Dynamic regulation of hypoxia-inducible factor-1α activity is essential for normal B cell development.

B lymphocyte development and selection are central to adaptive immunity and self-tolerance. These processes require B cell receptor (BCR) signaling and occur in bone marrow, an environment with variable hypoxia, but whether hypoxia-inducible factor (HIF) is involved is unknown. We show that HIF activity is high in human and murine bone marrow pro-B and pre-B cells and decreases at the immature B cell stage. This stage-specific HIF suppression is required for normal B cell development because genetic activation of HIF-1α in murine B cells led to reduced repertoire diversity, decreased BCR editing and developmental arrest of immature B cells, resulting in reduced peripheral B cell numbers. HIF-1α activation lowered surface BCR, CD19 and B cell-activating factor receptor and increased expression of proapoptotic BIM. BIM deletion rescued the developmental block. Administration of a HIF activator in clinical use markedly reduced bone marrow and transitional B cells, which has therapeutic implications. Together, our work demonstrates that dynamic regulation of HIF-1α is essential for normal B cell development.

Fumarate induces vesicular release of mtDNA to drive innate immunity.

Mutations in fumarate hydratase (FH) cause hereditary leiomyomatosis and renal cell carcinoma1. Loss of FH in the kidney elicits several oncogenic signalling cascades through the accumulation of the oncometabolite fumarate2. However, although the long-term consequences of FH loss have been described, the acute response has not so far been investigated. Here we generated an inducible mouse model to study the chronology of FH loss in the kidney. We show that loss of FH leads to early alterations of mitochondrial morphology and the release of mitochondrial DNA (mtDNA) into the cytosol, where it triggers the activation of the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING)-TANK-binding kinase 1 (TBK1) pathway and stimulates an inflammatory response that is also partially dependent on retinoic-acid-inducible gene I (RIG-I). Mechanistically, we show that this phenotype is mediated by fumarate and occurs selectively through mitochondrial-derived vesicles in a manner that depends on sorting nexin 9 (SNX9). These results reveal that increased levels of intracellular fumarate induce a remodelling of the mitochondrial network and the generation of mitochondrial-derived vesicles, which allows the release of mtDNAin the cytosol and subsequent activation of the innate immune response.

Not-so-simple nephrectomy: Comparative analysis of radical and simple nephrectomy in a high-volume tertiary referral center.

OBJECTIVES: Simple nephrectomies can be challenging with significant morbidity. To prove the hypothesis of "not-so-simple" nephrectomy, we compared demographics, perioperative outcomes, and complications between simple and radical nephrectomy in a tertiary referral center. METHODS: We analyzed 473 consecutive radical nephrectomies (January 2018-October 2020) and simple nephrectomies (January 2016-October 2020). Univariate and multivariate analysis of perioperative outcomes utilized the Mann-Whitney U test, Chi-squared test, Mantel-Haenszel test of trend, and multiple linear regression. Radical nephrectomies were classified in cT1, cT2a, and cT2b-T3 subgroups and compared to simple nephrectomies. Minimally invasive and open techniques were compared between the two groups. Infected versus non-infected simple nephrectomies were compared. RESULTS: A total of 344 radical and 129 simple nephrectomies were included. Simple nephrectomy was an independent predictor of increased operative time (p = 0.001), length of stay (p = 0.049), and postoperative complications (p < 0.001). Simple nephrectomies had higher operative time (p < 0.001), length of stay (p = 0.014), and postoperative morbidity (p < 0.001) than cT1 radical nephrectomies and significantly more Clavien 1-2 complications than cT2a radical nephrectomies (p = 0.001). The trend was similar in minimally invasive operations. However, conversion to open rates was not significantly different. Infected simple nephrectomies had increased operative time (p < 0.001), length of stay (p = 0.005), blood loss (p = 0.016), and intensive care stay (p = 0.019). CONCLUSIONS: Patients undergoing simple nephrectomy experienced increased operative time and morbidity. Simple nephrectomy carries higher morbidity than radical nephrectomy in tumors ≤10 cm. Robotic simple nephrectomies may reduce open conversion rates. Postoperative intensive care and enhanced recovery may be essential in simple nephrectomy planning with infected pathology.

