgical resection.

Patients in the study underwent NSS for suspicious renal masses measuring less than 7 cm. Of the 316 patients, 76 (24%) had benign tumors.

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Patients whose tumors were in a peripheral location had a twofold increased likelihood of having benign histology, Bruce R. Kava, MD, Associate Professor of Urology at the University of Miami Miller School of Medicine, and colleagues reported online in International Urology and Nephrology. Those with a BMI below 25 kg/m2 were 50% more likely to have benign histology than patients with a BMI of 25 or greater.

Additionally, women were nearly four times more likely than men to have benign histology. Among the 137 women in the study, 52 (38%) had benign histology and 85 (62%) had malignant disease. In contrast, among the 188 men in the study, only 27 (14%) had benign disease and 161 (86%) had malignant disease.

“Incorporation of these variables [tumor location and BMI] with previously validated clinical variables is likely to improve the performance of any future nomograms in predicting which renal tumors are likely to be benign,” Dr. Kava’s group concluded. “Select patients may ultimately avoid surgical resection as a result.”