Stesura Seveso Archivio Italiano di Urologia e Andrologia 2023; 95(4):11723 1 ORIGINAL PAPER the last 15 years (7, 8). The scoring system may be bene- ficial to in patients’ counselling about complexity of sur- gery and the anticipated success/ failure rate of PN. In daily practice, PN is attempted as the standard of care for small renal masses, regardless of the tumour’s complexity. The aim of this study is to look for the endophytic to total tumour volume ratio as an added variable to study the complexity of partial nephrectomy to patients with T1b/T2 renal tumours. METHODS Retrospective data collection for patients managed by par- tial nephrectomy, by a single surgeon (AK) for clinically T1b/T2 renal in 2018-2020. Radiologists were provided with the patients’ list for the aim of the study and calcu- lation of the tumour endophytic volume and the percent- age of the endophytic volume to the total volume was cal- culated. The whole tumor volume was calculated by using this equation: Antero-posterior x transverse x cran- iocaudal dimensions multiplied by 0.52. The area tool was then used to calculate the total tumor as well as to calculate the endophytic tumor component which lies within the kidney. The ratio endophytic to total tumor ratio was calculated by dividing the endophytic compo- nent to the whole tumor area. The endophytic compo- nent was identified by drawing a line through the tumour to complete the border of the kidney. Figure 1 illustrates the markings. Institutional ethical approval was obtained. Patients’ con- sent for publishing was obtained as well. Surgery was always started by full mobilization of the kid- ney and dissection of the renal pedicle regardless of the tumour location. Tumour was identified. Fat covering the tumour was left intact but margins of the tumour at con- tact with the kidney was cleared of fat. Fat in this region was always sent separately for pathological analysis. After tumour edges are all clearly seen, monopolar cautery was used on the renal capsule 5-10 mm beyond the tumour edge for marking without cutting deeply into the kidney parenchyma. After that, the vascular clamp was used over the artery and vein and deep cutting with the monopolar Introduction: Partial nephrectomy is the standard of care to patients with small renal masses. It is still encouraged to larger tumours whenever feasi- ble. The aim of this study is to look for the endophytic to total tumour volume ratio as an added variable to study the complex- ity of partial nephrectomy to patients with T1b/ T2 renal tumours. Methods: Retrospective data collection of patients that had par- tial nephrectomy for T1b/T2 renal tumours by a single surgeon was done. Radiological re-assessment for the CT images to measure the endophytic to total tumour volume ratio was done. Results: The mean age of the patients was 63 years. The study included 25 males and 11 females. All cases were managed by open surgery using retroperitoneal transverse lateral lumboto- my and warm ischemia was used in all patients. The mean tumour volume was 74 cc, the mean endophytic tumour volume was 29 cc. The mean percentage of endophytic to total tumour volume was 42%. Conclusions: Partial nephrectomy is safe for most of the patients with good performance status, having large renal masses. More complex surgery can be predicted in patients with endophytic to total tumour volume greater than 42%. KEY WORDS: RCC; Partial nephrectomy; Tumour volume. Submitted 6 September 2023; Accepted 28 September 2023 INTRODUCTION Partial nephrectomy (PN) is currently accepted as the stan- dard of care for most localized kidney cancer. The American society of clinical oncology defines partial nephrectomy as the standard of care for patients with T1a kidney mass (1). American Urology association guidelines (2021) confirm PN to be the preferred treatment for patients with T1a solid/complex cystic renal tumours (2). Canadian urology association guidelines recommend par- tial nephrectomy for treatment of tumours 2-4 cm in diam- eter (3). Most recent European guidelines (2022) (4) rec- ommend