Urothelial carcinoma of the upper urinary tract: comparison between the WHO/ISUP 1998 consensus classification and WHO 1999 classification system.

OBJECTIVES: To compare the usefulness of World Health Organization (WHO)/International Society of Urological Pathologists 1998 consensus classification with the WHO 1999 classification in a large series of urothelial tumors of the upper urinary tract. Only a few bladder tumor studies have compared these systems.
METHODS: A clinical and histopathologic review was performed of all patients diagnosed in western Sweden between 1971 and 1998 with renal pelvic or ureteral carcinoma. We selected 555 surgically treated patients who all had a urothelial tumor on review of the pathologic findings and no bladder tumor before diagnosis of the upper tract tumor. The median follow-up was 52 months. Disease-specific survival was calculated using Kaplan-Meier estimates.
RESULTS: A total of 349 patients had Stage pTa, pT1, or pT2 tumor, with a 5-year disease-specific survival rate of 95%, 80%, and 79%, respectively. No significant difference was found in the prognosis among papillary urothelial neoplasm of low malignant potential and low-grade and high-grade tumors of the same stage. Nor was a difference found among papillary urothelial neoplasm of low malignant potential and grade 1, 2, and 3 tumors. Of the 349 patients, 171, all with high-grade Stage pT3 tumors, had a 35% disease-specific survival rate. Of these tumors, 38 were grade 2 and 133 were grade 3, with a survival rate of 49% and 25%, respectively (P <0.0037). All 35 pT4 tumors were high grade, and no patient survived past 30 months.
CONCLUSIONS: Tumor stage was a very strong predictor of prognosis in this series of patients treated with open surgery. The tumor grade had little additional prognostic value, although a small advantage was found for the WHO 1999 classification, but only for high-grade, Stage pT3 tumors.