A patient diagnosed today with a small, localized kidney tumor is likely to receive the same treatment received by a similarly diagnosed patient in the 1960s -- the surgical removal of the entire affected kidney. This standard of care may change as the result of a recent study, led by Memorial Sloan-Kettering investigators, which found that removing the whole kidney leads to an increase in the risk of impaired function in the remaining kidney. The study revealed that when doctors remove only the tumor and a small portion of the surrounding tissue, patients are significantly less likely to experience chronic kidney disease.
Kidney Cancer Statistics
The American Cancer Society estimates that approximately 35,000 cases of kidney cancer will be diagnosed this year in the US. The study's researchers report that more than 60 percent of newly diagnosed kidney tumors are considered to be small sized, defined as four centimeters or less. These small renal cortical tumors -- which together account for the majority of all kidney tumors -- can be successfully treated with the less radical surgical procedure known as partial nephrectomy.
However, according to data from the Surveillance Epidemiology and End Results (SEER) registry, only 20 percent of all small renal cortical tumors were treated with partial nephrectomy since 2001. This means that 80 percent of patients with small tumors had their entire kidney removed, in what is known as a radical nephrectomy, leaving them with only one kidney and an increased risk of developing kidney disease. (Chronic kidney disease can lead to kidney failure, anemia, hypertension, and an increased risk of cardiovascular disease and death.)
Study Results
The retrospective study, published in the September 2006 issue of The Lancet Oncology [PubMed Abstract], tracked 662 patients with two healthy kidneys who received either a partial or a radical nephrectomy for a small, localized renal cortical tumor between 1989 and 2005. The investigators, led by senior author, Paul Russo, MD, a urologic surgeon at Memorial Sloan-Kettering, tested kidney function in each patient before and after surgery, using a highly sensitive test that measures what is known as the kidneys' estimated glomerular filtration rate.
Using this test, the researchers, who included colleagues from Tufts-New England Medical Center, found that approximately 25 percent of patients with small tumors had undetected pre-existing kidney disease before surgery -- leaving them dangerously susceptible, after surgery, to kidney failure. For those patients receiving the kidney-sparing partial nephrectomy, the study found an 80 percent probability of remaining free of chronic kidney disease three years after surgery. For those receiving the kidney-removing radical nephrectomy, the three-year probability of remaining free of chronic kidney disease dropped to 35 percent.
Analysis
Studies performed at Memorial Sloan-Kettering -- where more than 70 percent of all nephrectomies are of the organ-sparing partial variety -- and other institutions have demonstrated equal survival rates between partial and radical nephrectomy in patients with small tumors, with similar complications. As a result, the study's findings demonstrate the superiority of partial nephrectomy for the treatment of small tumors, as it provides effective tumor control, equivalent survival rates compared to radical nephrectomy, and a statistically lower risk of developing kidney disease and its complications.
"Based on our research findings, urological surgeons, when faced with a patient with a small renal mass, must now consider the long-term renal health of the patient on an equal par with providing local tumor control," says Dr. Russo. "Our study argues strongly for partial nephrectomy, whenever technically possible, as the most appropriate treatment for the patient with a small renal mass."
