Reply to Mattias Hoglund's Letter to the Editor re: Alexander Cox, Niklas Klumper, Johannes Stein, et al. Molecular Urothelial Tumor Cell Subtypes Remain Stable During Metastatic Evolution. Eur Urol. In press. https://doi.org/10.1016/j.eururo.2023.03.020

Multiport robotic surgery in the retroperitoneum is limited by the bulky robotic frame and clashing of instruments. Moreover, patients are placed in the lateral decubitus position, which has been linked to complications.To assess the feasibility and safety of a supine anterior retroperitoneal access (SARA) technique with the da Vinci Single-Port (SP) robotic platform.Between October 2022 and January 2023, 18 patients underwent surgery using the SARA technique for renal cancer, urothelial cancer, or ureteral stenosis. Perioperative variables were prospectively collected and outcomes were assessed.With the patient in a supine position, a 3-cm incision is made at the McBurney point and the abdominal muscles are dissected. Finger dissection is used to develop the retroperitoneal space for the da Vinci SP access port. After docking, the first step is to dissect retroperitoneal tissue to reveal the psoas muscle. This allows identification of the ureter, the inferior renal pole, and the hilum.A descriptive statistical analysis was performed. Data collected included demographics, operative time, warm ischemia time (WIT), surgical margin status, complications, length of hospital stay, 30-d Clavien-Dindo complications, and postoperative narcotic use.Twelve patients underwent partial nephrectomy (PN) and two each underwent pyeloplasty, radical nephroureterectomy, and radical nephrectomy. In the PN group, mean age was 57 yr (interquartile range [IQR] 30–73), median body mass index was 32 kg/m2 (IQR 17–58), and 25% had stage ≥3 chronic kidney disease. The median Charlson comorbidity index was 3 (IQR 0–7) and 75% of PN patients had an American Society of Anesthesiologists score ≥3. The median RENAL score was 5 (IQR 4–7). The median WIT was 25 min (IQR 16–48) and the median tumor size was 35 mm (IQR 16–50). The median estimated blood loss was 105 ml (IQR 20–400) and the median operative time was 160 min (IQR 110–200). Positive surgical margins were found in one patient. In the overall cohort, one patient was readmitted and managed conservatively; 83% of the PN group were discharged on the same day as their surgery, with the remainder discharged the next day. At 7 d after surgery, no patients reported narcotic use.The SARA approach is feasible and safe. Larger studies are needed to confirm this approach as a one-step solution for upper urinary tract surgery.We assessed initial outcomes of a novel approach for accessing the retroperitoneum (the space behind the abdominal cavity and in front of the back muscles and spine) during robot-assisted surgery in the upper urinary tract. The patient is placed on their back and surgery is performed with a single-port robot. Our results show that this approach was feasible and safe, with low complication rates, less postoperative pain, and earlier discharge. This is a promising start, but larger studies are needed to confirm our findings.