Diagnosis, treatment, and survival from kidney cancer: real-world National Health Service England data between 2013 and 2019.

OBJECTIVES: To report the NHS Digital (NHSD) data for patients diagnosed with kidney cancer (KC) in England. We explore the incidence, route to diagnosis (RTD), treatment, and survival patterns from 2013 to 2019. MATERIALS AND METHODS: Data was extracted from the Cancer Data NHSD portal for International Classification of Diseases, 10th edition coded KC; this included Cancer Registry data, Hospital Episode Statistics, and cancer waiting times data. RESULTS: Registrations included 66 696 individuals with KC. Incidence of new KC diagnoses increased (8998 in 2013, to 10 232 in 2019), but the age-standardised rates were stable (18.7-19.4/100 000 population). Almost half of patients (30 340 [45.5%]) were aged 0-70 years and the cohort were most frequently diagnosed with Stage 1-2 KC (n = 26 297 [39.4%]). Most patients were diagnosed through non-urgent general practitioner referrals (n = 16 814 [30.4%]), followed by 2-week-wait (n = 15 472 [28.0%]) and emergency routes (n = 11 796 [21.3%]), with older patients (aged ≥70 years), Stage 4 KCs, and patients with non-specified renal cell carcinoma being significantly more likely to present through the emergency route (all P < 0.001). Invasive treatment (surgery or ablation), radiotherapy, or systemic anti-cancer therapy use varied with disease stage, patient factors, and treatment network (Cancer Alliance). Survival outcomes differed by Stage, histological subtype, and social deprivation class (P < 0.001). Age-standardised mortality rates did not change over the study duration, although immunotherapy usage is likely not captured in this study timeline. CONCLUSION: The NHSD resource provides useful insight about the incidence, diagnostic pathways, treatment, and survival of patients with KC in England and a useful benchmark for the upcoming commissioned National Kidney Cancer Audit. The RTD data may be limited by incidental diagnoses, which could confound the high proportion of 'emergency' diagnoses. Importantly, survival outcomes remained relatively unchanged.

Fumarate is an epigenetic modifier that elicits epithelial-to-mesenchymal transition.

Mutations of the tricarboxylic acid cycle enzyme fumarate hydratase cause hereditary leiomyomatosis and renal cell cancer. Fumarate hydratase-deficient renal cancers are highly aggressive and metastasize even when small, leading to a very poor clinical outcome. Fumarate, a small molecule metabolite that accumulates in fumarate hydratase-deficient cells, plays a key role in cell transformation, making it a bona fide oncometabolite. Fumarate has been shown to inhibit α-ketoglutarate-dependent dioxygenases that are involved in DNA and histone demethylation. However, the link between fumarate accumulation, epigenetic changes, and tumorigenesis is unclear. Here we show that loss of fumarate hydratase and the subsequent accumulation of fumarate in mouse and human cells elicits an epithelial-to-mesenchymal-transition (EMT), a phenotypic switch associated with cancer initiation, invasion, and metastasis. We demonstrate that fumarate inhibits Tet-mediated demethylation of a regulatory region of the antimetastatic miRNA cluster mir-200ba429, leading to the expression of EMT-related transcription factors and enhanced migratory properties. These epigenetic and phenotypic changes are recapitulated by the incubation of fumarate hydratase-proficient cells with cell-permeable fumarate. Loss of fumarate hydratase is associated with suppression of miR-200 and the EMT signature in renal cancer and is associated with poor clinical outcome. These results imply that loss of fumarate hydratase and fumarate accumulation contribute to the aggressive features of fumarate hydratase-deficient tumours.

