Program Director of the UCSD Cancer Center Urologic Oncology Fellowship, Dr. Ithaar Derweesh, co-authored and published an analytical paper in the British Journal of Urology on July 3, after concluding a retrospective study by comparing a 168-man group of patients who had partial kidney removal to a 264-man group who had complete kidney removal.

Patients who had complete kidney removal were 3.5 times more likely to develop erectile dysfunction compared to those who had kidney reconstruction; this is a normalized value that takes factors like pre-existing cardiovascular problems into consideration. After about six years, 29.5 percent of the men in the latter group developed erectile dysfunction. Only 9.5 percent of those who had partial kidney removal developed the dysfunction.  

Kidney removal, or “nephrectomy,” is usually performed on patients with seriously damaged or diseased kidneys. Urological experts agree that the partial procedure is optimal for those with small, single tumors.

“We’ve been finding more and more patients with earlier stage disease and smaller tumors,” Derweesh said. “With that comes the recognition that removal of a significant amount of kidney tissue may actually be increasing the risk of kidney disease and other diseases.” Prior research led by Dr. Derweesh has shown that partial nephrectomy also decreases the risk of osteoporosis and chronic kidney insufficiency in patients. In April, Dr. Derweesh published a paper citing findings that partial nephrectomy means a significantly higher likelihood of anemia onset.

“Generally, even for tumors that are two centimeters and below, the rates for partial nephrectomies — even though it has gone up in recent years — is still about 40 to 50 percent and I would say that is a gross underutilization of the procedure,” Derweesh said. Two-thirds to three-fourths of kidney removal surgeries performed at UCSD are partial nephrectomies, according to Lead Author of Study and Chief Resident, UCSD School of Medicine, Division of Urology, Dr. Ryan Kopp.

Researchers from the study include local experts, professionals from the University of Tennessee Health Science Center and other UCSD scientists.

“A question that is important to us is whether or not there is a threshold at which partial nephrectomy no longer infers a benefit, and we intend to look into that,” Kopp said.

Further research may take place soon, pending additional funding from the Sexual Medicine Society of North America.

“We’re in the process of putting together grant proposals for prospective studies that will further analyze the interrelationship between kidney surgery and various metabolic and cardiovascular consequences and we will also see what measures we may be able to take to prevent these,” Derweesh said.