PN whenever feasible for T1 tumours, raising the bar to tumours up to 7 cm in diameter. Some studies did show the feasibility of PN for T2 renal tumours (5, 6). Renal scoring systems were emerged and validated over Endophytic to total tumour volume ratio: An added variable to patients with T1b/T2 renal tumours undergoing partial nephrectomy Asmaa Ismail 1, Vahid Mehrnoush 1, Amer Alaref 2, Radu Rozenberg 2, Hazem Elmansy 1, Walid Shahrour 1, Nishigandha Burute 2, Anatoly Shuster 2, Owen Prowse 1, Ahmed Zakaria 1, Walid Shabana 1, Ahmed Kotb 1 1 Urology Department, TBRHSC, Northern Ontario School of Medicine University, Thunder Bay, ON, Canada; 2 Radiology Department, TBRHSC, Northern Ontario School of Medicine University, Thunder Bay, ON, Canada. DOI: 10.4081/aiua.2023.11723 Summary Archivio Italiano di Urologia e Andrologia 2023; 95(4):11723 A. Ismail, V. Mehrnoush, A. Alaref, et al. 2 cautery mixed with mobilizing the wedge having the tumour away with an empty blade handle till tumour with normal parenchymal margin was completely removed. We repair collecting system if encountered. We then use the monopolar cautery spray to cauterize the parenchymal edges before repair. Vicryl 0 was then used to take multiple deep interrupted transverse mattress sutures. Once satisfied, the whole sutures are tied and the vascular clamp is removed. We usually cover the renor- rhaphy with a large piece of surgicel leave a drain for 48 hours. The patient was usually discharged on the morn- ing of the third postoperative day. RESULTS Thirty-six patients were identified fulfilling our criteria. The mean age of the patients was 63 years. The study included 25 males and 11 females. All cases were man- aged by open surgery using retroperitoneal transverse lat- eral lumbotomy (9). Warm ischemia was applied to all cases, clamping both the renal artery and the vein. The mean ischemic time was 9 minutes. No case required intra or postoperative blood transfusion. No case was changed to radical nephrectomy. Thirty-two cases had solid tumour and 4 had Bosniak 3/4 renal cysts. The mean tumour diameter was 5.5 cm, rang- ing from 4.2 to 10 cm. The mean tumour volume was 74 cc, the mean endophytic tumour volume was 29 cc. The mean percentage of endophytic to total tumour volume was 42%. Endophytic to total tumour volume of > 42% was found to be associated with longer mean operative time (90 minutes versus 50 minutes. P 0.01) and more mean blood loss (200 versus 50 ml. P 0.02). Renal cell carcinoma (RCC) was the pathological diagnosis of all patients, but one case had angiomyolipoma (AML). Fortunately, positive surgical margin was only seen in the patient having AML. Pathological T3 was identified in 5 patients. Over a median follow up of 3 years, disease and recurrence free survival was 100%. Figure 2 shows a case with a tumour diameter of 4.2 cm involving the right lower renal pole. The endophytic to total tumour volume was 39%. The case was successfully managed by PN, under warm ischemic time of 10 min- utes. Single patient had significant hematuria and drop in Hgb few weeks after surgery. Pseudoaneurysm was iden- tified and clamping by the interventional radiology team was safely done. That patient had endophytic to total tumour volume of 79%. DISCUSSION In patients with adequate performance status, PN should be always attempted. All guidelines agree on that for T1a tumours, and some guidelines and many publications extend the recommendation to T1b/ T2 tumours. Scoring systems were introduced and validated to help the deci- sion making and patients’ counselling. Efforts were ongoing to identify adding parameters to predict the success of PN. Sciorio et al. (2020) identified MIC (surgical margin, ischemic time, and complications) as a parameter that could mark the success of the surgery. In their study. Low MIC was correlated to high PADUA score and large tumour diameter (10). Tumour volume and specifically the endophytic tumour volume was not widely studied. Tiwari et al. (11) studied 87 patients that underwent PN for T1a renal mass and found a positive correlation