Biopsy, Pathology Results Often Differ in UTUC

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Study results serve as a caution against relying on ureteroscopic biopsy to establish tumor grade and stage, researchers say.
Study results serve as a caution against relying on ureteroscopic biopsy to establish tumor grade and stage, researchers say.

Investigators have identified discrepancies between biopsy and final pathology results from upper tract urothelial carcinoma (UTUC) patients that, if confirmed, have important clinical consequences.

In a study published online in the Journal of Urology, Christopher B. Anderson, MD, MPH, of Columbia University in New York City, and colleagues reviewed the records of 314 patients with UTUC patients who underwent ureteroscopic biopsy followed by nephroureterectomy or segmental ureterectomy at 3 institutions during 2000 to 2016. Biopsy results indicated that 61% of patients had high-grade tumors (defined as grades 3 and 4) and 21% had subepithelial connective tissue invasion. Yet final pathology results revealed that higher proportions of patients than expected had high-grade tumors (79%) and stage T2 or higher disease (45%).

On multivariate analysis, 3 factors independently predicted higher-stage cancer: high-grade disease and subepithelial connective tissue invasion detected at biopsy, and older age. The 2 biopsy findings combined yielded a positive predictive value of 86% and a negative predictive value of 80% for muscle invasion.

The risk for upgrading was high. Among patients diagnosed with low-grade cancer on biopsy, 51% were upgraded at surgery. Having urine cytology that was positive for malignant cells increased the chances of upgrading, although not significantly.

According to the investigators, obtaining small biopsy fragments of 1 mm or less increased the likelihood that muscle-invasive disease would be missed.

“The predictive value of biopsy can likely be improved by more extensive ureteroscopic sampling, potentially aided by the use of baskets rather than forceps when possible,” Dr Anderson and his colleages stated. “This knowledge may improve risk stratification and help with selecting patients for more aggressive treatment.” They also recommended comparative studies on specific ureteroscopic instruments and techniques.

Reference

Margolin EJ, Matulay JT, Li G, et al. Discordance Between ureteroscopic biopsy and final pathology for upper tract urothelial carcinoma. J Urol. doi:10.1016/j.juro.2018.02.002

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