Partial nephrectomy shows increased survival benefit

Washington-A recently published population-based study reinforces prior evidence from retrospective studies of the increased survival benefit of partial nephrectomy over radical nephrectomy, and suggests a cancer-specific survival benefit for nephron-sparing approaches as well.

“Our study does not rely on retrospective, high-volume, academic center data but rather reflects more patients in a population-based dataset and thus reflects actual community practice,” said lead author Keith J. Kowalczyk, MD, attending physician in the department of urology at MedStar Georgetown University Hospital, Washington.

According to Dr. Kowalczyk, the study data also suggest for the first time that nephron-sparing approaches may confer a cancer-specific survival.

The study, which was published online in BJU International (March 4, 2013), included 1,682 patients diagnosed with small renal masses between 2005 and 2007 identified using Surveillance, Epidemiology, and End Results-Medicare data. Patients included in the study were at least 66 years of age with a first and only cancer diagnosis of renal cell carcinoma and tumors less than ≤4 cm. Patients were treated with open radical nephrectomy (ORN, 404 patients), minimally invasive radical nephrectomy (MIRN, 535 patients), open partial nephrectomy (OPN, 330 patients), minimally invasive partial nephrectomy (MIPN,160 patients), ablation (211 patients), or surveillance (42 patients).

Using a logistic regression model to calculate propensity-adjusted outcomes, the study found significantly higher overall mortality rates for patients treated by ablation, MIRN, and ORN (19.6, 18.7, and 26.7 events per 100 person-years, respectively; p<.001).

Significantly higher cancer-specific mortality was associated with MIRN and ORN (3.4 and 4.7 events per 100 person-years, respectively; p<.001). Cancer-specific mortality for patients treated with ablation and MIPN was 0.0 events per 100 person-years (for both) and 0.6 for OPN.

Significant cost savings observed

The authors also examined the differences in cost among the different treatment approaches, and found significant cost savings with minimally invasive techniques (laparoscopic or robotic approaches).

Within 3 months of treatment, the costs of MIPN and MIRN ($15,695 and $15,373, respectively) were less than for OPN and ORN ($16,986 and $17,803). The lowest costs were for patients treated by surveillance and ablation ($2,911 and $10,720). Costs were determined by adding all Medicare health care expenditures within 3 months following treatment and subtracting expenditures in the 3 months prior to treatment.

“The cost outcomes show a real cost benefit for minimally invasive approaches, likely due to fewer postoperative complications, lower blood loss, and shorter hospital stays,” Dr. Kowalczyk said.

The study found significantly shorter lengths of hospital stay with minimally invasive approaches (p<.001). In addition, OPN and ORN were associated with significantly more overall complications (65.4% and 64.0%, respectively) than MIPN and MIRN (51.6% and 57.0%, p<.003), respiratory complications (28.8% and 25.1% vs. 18.3% and 20.3%, p<.003), and intensive care unit admissions (29.4% and 35.7% vs. 20.7% and 23.5%, p<.003).

Regardless of whether open or minimally invasive techniques were used, the study also found that the use of radical nephrectomy was associated with significantly more perioperative complications, perioperative acute renal failure, and hemodialysis (p<.001 for all), as well as the most frequent diagnosis of chronic renal insufficiency beyond the perioperative setting (p<.001). Patients treated with MIRN and ORN had significantly greater rates of diagnosis of new renal insufficiency (38.3 and 35.9 events per 100 person-years, respectively; p<.001).

Patients treated with partial nephrectomy, either MIPN or OPN, had significantly more urine leaks (p<.001).

“Given the overall survival benefit of partial nephrectomy by any means, we believe that partial nephrectomy should always be performed whenever possible,” said Dr. Kowalczyk. “If one is able to perform a laparoscopic or robotic partial nephrectomy, that is just icing on the cake in terms of cost savings.”

Several limitations of the study were noted, including its observational design, its use of Medicare data, short follow-up, and cost analysis restricted to only 3 months after surgery.UT