New research concludes that removing just part of the kidney yields higher five-year survival rates in kidney cancer patients than removing the entire kidney and offers an explanation as to why partial nephrectomy should likely be preferred.
The authors of the study, published in the most recent issue of the Journal of the American Medical Association (2012;307:1555-1657), note that although partial nephrectomy has been the preferred treatment method because it is associated with a lower risk of chronic kidney disease, recent clinical trial data suggesting that full nephrectomy offers better patient outcomes has reopened the question of which treatment to use.
“We found that among patients who were candidates for either partial or radical nephrectomy, the patients treated with partial nephrectomy seemed to have better survival long-term than patients treated with full nephrectomy,” said the study’s lead author, Hung-Jui Tan, MD, a urology resident at the University of Michigan where the research was done.
HUNG-JUI TAN, MD
Asked why earlier studies may have yielded contradictory evidence to these findings, Tan explained, “Our study is better representative of more contemporary surgical practice with updated techniques and more contemporary patients, where the earlier study was more representative of a historical experience.”
Patients in this study—who underwent treatment between 1992 and 2007—represent a cohort treated with more up-to-date surgical standards. Now, partial nephrectomy is more commonly considered for all kidney cancer patients, whereas in past practices partial nephrectomy was more often reserved for an unhealthy cohort of kidney cancer patients, those with chronic kidney disease, or those with a solitary kidney, Tan said. “It [the evidence] supports what the existing paradigm is in light of contradictory evidence that has recently come out.”
In this retrospective cohort study of 7,138 kidney cancer patients, 25 percent of those treated with partial nephrectomy had died after five years compared with 42 percent of those treated with full nephrectomy. To avoid the selection bias of earlier trials, the researchers limited patients in this study to include only those: who were candidates for either full or partial nephrectomy, who had early stage cancers (tumors 4 cm or smaller), who had localized disease, and who had no evidence of regional metastatic disease. Rates of cancer-specific mortality were statistically equivalent between the two patient groups—showing that patients in both groups were equally likely to die of kidney cancer, and that either procedure was equally likely to cure the cancer.
“Our findings suggest increasing use of partial nephrectomy would seem to improve patient outcomes long-term,” Tan said.
Improved survival rates among partial nephrectomy patients are likely because of the reduction in chronic kidney disease (linked to lipid disorders, cardiovascular disease, and renal failure), which is known to be associated with full kidney removal. But, Tan said additional studies are needed to confirm those assumptions.
Commenting on the study for this article, Walter Stadler, MD, explained the research is relevant because the pre-specified cohort included only patients with defined renal cancer, as opposed to other studies (that reached contradictory conclusions) that looked at patient cohorts with renal masses. He is the Fred C. Buffett Professor of Medicine and Director of the Genitourinary Program and Associate Dean for Clinical Research Hematology/Oncology Department at the University of Chicago Medical Center.
“This is the best epidemiologic and outcomes data that I’m aware of to support the survival benefit of partial nephrectomy in patients with small renal tumors,” Stadler said in an email interview.
But, he also notes full nephrectomies should not be ruled out as a treatment option for all kidney cancers. Technical challenges and surgery risk is higher in partial versus radical nephrectomies, and these barriers increase with tumor size, raising the question if partial kidney removal is still advantageous for larger tumors—and he suggests more research is needed to answer that question.
“This research is relevant for the smaller tumors (those less than 4 cm),” he said. “But, surgical expertise becomes a more important factor for such larger tumors.”
For more advanced cancer and other situations where tumor location may increase the risk of acute morbidity or complications, radical nephrectomy may be preferred, Tan explained. “Ultimately the decision between a partial nephrectomy and a radical nephrectomy is between the patient and the physician.”
“This study doesn’t say that everybody should get a partial nephrectomy, but it does say that for patients who would be candidates for both, the increased use of this surgery may improve rates of survival for patients with kidney cancer.”