Growth and renal function dynamics of renal oncocytomas in patients on active surveillance.

OBJECTIVES: To study the natural history of renal oncocytomas and address indications for intervention by determining how growth is associated with renal function over time, the reasons for surgery and ablation, and disease-specific survival. PATIENTS AND METHODS: The study was conducted in a retrospective cohort of consecutive patients with renal oncocytoma on active surveillance reviewed at the Specialist Centre for Kidney Cancer at the Royal Free London NHS Foundation Trust (2012 to 2019). Comparison between groups was performed using Mann-Whitney U-tests and chi-squared tests. A mixed-effects model with a random intercept for patient was used to study the longitudinal association between tumour size and estimated glomerular filtration rate (eGFR). RESULTS: Longitudinal data from 98 patients with 101 lesions were analysed. Most patients were men (68.3%) and the median (interquartile range [IQR]) age was 69 (13) years. The median (IQR) follow-up was 29 (26) months. Most lesions were small renal masses, and 24% measured over 4 cm. Over half (64.4%) grew at a median (IQR) rate of 2 (4) mm per year. No association was observed between tumour size and eGFR over time (P = 0.871). Nine lesions (8.9%) were subsequently treated. Two deaths were reported, neither were related to the diagnosis of renal oncocytoma. CONCLUSION: Natural history data from the largest active surveillance cohort of renal oncocytomas to date show that renal function does not seem to be negatively impacted by growing oncocytomas, and confirms clinical outcomes are excellent after a median follow-up of over 2 years. Active surveillance should be considered the 'gold standard' management of renal oncocytomas up to 7cm.

Impact of the first surge of the COVID-19 pandemic on a tertiary referral centre for kidney cancer.

OBJECTIVE: To analyse the impact of the COVID-19 pandemic on a centralized specialist kidney cancer care pathway. MATERIALS AND METHODS: We conducted a retrospective analysis of patient and pathway characteristics including prioritization strategies at the Specialist Centre for Kidney Cancer located at the Royal Free London NHS Foundation Trust (RFH) before and during the surge of COVID-19. RESULTS: On 18 March 2020 all elective surgery was halted at RFH to redeploy resources and staff for the COVID-19 surge. Prioritizing of patients according to European Association of Urology guidance was introduced. Clinics and the specialist multidisciplinary team (SMDT) meetings were maintained with physical distancing, kidney surgery was moved to a COVID-protected site, and infection prevention measurements were enforced. During the 7 weeks of lockdown (23 March to 10 May 2020), 234 cases were discussed at the SMDT meetings, 53% compared to the 446 cases discussed in the 7 weeks pre-lockdown. The reduction in referrals was more pronounced for small and asymptomatic renal masses. Of 62 low-priority cancer patients, 27 (43.5%) were deferred. Only one (4%) COVID-19 infection occurred postoperatively, and the patient made a full recovery. No increase in clinical or pathological upstaging could be detected in patients who underwent deferred surgery compared to pre-COVID practice. CONCLUSION: The first surge of the COVID-19 pandemic severely impacted diagnosis, referral and treatment of kidney cancer at a tertiary referral centre. With a policy of prioritization and COVID-protected pathways, capacity for time-sensitive oncological interventions was maintained and no immediate clinical harm was observed.

Radiomics to better characterize small renal masses.

