Partial nephrectomy is best option for small kidney tumors

May 1, 2010

Surgeons who automatically consider radical nephrectomy for small renal tumors are doing their patients a disservice. Data from Memorial Sloan-Kettering Cancer Center and other centers suggest that partial nephrectomy is more appropriate, especially for smaller tumors.

Key Points

San Francisco-Surgeons who automatically consider radical nephrectomy for small renal tumors are doing their patients a disservice.

"Partial nephrectomy preserves renal function and delays the onset of chronic kidney disease," Dr. Russo said. "Partial nephrectomy can be protective compared to radical nephrectomy because the glomerular filtration rate [GFR] is already depressed in many of our patients before surgery. The data show that we may be doing our patients a disservice by doing more aggressive surgery."

Imaging's role in surgical approach

The picture changed with the development of ultrasound, computed tomography, and magnetic resonance imaging. Incidental detection accounted for less than 5% of all kidney tumors before the widespread use of modern imaging, which is often used for the evaluation of non-specific abdominal or musculoskeletal complaints or in the management of unrelated cancer care.

Today, incidental detection is responsible for 70% of renal masses found, and the median tumor size is less than 4 cm. Performing radical nephrectomy today for such small renal tumors too often means destroying a significant portion of healthy, functional kidney tissue.

"Remember, 20% of tumors resected are actually benign and another 25% are indolent," Dr. Russo said. "If you cut out functional kidney tissue, you can send a patient into chronic kidney disease or renal failure."

Patients presenting with suspicious kidney masses are not comparable to kidney donors, he noted. The typical kidney tumor patient at MSKCC is 58 years old and has a GFR of 69 mL/min. That is more than a decade older than the typical carefully screened kidney donor, who has a GFR in the range of 90 to 100 mL/min range. A GFR of 60 mL/min or lower is consistent with chronic kidney disease.

About 26% of patients undergoing elective partial nephrectomy have an estimated GFR of less than 60 mL/min, typically due to common comorbidities such as hypertension, diabetes, and cigarette smoking. The loss of renal tissue not associated with a kidney tumor further decreases the renal functional reserve.

"Kidney tumor patients already have significant wear and tear on their kidneys," Dr. Russo said. "Partial nephrectomy preserves renal function and prevents or delays the onset of chronic kidney disease and the associated cardiovascular morbidity and potential mortality."

Surgery type does not affect survival

The type of nephrectomy does not affect survival. Data from MSKCC show no statistically significant difference in disease-free survival between patients undergoing a partial nephrectomy or radical nephrectomy for tumors less than 4 cm. Data from MSKCC and the Mayo Clinic, Rochester, MN, in patients with tumors between 4 cm and 7 cm also show no difference in overall survival or disease-free survival for partial versus radical nephrectomy.

Type of nephrectomy does affect kidney function. Patients undergoing radical nephrectomy are about 50% more likely to suffer chronic kidney disease than patients undergoing partial nephrectomy, Dr. Russo noted. A retrospective study using Surveillance, Epidemiology and End Results (SEER) and Medicare data found that patients who had a radical nephrectomy for small renal tumors were 1.4 times more likely to suffer a cardiovascular event and 1.38 times more likely to die during the 10 years following surgery compared to patients who had a partial nephrectomy.

Not surprisingly, SEER and Medicare data show a rising trend toward partial nephrectomies for renal tumors of 4 cm or less between 1996 and 2006. Nationwide, approximately 40% of patients with tumors less than 4 cm have a partial nephrectomy, but that percentage rises to 90% at MSKCC, Mayo Clinic, and other similar centers, Dr. Russo said.

Current practice at MSKCC calls for partial nephrectomy to be planned and attempted for all tumors less than 7 cm, including hilar and endophytic tumors. In addition, partial nephrectomy should be considered an option for larger tumors, particularly if they are polar and exophytic.

"It is very doable with standard techniques," Dr. Russo said. "In the end, leaving your patient with one-and-three-quarters kidneys versus just one kidney is worth the effort."