Certain preoperative and patient characteristics increase the probability of an unplanned conversion from partial to radical nephrectomy, a new study finds.

Investigators matched 168 cases to 168 controls by tumor size, surgical approach, and year of surgery. On multivariable analyses, posterior or middle tumor location and hilar location increased the odds of conversion by 2.8-, 6.4-, and 5.6-fold, respectively, R. Houston Thompson, MD, of Mayo Clinic in Rochester, Minnesota, and colleagues reported in The Journal of Urology. These particular features do not contribute to the overall RENAL Nephrometry Score but “should be preferentially considered when evaluating the risk of conversion,” they wrote.

Male sex was significantly associated with 2.3-fold increased odds of conversion, the investigators reported. They suggested that men have more adherent perinephric fat, which is difficult to dissect, compared with women.

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In line with previous reports, the investigators also found that each increment in Charlson comorbidity score significantly increased the odds of conversion by 1.3-fold.

The most common reasons for conversion from partial to radical nephrectomy tumor were upstaging (44%), insufficient remaining viable renal parenchyma (27%), and positive surgical margins (11%), according to Dr Thompson’s team. The conversion rate declined from 13% in 2000-2003 to 4% in 2012-2015.

“This study is the largest cohort to identify specific patient and tumor factors that may affect the risk of conversion from PN to RN,” John Roger Bell, MD, and Jason Bylund, MD, MPH, University of Kentucky College of Medicine in Lexington, commented in an accompanying editorial. “These data may help to revise renal tumor scoring systems, and may assist urologists in surgical planning as well as patient counseling.”

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.


Tsivian M, Joyce DD, Packiam VT, et al. Unplanned conversion from partial to radical nephrectomy: An analysis of incidence, etiology, and risk factors. J Urol. 208(5):960-968. doi:10.1097/JU.0000000000002837