PURPOSE: Radiomics is a specific field of medical research that uses programmable recognition tools to extract objective information from standard images to combine with clinical data, with the aim of improving diagnostic, prognostic, and predictive accuracy beyond standard visual interpretation. We performed a narrative review of radiomic applications that may support improved characterization of small renal masses (SRM). The main focus of the review was to identify and discuss methods which may accurately differentiate benign from malignant renal masses, specifically between renal cell carcinoma (RCC) subtypes and from angiomyolipoma without visible fat (fat-poor AML) and oncocytoma. Furthermore, prediction of grade, sarcomatoid features, and gene mutations would be of importance in terms of potential clinical utility in prognostic stratification and selecting personalised patient management strategies. METHODS: A detailed search of original articles was performed using the PubMed-MEDLINE database until 20 September 2020 to identify the English literature relevant to radiomics applications in renal tumour assessment. In total, 42 articles were included in the analysis in 3 main categories related to SRM: prediction of benign versus malignant SRM, subtypes, and nuclear grade, and other features of aggressiveness. CONCLUSION: Overall, studies reported the superiority of radiomics over expert radiological assessment, but were mainly of retrospective design and therefore of low-quality evidence. However, it is clear that radiomics is an attractive modality that has the potential to improve the non-invasive diagnostic accuracy of SRM imaging and prediction of its natural behaviour. Further prospective validation studies of radiomics are needed to augment management algorithms of SRM.

Pattern, timing and predictors of recurrence after surgical resection of chromophobe renal cell carcinoma.

PURPOSE: Currently there are no specific guidelines for the post-operative follow-up of chromophobe renal cell carcinoma (chRCC). We aimed to evaluate the pattern, location and timing of recurrence after surgery for non-metastatic chRCC and establish predictors of recurrence and cancer-specific death. METHODS: Retrospective analysis of consecutive surgically treated non-metastatic chRCC cases from the Royal Free London NHS Foundation Trust (UK, 2015-2019) and the international collaborative database RECUR (15 institutes, 2006-2011). Kaplan-Meier curves were plotted. The association between variables of interest and outcomes were analysed using univariate and multivariate Cox proportional hazards regression models with shared frailty for data source. RESULTS: 295 patients were identified. Median follow-up was 58 months. The five and ten-year recurrence-free survival rates were 94.3% and 89.2%. Seventeen patients (5.7%) developed recurrent disease, 13 (76.5%) with distant metastases. 54% of metastatic disease diagnoses involved a single organ, most commonly the bone. Early recurrence (< 24 months) was observed in 8 cases, all staged ≥ pT2b. 30 deaths occurred, of which 11 were attributed to chRCC. Sarcomatoid differentiation was rare (n = 4) but associated with recurrence and cancer-specific death on univariate analysis. On multivariate analysis, UICC/AJCC T-stage ≥ pT2b, presence of coagulative necrosis, and positive surgical margins were predictors of recurrence and cancer-specific death. CONCLUSION: Recurrence and death after surgically resected chRCC are rare. For completely excised lesions ≤ pT2a without coagulative necrosis or sarcomatoid features, prognosis is excellent. These patients should be reassured and follow-up intensity curtailed.

Independence of HIF1a and androgen signaling pathways in prostate cancer.

BACKGROUND: Therapeutic targeting of the androgen signaling pathway is a mainstay treatment for prostate cancer. Although initially effective, resistance to androgen targeted therapies develops followed by disease progression to castrate-resistant prostate cancer (CRPC). Hypoxia and HIF1a have been implicated in the development of resistance to androgen targeted therapies and progression to CRCP. The interplay between the androgen and hypoxia/HIF1a signaling axes was investigated. METHODS: In vitro stable expression of HIF1a was established in the LNCaP cell line by physiological induction or retroviral transduction. Tumor xenografts with stable expression of HIF1a were established in castrated and non-castrated mouse models. Gene expression analysis identified transcriptional changes in response to androgen treatment, hypoxia and HIF1a. The binding sites of the AR and HIF transcription factors were identified using ChIP-seq. RESULTS: Androgen and HIF1a signaling promoted proliferation in vitro and enhanced tumor growth in vivo. The stable expression of HIF1a in vivo restored tumor growth in the absence of endogenous androgens. Hypoxia reduced AR binding sites whereas HIF binding sites were increased with androgen treatment under hypoxia. Gene expression analysis identified seven genes that were upregulated both by AR and HIF1a, of which six were prognostic. CONCLUSIONS: The oncogenic AR, hypoxia and HIF1a pathways support prostate cancer development through independent signaling pathways and transcriptomic profiles. AR and hypoxia/HIF1a signaling pathways independently promote prostate cancer progression and therapeutic targeting of both pathways simultaneously is warranted.

