Unilateral nephrectomy and cisplatin as risk factors of ifosfamide-induced nephrotoxicity: analysis of 120 patients.

PURPOSE: This study was performed to identify risk factors of ifosfamide-induced renal damage. PATIENTS AND METHODS: Renal function was assessed in 120 patients at a minimum of 3 months after completion of chemotherapy including ifosfamide. The cumulative ifosfamide dose ranged from 2 to 95 g/m2 (median, 30 g/m2). Ten patients had undergone unilateral nephrectomy; combination cytostatic treatment included cisplatin in 51 and methotrexate in 57. Sixty-eight patients had received gentamicin treatment. The glomerular filtration rate was estimated using the Schwartz formula. Proximal tubular function was assessed by the percent reabsorptions of glucose and 16 amino acids, the fractional excretion of sodium, and the fractional reabsorption of phosphate. In addition, the serum bicarbonate level was measured.
RESULTS: Proximal tubular dysfunction--with a predominance of renal amino acid (66.3%) and phosphate loss (38.3%)--was much more frequent than both glomerular impairment and acidosis. Seven patients were identified as having renal Fanconi's syndrome, and generalized tubulopathy was noted in another 15 patients. Ifosfamide-induced nephrotoxicity was dose-dependent, with a weak linear inverse correlation between cumulative ifosfamide dose and fractional phosphate reabsorption. Unilateral nephrectomy proved to be the single most important risk factor (odds ratio for the development of renal Fanconi's syndrome, 11.4), but cisplatin also significantly enhanced ifosfamide-mediated nephrotoxicity. Methotrexate, gentamicin, and patient age at primary diagnosis had no influence on renal function.
CONCLUSION: Ifosfamide chemotherapy should probably be restricted in patients after unilateral nephrectomy.