V1855: En-bloc resection of non-muscle invasive bladder tumors with a novel hybrid instrument (HybridKnife®)

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Introduction and Objectives
Bladder cancer represents the most frequent malignancy of the urinary tract. Global Cancer Statistics report a yearly incidence of 330,000 people diagnosed with bladder cancer and a total mortality of over 130,000 patients. Approximately 75-85 % of patients present with non-muscle invasive tumor stages. With conventional transurethral resection (TUR-BT) the oncological principle of en-bloc resection cannot be accomplished in the majority of bladder tumors. Due to limitations of the resection loop, the tumor can only be resected in several fractions, in a so-called piecemeal technique. The en-bloc resection of gastro-intestinal tumors, known as endoscopic submucosal dissection (ESD), is well established and has led to lower recurrence rates.

Methods
We used the combination instrument HybridKnife® (HK) for transurethral en-bloc resection (TUEB-RT) in analogy to ESD. The probe has a diameter of 7F and consists of a high-frequency electrode at the distal end whose hollow shaft is also used as a waterjet nozzle. The resection area was marked with punctiform coagulations and a water cushion was created underneath the tumor. The water cushion was created by the densely focused waterjet penetrating the bladder mucosa and forming a spacer in the subepithelial layer. Afterwards the mucosa was incised and the tumour undermined and excised. After extensive training with animal models we used this technique as a pilot study to determine patients` safety, technical feasibility and quality of pathological specimen. Complications were reported using the modified Clavien-Dindo classification.

Results
We performed TUEB-RT in 16 patients with the HK. 15 patients were solely operated with the HK, in 1 patient the procedure was finished using conventional TUR-BT. Mean resection time per lesion was 27 minutes (range 15-35 minutes). No major complications (>Clavien °II) nor a significant drop in hemoglobin (>1g/dl) was observed. Postoperative irrigation was stopped on the day of surgery in all patients. Pathology revealed 4 benign results, 3 Cis, 7 pTa, 2 pT1 and 1 pT2a tumors. Even in cases of accidental obturator stimulation handling was safely possible in all patients with a low risk of perforation.

Conclusions
TUEB-RT was feasible and reproducible in all cases. The technique is a promising attempt to implement oncological principles of tumor resection into endo-urological treatment of bladder tumors. A prospective randomized multicentre study to evaluate the applicability as well as the functional and oncological outcome was initiated in September 2012.

Funding: none