Safety and feasibility of early single-dose mitomycin C bladder instillation after robot-assisted radical nephroureterectomy.

OBJECTIVES: To assess the safety and feasibility of early single-dose mitomycin C (MMC) bladder instillation after robot-assisted radical nephroureterectomy (RARNU) at a tertiary kidney cancer centre. RARNU with bladder cuff excision and subsequent MMC bladder instillation to reduce recurrence risk is the 'gold standard' for high-risk upper urinary tract urothelial carcinoma (UUTUC). We adapted a RARNU technique with precise distal ureteric dissection, bladder cuff excision and watertight bladder closure. PATIENTS AND METHODS: We retrospectively reviewed all patients undergoing RARNU for UUTUC at our centre performed as a standardised transperitoneal procedure comprising of: bladder cuff excision, two-layer watertight closure and intraoperative bladder leak test; without re-docking/re-positioning of the robotic surgical system. Patient demographics, the timing of MMC instillation, adverse events (surgical and potentially MMC-related) and length of stay (LOS) were assessed according to the Clavien-Dindo classification. RESULTS: A total of 69 patients underwent a RARNU with instillation of MMC. The median (interquartile range [IQR]) age was 70 (62-78) years. The median (IQR) day of MMC instillation was 2 (1-3) days and the median (IQR) LOS was 2 (2-4) days, with urethral catheter removal on day of discharge in all cases. Only Grade I Clavien-Dindo complications occurred in seven patients (10%); five had ileus, one a wound infection and one a self-limiting delirium, all managed conservatively. No adverse events potentially related to MMC instillation were noted within 30 days postoperatively. CONCLUSION: The use of intravesical MMC instillation given in the immediate postoperative period appears feasible and safe in patients undergoing RARNU with intraoperative confirmation of a water-tight closure ensuring early catheter-free discharge, with no significant adverse events. The potential reduction in intravesical recurrence in patients receiving early MMC needs to be assessed with longitudinal follow-up studies.

Qualitative exploration of the renal stone patients' experience and development of the renal stone-specific patient-reported outcome measure.

OBJECTIVES: To investigate the experience of patients living with renal calculi via a qualitative methodology, aiming to develop and validate a disease-specific patient-reported outcome measure (PROM) for renal stones, the Cambridge Renal Stone PROM (CReSP). PATIENTS, SUBJECTS AND METHODS: Patients with radiologically confirmed renal calculi who had undergone a range of management options were invited to focus groups or semi-structured interviews to elicit patient input and generate the PROM content. The developed renal stone PROM underwent validity studies included Cronbach's α for internal consistency, Spearman's and Pearson's correlation coefficients for test-retest reliability. Discriminant validity was assessed by Pearson's correlation coefficients vs the EuroQol five-dimensional five-level questionnaire (EQ-5D-5L). Our project has Health and Social Care Research Ethics Committee approval. RESULTS: A total of 106 subjects participated in creating the newly developed PROM. In all, 36 patients were invited to 22 semi-structured interviews and four focus groups, until reaching saturation. Major issues reported, and themes selected for the renal stone PROM included pain, anxiety, limitations to social life and tiredness, urinary symptoms, dietary changes' impacts, and gastrointestinal tract symptoms. Reliability analysis for 30 patients to determine internal consistency using Cronbach's α with a mean (range) of 0.91 (0.90-0.93) within domains and Cronbach's α between domains was 0.92. Average inter-item Pearson's and Spearman's correlation within domains was performed, with a Pearson's correlation mean (range) of 0.77 (0.73-0.85) and Spearman's correlation mean (range) of 0.72 (0.63-0.77). The test-retest Pearson's correlation mean (range) was 0.85 (0.57-0.95). Validity assessment was performed for 20 patients vs 20 controls. Pearson's correlation with EQ-5D-5L was -0.74, showing the newly developed PROM successfully discriminated patients with kidney stones. Our final renal stone PROM consists of 14 questions that are rated on a Likert scale; the higher the score, the worse the effect on a patient's quality of life. CONCLUSIONS: Although pain was the most frequent symptom, other health-related and social well-being issues significantly impacted patients' lives. Our validated patient-derived CReSP is a new instrument, specifically tailored to measure renal stone disease health outcomes from the patient's point of view.

