Benefits of partial vs. radical nephrectomy greater than expected

Treatment of small kidney tumors by partial nephrectomy leads to better outcomes, including a significantly lower mortality risk, compared with radical surgery, data on more than 7,000 procedures showed.

Partial nephrectomy was associated with a 46% reduction in the overall mortality hazard versus radical nephrectomy during 5 years of follow-up (HR: 0.54, 95% CI: 0.34-0.85).

“We were impressed by the size of the benefit, which is larger than had been suggested by clinical trial data and previous observational studies,” said first author Hung-Jui Tan, MD, a urology resident at the University of Michigan in Ann Arbor, working with David C. Miller, MD, and colleagues. “That being said, our study estimates the treatment effect among specific patients rather than the average over the whole cohort.”

Results of a recent European study showed a significant survival benefit in patients with small renal tumors treated by radical versus partial nephrectomy, reopening questions about the relative effectiveness of nephron-sparing surgery versus kidney removal (Eur Urol 2011; 59:e15-e26).

Dr. Tan and colleagues sought to clarify matters by means of an instrumental variable approach to balance measured and unmeasured covariates between patients treated by the two types of surgery.

Investigators reviewed the NCI Surveillance, Epidemiology, and End Results database to identify patients treated by radical or partial nephrectomy for clinical stage T1 kidney cancer from 1992 to 2007. They selected differential difference to a provider of partial nephrectomy as the instrumental variable.

The results showed 1,925 patients treated by partial nephrectomy and 5,213 by radical nephrectomy. During a median follow-up 5 years, 2,651 patients died, including 230 who died of kidney cancer. The overall reduction in the mortality hazard translated into a predicted survival advantage for partial nephrectomy of 6%, 12%, and 16% at 2, 5, and 8 years of follow-up (p

The magnitude of the survival benefit with partial nephrectomy increased to 58% for patients age ≤75 years and to 60% for patients with significant comorbid conditions. A trend toward better cancer-specific survival with partial nephrectomy did not achieve statistical significance. Cancer-specific survival did not differ between the groups.

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