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New onset of chronic kidney disease in patients with small renal cortical tumours undergoing radical or partial nephrectomy
The
clinical landscape concerning the management of small renal tumors
continues to change and now urologists must incorporate new and important
information as they plan operations. Today, 70% of renal masses are
detected incidentally when abdominal imaging is done for other reasons.
The median tumor size is approximately 4 cm, well within safe limits for
partial nephrectomy if technically feasible. It is now known that
approximately 20% of these masses are benign tumors including oncocytoma
and fat-poor angiomyolipoma, 25% are indolent tumors with limited
metastatic potential such as papillary and chromophobe carcinoma, and 54%
represent the more potentially malignant conventional clear cell carcinoma
that uncommonly achieves its metastatic potential when
4 cm or less. Accumulating clinical evidence indicates that partial
nephrectomy, first for tumors of 4 cm or less, and recently for
conventional clear cell tumors of up to 7 cm (1), provides equally
effective local tumor control as does radical nephrectomy withsurvival
rates of 90% or greater depending on the histological sub-type. Now
that survival is a strong probability for these patients, concerns for
their overall long term renal health have come into focus. Although
radical nephrectomy will not precipitate dialysis in the vast majority of
patients, chronic kidney disease has now emerged as an important concern.
This condition, defined as a glomerular filtration rate (GFR) of less than
60 ml/min/1.73m2, is now considered an
independent risk factor for the development of cardiovascular disease,
hospitalization, and death, the likelihood of which increases as the GFR
decreases (2). Using the MDRD equation to estimate GFR in a retrospective
cohort study of apparently well patients with a normal serum creatinine
and 2 kidneys, MSKCC investigators studied the impact of radical
nephrectomy (N=204) and partial nephrectomy (N=287) on GFR. To their
surprise, prior to operation, 171 patients (26%) had chronic kidney
disease with a GFR < 60ml/min/1.73m2. Following surgery, the 3-year
probability of freedom from new onset of GFR <60 ml/min/1.73 m2 was
80% in the PN group, compared to 35% in the RN group; and for new onset of
GFR <45, a level of severe chronic kidney disease, was 95 % in the PN
group, compared to 64% in the RN group (both p<0.0001).
On multivariable analysis, RN remained an independent and
significant risk factor for developing new onset of GFR <60 (hazard
ratio [HR] 3.82; 95%C.I. 2.75, 5.32;
p<0.0001) and GFR <45 ml/min/1.73m2
(HR 11.8, 95%C.I. 6.24, 22.4; p<0.0001) (3). Despite the strong case for partial nephrectomy as the major treatment for small renal tumors, evidence from the SEER and National Inpatient Sample databases indicates that across the United States more than 90% of patients with small renal tumors still undergo radical nephrectomy (4) Similar data from England and Canada has been generated. The overzealous use of radical nephrectomy for small renal tumors, by either open or laparoscopic techniques, must now be considered detrimental to the long term health and safety of the patient with a small renal cortical tumor. Widespread training in partial nephrectomy, either by open or laparoscopic approaches, is clearly indicated. The urologist facing a new patient visit with a small renal mass must pause to consider long term renal functional preservation, the initiation or worsening of preexisting chronic kidney disease and its subsequent cardiovascular risk enhancement on an equal par to local tumor control and rapid surgical convalescence when counselling their patient. A pre-surgical calculation of GFR estimate, patient age, tumor size, and the presence of significant medical co-morbidity, particularly in an elderly patient, can also make the strong case for active surveillance in selected patients.
Bibliographic reference:
1) Dash A., Vickers A.J., Schacter L.R. et al: Comparison of outcomes in elective partial vs. radical nephrectomy for clear cell renal cell carcinoma of 4-7 cm. BJU International 97:939-945, 2006. 2) Go, AS, Chertow GM, Fan D, McCulloch CE et al: Chronic kidney disease and the risks of death, cardiovascular events, and hospitalization. N. Eng. J. Med. 3511296, 2004.
Paul Russo Department of Urology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
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