Radical Nephrectomy for Kidney Cancer Linked to Lower Survival in Younger Patients

By Charles Bankhead
ROCHESTER, Minn., Jan. 9 -- Radical nephrectomy carried a twofold increase in mortality risk compared with partial nephrectomy in patients younger than 65 with small renal masses, investigators from the Mayo Clinic found.
In an analysis that included patients of all ages, however, radical nephrectomy was associated with a nonsignificant 12% increased risk compared with partial nephrectomy, R. Houston Thompson, M.D., and colleagues reported in the February issue of the Journal of Urology.
"For patients with small kidney tumors, removal of the entire kidney may be associated with long-term consequences that we did not previously recognize, compared with removal of just the tumor," said Dr. Thompson, now at Memorial Sloan-Kettering Cancer Center.
The authors of two accompanying commentaries warn against pointed out limitations of the study and warned against overinterpretation of the results.
"Recent evidence suggests that there is a graded impact on survival based on declining overall kidney function," Dr. Thompson said. "So as kidney function declines, the risk of heart attacks and heart-related events goes up, and consequently, the risk of death from these events goes up."
Recent studies have suggested that radical nephrectomy for renal tumors 4 cm or smaller significantly increases the risk of chronic renal failure compared with partial nephrectomy. Because renal failure is associated with cardiovascular morbidity and mortality, radical nephrectomy might decrease survival in patients with small renal tumors, the authors noted.
Numerous studies have demonstrated equivalent oncologic outcomes between the two procedures; however, data on overall survival have been lacking.
In an effort to clarify the association between surgical technique and overall survival, Dr. Thompson and colleagues analyzed data from the Mayo Clinic's nephrectomy registry. They limited the analysis to patients with sporadic, unilateral, solitary, and localized renal masses 4 cm or smaller treated by radical or partial nephrectomy from 1989 through 2003.
After exclusion of patients with only one kidney or impaired renal function, 648 patients were available for analysis. The primary endpoint was overall survival.
Radical nephrectomy was performed in 290 patients and partial nephrectomy in 358. At a median follow-up of 7.1 years, 502 patients remained alive.
In the overall analysis, radical nephrectomy did not increase all-cause mortality relative to partial nephrectomy (relative risk: 1.12, P=0.52). However, the analysis revealed a significant difference with patient age.
Stratification of the patient population at the median age of 65 resulted in 327 patients younger than the median. In that younger subgroup partial nephrectomy was associated with a relative risk of 2.16 (P=0.02) for death from any cause compared with partial nephrectomy.
The association remained significant after adjusting for year of surgery, preoperative creatinine, Charlson-Romano index, preoperative symptoms, diabetes, and tumor histology.
The data add to the debate about underuse of partial nephrectomy, the authors stated. Over the past decade many urologic surgeons have come to accept partial nephrectomy as the standard of care for small renal tumors. However, only 20% of renal tumors 2 to 4 cm are treated with partial nephrectomy in the U.S. and only 4% in England.
About two thirds of all renal masses are small and incidentally detected. With increasing experience, complications of partial nephrectomy have been minimized, they said.
"Thus, it remains perplexing why so few patients are treated with partial nephrectomy," the authors commented.
In an editorial that accompanied the report, Steven C. Campbell, M.D., of the Cleveland Clinic, cautioned against overinterpretation of the findings and overlooking the study's limitations.
Cause of death is not addressed, he said. And the major finding applied to a subgroup of patients, not the overall population.
"The exploration of enough subgroups increases the chances of a positive and potentially misleading finding," Dr. Campbell stated.
The study should be considered hypothesis generating, not definitive, he concluded.
In a second editorial commentary, Lee Richstone, M.D., and Louis R. Kavoussi, M.D., of North Shore Long Island-Jewish Health System in New Hyde Park, N.Y., pointed out that patients treated by radical nephrectomy were followed for 9.4 years versus 5.6 years for the partial nephrectomy group. That disparity alone might account for the observed difference.
Despite the limitations, the study generates a provocative question, wrote Drs. Richstone and Kavoussi: Does the additional nephron loss associated with radical nephrectomy result in increased mortality?
"This questions remains unanswered and we should await data … to determine the true impact of radical surgery on patient mortality," they concluded.
Neither the primary authors nor the editorialists disclosed potential conflicts.
Primary source: Journal of UrologySource reference:Thompson RH, et al "Radical nephrectomy for pT1a renal masses may be associated with decreased overall survival compared with partial nephrectomy" J Urol 2008; DOI:10.1016/j.juro.2007.09.077.