Guideline adherence for the surgical treatment of T1 renal tumours correlates with hospital volume: an analysis from the British Association of Urological Surgeons Nephrectomy Audit.

OBJECTIVE: To assess European Association of Urology guideline adherence on the surgical management of patients with T1 renal tumours and the effects of centralisation of care. PATIENTS AND METHODS: Retrospective data from all kidney tumours that underwent radical nephrectomy (RN) or partial nephrectomy (PN) in the period 2012-2016 from the British Association of Urological Surgeons Nephrectomy Audit were retrieved and analysed. We assessed total surgical hospital volume (HV; RN and PN performed) per centre, PN rates, complication rates, and completeness of data. Descriptive analyses were performed, and confidence intervals were used to illustrate the association between hospital volume and proportion of PN. Chi- squared and Cochran-Armitage trend tests were used to evaluate differences and trends. RESULTS: In total, 13 045 surgically treated T1 tumours were included in the analyses. Over time, there was an increase in PN use (39.7% in 2012 to 44.9% in 2016). Registration of the Preoperative Aspects and Dimensions Used for an Anatomical (PADUA) complexity score was included in March 2016 and documented in 39% of cases. Missing information on postoperative complications appeared constant over the years (8.5-9%).  A clear association was found between annual HV and the proportion of T1 tumours treated with PN rather than RN (from 18.1% in centres performing <25 cases/year [lowest volume] to 61.8% in centres performing ≥100 cases/year [high volume]), which persisted after adjustment for PADUA complexity. Overall and major (Clavien-Dindo grade ≥III) complication rate decreased with increasing HV (from 12.2% and 2.9% in low-volume centres to 10.7% and 2.2% in high-volume centres, respectively), for all patients including those treated with PN. CONCLUSION: Closer guideline adherence was exhibited by higher surgical volume centres. Treatment of T1 tumours using PN increased with increasing HV, and was accompanied by an inverse association of HV with complication rate. These results support the centralisation of kidney cancer specialist cancer surgical services to improve patient outcomes.

Outcomes of Renal Tumors Treated by Image-Guided Percutaneous Cryoablation: Immediate and 3- and 5-Year Outcomes at a Regional Center.

OBJECTIVE. The purpose of this study was to evaluate the immediate and 3- and 5-year outcomes of patients with clinical stage T1 (cT1) biopsy-proven renal cell carcinoma (RCC) treated by image-guided percutaneous cryoablation at a regional interventional oncology center. MATERIALS AND METHODS. A prospectively maintained local interventional radiology database identified patients with cT1 RCC lesions that were treated by percutaneous cryoablation. Technical success, procedural complications (graded using the Clavien-Dindo classification system), and the residual unablated tumor rate were collated. Local tumor progression-free survival was estimated using Kaplan-Meier estimates. RESULTS. A total of 180 patients with 185 separate cT1 RCC lesions were identified. Mean patient age was 68.4 years (range, 34.1-88.9 years) and 52 patients (28.9%) were women. There were 168 (90.8%) and 17 (9.2%) cT1a and cT1b lesions, respectively, with a mean lesion size of 28.5 mm (range, 11-58 mm). Technical success was achieved in 183 of 185 (98.9%) patients. The major complication rate (Clavien-Dindo classification ≥ grade III) was 2.2% (four out of 185). Residual unablated tumor on the first follow-up scan was identified in four of 183 tumors (2.2%). Estimated local tumor progression-free survival at 3 and 5 years was 98.3% and 94.9%, respectively. No distant metastases or deaths attributable to RCC occurred. Mean estimated glomerular filtration rate (eGFR) before the procedure was 72.4 ± 18.5 (SD) mL/min/1.73 m2 and this was not statistically significantly different after the procedure (69.7 ± 18.8 mL/min/1.73 m2), at 1 year (70.7 ± 16.4 mL/min/1.73 m2), or at 2 years (69.8 ± 18.9 mL/min/1.73 m2) (p > 0.05). CONCLUSION. These data add to the accumulating evidence that image-guided cryoablation is an efficacious treatment for selected cT1 RCC with a low complication rate and ro bust 3- and 5-year outcomes.