between the endophytic tumour volume and nephrometry score. Mohammadi et al. (12) published a case report for a suc- cessful PN to 17 cm renal mass. While they did not meas- ure the tumour volume in their study, the CT images they published clearly showed very low ratio of endophytic to total tumour volume. To our knowledge, this is the first study looking for the percentage of endophytic to total tumour volume in patients that underwent PN for T1b/T2 renal masses. In our hands, PN was safe for such large renal tumours in Figure 1. Calculation of the tumour endophytic volume and the percentage of the endophytic volume to the total volume. The endophytic component was identified by drawing a line through the tumour to complete the border of the kidney. Figure 2. Figure shows a case with a tumour diameter of 4.2 cm involving the right lower renal pole. The endophytic to total tumour volume was 39%. Archivio Italiano di Urologia e Andrologia 2023; 95(4):11723 3 Endophytic to total tumour volume ratio medically fit patients. We must disclose that this study did not include patients with similar or smaller tumour mass that we elected to do radical nephrectomy because of their poor performance status that we felt PN may be an added risk to them. In our experience, the patients’ performance status and comorbidities were the main fac- tors we consider when offering partial versus radical nephrectomy. While all cases that had PN for large renal masses were successful, cases that had larger endophytic to total tumour volume had significantly longer operative time and blood loss. CONCLUSIONS Partial nephrectomy is a safe treatment option that should be attempted in most of the patients with good perform- ance status regardless of the tumour size. Endophytic to total tumour volume is an added parameter to consider for surgical planning. Endophytic to total tumour volume ratio of greater than 0.42 was associated with longer oper- ative time and more blood loss in patients with T1b/T2 tumours undergoing partial nephrectomy. REFERENCES 1. Finelli A, Ismaila N, Bro B, et al. Management of Small Renal Masses: American Society of Clinical Oncology Clinical Practice Guideline. J Clin Oncol. 2017; 35:668-680. 2. Campbell SC, Clark PE, Chang SS, et al. Renal Mass and Localized Renal Cancer: Evaluation, Management, and Follow-Up: AUA Guideline: Part I. J Urol. 2021; 206:199-208. 3. Richard PO, Violette PD, Bhindi B, et al. Canadian Urological Association guideline: Management of small renal masses - Full-text. Can Urol Assoc J. 2022; 16:E61-E75. 4. Ljungberg B, Albiges L, Abu-Ghanem Y, et al. European Association of Urology Guidelines on Renal Cell Carcinoma: The 2022 Update. Eur Urol. 2022; 82:399-410. 5. Nahar B, Gonzalgo ML. What is the current role of partial nephrectomy for T2 tumors? Can J Urol. 2017; 24:8698-8704. 6. 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Role of computed tomogra- phy-calculated intraparenchymal tumor volume in assessment of patients undergoing partial nephrectomy. Int J Urol. 2018; 25:436- 441. 12. Mohammadi A, Aghamir SMK. Partial nephrectomy of a huge solid-cystic renal mass with final pathology of renal cell carcinoma. J Surg Case Rep. 2022; 2022:rjab622. Correspondence Asmaa Ismail, MD asmaaismail0782@gmail.com Vahid Mehrnoush, MD vahidmehrnoush7@gmail.com Hazem Elmansy, MD hazem.mansy@rocketmail.com Walid Shahrour, MD Walid.shahrour@gmail.com Owen Prowse, MD owen.prowse@tbh.net Ahmed Zakaria, MD aszakaria81@yahoo.com Walid Shabana, MD Waleed.shabana@gmail.com Ahmed Kotb, MD, FRCSC, FRCS Urol, FEBU (Corresponding Author) Associate Professor drahmedfali@gmail.com Urology Department, TBRHSC, Northern Ontario School of Medicine University - 980 Oliver Road, Thunder Bay, ON, Canada. P7B 6V4 Amer Alaref, MD Amer.Alaref@tbh.net Radu Rozenberg, MD Radu.Rozenberg@tbh.net Nishigandha Burute, MD nishirad@gmail.com Anatoly Shuster, MD shustera@tbh.net Radiology Department, TBRHSC, Northern Ontario School of Medicine University, Thunder Bay, ON, Canada Conflict of interest: The authors declare no potential conflict of interest.