Urinary NMP22 and renal cell carcinoma

To demonstrate the incidence of positive urinary nuclear matrix protein 22 (NMP22) values associated with renal cell carcinoma (RCC) of the kidney. Currently, urinary NMP22 is used to detect recurrent transitional cell carcinoma of the bladder.

From May 1997 to March 1998, urinary NMP22 values were obtained from 65 patients who had undergone either computed tomography scanning of the abdomen or renal ultrasound. Of the 65, 32 presented with solid renal masses. These patients underwent radical or partial nephrectomy; subsequent pathologic examination revealed that 30 had RCC. Two patients had oncocytomas. The remaining 33 patients presented with blunt abdominal trauma or abdominal pain or for follow-up for a urologic problem (a kidney stone or benign renal cyst). These patients had no evidence of renal malignancy on imaging and were used as controls.

The urinary NMP22 values of patients with RCC were significantly higher than the values found in the control group (13.69 +/- 8.40 U/mL versus 3.03 +/- 2.70 U/mL, P <0.0078). Of the 30 patients with RCC, 12 (40%) had positive urinary NMP22 values of 10 U/mL or above. Chi-square analysis revealed a significant difference between the NMP22 values of the two groups (P <0.005). There were two false-positive NMP22 values in the 35 control patients.

Urinary NMP22 values used to detect transitional cell carcinoma in individuals with previously diagnosed bladder cancer should be more broadly evaluated, since elevations have also been found to occur in RCC of the kidney. This finding may result in an increase in the incidental discovery of RCC. Future, more specific, NMP assays may hold promise for the detection of RCC.