Post-translational regulation of metabolism in fumarate hydratase deficient cancer cells.

Deregulated signal transduction and energy metabolism are hallmarks of cancer and both play a fundamental role in tumorigenesis. While it is increasingly recognised that signalling and metabolism are highly interconnected, the underpinning mechanisms of their co-regulation are still largely unknown. Here we designed and acquired proteomics, phosphoproteomics, and metabolomics experiments in fumarate hydratase (FH) deficient cells and developed a computational modelling approach to identify putative regulatory phosphorylation-sites of metabolic enzymes. We identified previously reported functionally relevant phosphosites and potentially novel regulatory residues in enzymes of the central carbon metabolism. In particular, we showed that pyruvate dehydrogenase (PDHA1) enzymatic activity is inhibited by increased phosphorylation in FH-deficient cells, restricting carbon entry from glucose to the tricarboxylic acid cycle. Moreover, we confirmed PDHA1 phosphorylation in human FH-deficient tumours. Our work provides a novel approach to investigate how post-translational modifications of enzymes regulate metabolism and could have important implications for understanding the metabolic transformation of FH-deficient cancers with potential clinical applications.

Contemporary surgical management of renal oncocytoma: a nation's outcome.

OBJECTIVE: To report on the contemporary UK experience of surgical management of renal oncocytomas. PATIENTS AND METHODS: Descriptive analysis of practice and postoperative outcomes of patients with a final histological diagnosis of oncocytoma included in The British Association of Urological Surgeons (BAUS) nephrectomy registry from 01/01/2013 to 31/12/2016. Short-term outcomes were assessed over a follow-up of 60 days. RESULTS: Over 4 years, 32 130 renal surgical cases were recorded in the UK, of which 1202 were oncocytomas (3.7%). Most patients were male (756; 62.9%), the median (interquartile range [IQR]) age was 66.8 (13) years. The median (IQR; range) lesion size was 4.1 (3; 1-25) cm, 43.5% were ≤4 cm and 30.3% were 4-7 cm lesions. In all, 35 patients (2.9%) had preoperative renal tumour biopsy. Most patients had minimally invasive surgery, either radical nephrectomy (683 patients; 56.8%), partial nephrectomy (483; 40.2%) or other procedures (36; 3%). One in five patients (243 patients; 20.2%) had in-hospital complications: 48 were Clavien-Dindo classification grade ≥III (4% of the total cohort), including three deaths. Two additional deaths occurred within 60 days of surgery. The analysis is limited by the study's observational nature, not capturing lesions on surveillance or ablated after biopsy, possible underreporting, short follow-up, and lack of central histology review. CONCLUSION: We report on the largest surgical series of renal oncocytomas. In the UK, the complication rate associated with surgical removal of a renal oncocytoma was not negligible. Centralisation of specialist services and increased utilisation of biopsy may inform management, reduce overtreatment, and change patient outcomes for this benign tumour.