Urine cytology in the detection of renal adenocarcinoma

Whereas urine cytology has proved to be of considerable diagnostic value for nonpapillary urothelial carcinoma, carcinoma in situ, and high-grade urothelial tumors, controversy has arisen over the accuracy of cytology in the diagnosis of renal neoplasms. To establish the reliability of urine cytology as a detection technique, 436 urine specimens from 59 patients with histologically proven renal adenocarcinoma were examined. Malignant cells in urinary sediment were found in 121 (27.75%) specimens from 31 (52.54%) patients. Seven of 20 (35%) patients with Stage I tumor showed neoplastic cells in 16 (16.5%) of 97 urinary samples. Positive cytologic features were found in 36.9% of 84 urinary specimens from 7 (50%) of 14 patients with tumors smaller than 5 cm. Using only imaging methods, the renal neoplasm was diagnosed in 58 (98.3%) cases. Urine cytology is, therefore, of little value in the diagnostic evaluation of known renal masses and in the detection of early-stage disease. In the current series there was not a single case with positive cytologic findings in which radiology did not reveal the tumor. The cytologic examination of the urinary sediment is unreliable in the diagnosis of radiologically unresolved cases of renal neoplasms. In 15 patients (44%) who had cancer cells in the urine the neoplasm had not invaded the renal pelvis. In 36% of patients with negative urine cytologic findings the renal pelvis was involved by renal adenocarcinoma. In the current study the desquamation of neoplastic cells in the urinary stream did not depend on tumor invasion of the renal pelvis. Based on the assumption that the primary objective of a screening procedure is to achieve an adequate sensitivity for early detection of disease, the results led the authors to conclude that the use of urine cytology as a possible screening test of renal adenocarcinoma is futile. Factors in the current study that diminished the practical value of cytologic examination of urinary sediment included the large number of specimens without malignant cells and the insensitivity of the procedure in diagnosing early renal adenocarcinoma of limited extent. Although this is the largest series reported, the number of cases considered was limited and further detailed studies are mandatory to definitively clarify the value of urine cytology in detecting renal adenocarcinoma.