Prospective feasibility study of cryobiopsy in patients with suspected upper tract urothelial carcinoma

To evaluate the feasibility and specimen quality of cryobiopsy for ureterorenoscopic (URS) biopsy in suspected upper tract urothelial carcinoma (UTUC).

Using a newly developed flexible cryoprobe, a total of 80 biopsies were obtained in 10 consecutive patients with renal pelvis tumors suspicious for UTUC (cryobiopsy, n = 28; forceps, n = 28; basket, n = 24). The primary endpoint was the diagnostic yield of cryobiopsy; secondary endpoints included comparison with standard instruments, feasibility, safety, and specimen quality.

Cryobiopsy enabled a definitive histopathological diagnosis in all patients (primary endpoint). As a secondary endpoint, the percentage of diagnostic cryosamples was significantly higher than with conventional forceps (75.0% vs. 35.7%; p=0.007) or basket biopsy (29.2%; p=0.002). The proportion of representative samples was highest with cryobiopsy (82.1%) compared with forceps (46.4%, p = 0.011) and basket biopsy (54.2%, p = 0.038). Cryobiopsies were significantly larger (mean area 18.0 mm²) than forceps (6.4 mm², p<0.001) or basket specimens (9.6 mm², p=0.008). Histological assessability was highest with cryobiopsy (score 4.8 vs. 2.9 with forceps, p = 0.031, and 3.8 with basket, p > 0.999). Postoperative hematuria occurred in six of ten patients; it was managed conservatively, and no patient required transfusion or re-intervention.

Cryobiopsy in the renal pelvis is feasible and yielded larger, higher-quality specimens than standard instruments. Whether this improves staging, risk stratification, or treatment selection requires larger multicenter trials (trial registration number DRKS00025620).