Nephron-sparing surgery for multifocal and hereditary renal tumors.

PURPOSE OF REVIEW: Despite the controversy surrounding the benefits of nephron-sparing surgery, multiple absolute indications for nephron-sparing surgery still exist, including the classic indications of hereditary and bilateral kidney tumors. RECENT FINDINGS: Multiple genetic mutations have been identified which lead to hereditary kidney cancer conditions. These are briefly reviewed because the surgical management of hereditary kidney tumors depends on the genetic and histologic subtypes involved. Clear understanding of these hereditary conditions is crucial for proper surgical management of these tumors. SUMMARY: Complex partial nephrectomy for multiple renal tumors, or multiplex partial nephrectomy, requires not only exceptional surgical skills but expertise of numerous nonsurgical methodologies, such as hands-on intraoperative ultrasonography and interpretation of multiple imaging modalities. In addition, multidisciplinary management is crucial for optimal outcomes in patient care. This review evaluates the most advanced surgical techniques and perioperative management required to successfully care for these challenging cases.

Clinical and Molecular Characterization of Microphthalmia-associated Transcription Factor (MITF)-related Renal Cell Carcinoma.

OBJECTIVES: To characterize the clinical presentation, genomic alterations, pathologic phenotype and clinical management of microphthalmia-associated transcription factor (MITF) familial renal cell carcinoma (RCC), caused by a member of the TFE3, TFEB, and MITF family of transcription factor genes. METHODS: The clinical presentation, family history, tumor histopathology, and surgical management were evaluated and reported herein. DNA sequencing was performed on blood DNA, tumor DNA and DNA extracted from adjacent normal kidney tissue. Copy number and gene expression analyses on tumor and normal tissues were performed by Real-Time Polymerase chain reaction. TCGA gene expression data were used for comparative analysis. Protein expression and subcellular localization were evaluated by immunohistochemistry. RESULTS: Germline genomic analysis identified the MITF p.E318K variant in a patient with bilateral, multifocal type 1 papillary RCC and a family history of RCC. All tumors displayed the MITF variant and were characterized by amplification of chromosomes 7 and 17, hallmarks of type 1 papillary RCC. We demonstrated that MITF p.E318K variant results in altered transcriptional activity and that downstream targets of MiT family members, such as GPNMB, are dysregulated in the tumors. CONCLUSION: Association of the pathogenic MITF variant with bilateral and multifocal type 1 papillary RCC in this family supports its role as a risk allele for the development of RCC and emphasizes the importance of screening for MITF variants irrelevant of the RCC histologic subtype. This study identifies potential biomarkers for the disease, such as GPNMB expression, that may facilitate the development of targeted therapies for patients affected with MITF-associated RCC.

Multifocal Renal Cell Carcinomas With Somatic IDH2 Mutation: Report of a Previously Undescribed Neoplasm.

Renal cell carcinoma (RCC) is a heterogenous disease composed of several different cancer types characterized by distinct histologies and genetic alterations, including mutation of the Krebs cycle enzyme genes for fumarate hydratase and succinate dehydrogenase (SDH). This report describes a patient with multifocal renal tumors that presented with a novel, biphasic histologic morphology with one component consisting of small cells growing in a diffuse pattern occasionally forming glandular and cystic structures, reminiscent of type 1 papillary RCC, and the other component having larger cells with abundant eosinophilic and clear cytoplasm and appearing in a solid pattern of growth. Genetic analysis of multiple tumors showed that all had a somatic mutation of the IDH2 gene that created the known pathogenic, gain-of-function p.R172M alteration that results in abnormal accumulation of the oncometabolite 2-hydroxyglutarate (2-HG). Analysis of multiple tumors demonstrated highly elevated levels of 2-HG and a CpG island methylator phenotype that is characteristic of 2-HG-related inhibition of the Ten-eleven translocation (TET) family of DNA demethylases. In combination with fumarate hydratase-deficient and succinate dehydrogenase-deficient RCCs that have increased levels of the fumarate and succinate oncometabolites, respectively, the mutation of isocitrate dehydrogenase 2 represents the third Krebs cycle enzyme alteration to be associated with oncometabolite-induced RCC tumorigenesis. This study associates the discovery of a new histologic presentation of RCC with the first report of an IDH2 gain-of-function mutation in RCC.

LDH-A inhibition, a therapeutic strategy for treatment of hereditary leiomyomatosis and renal cell cancer.

The genetic basis for the hereditary leiomyomatosis and renal cell cancer syndrome is germ-line inactivating mutation in the gene for the Krebs/tricarboxylic acid cycle enzyme, fumarate hydratase (FH), the enzyme that converts fumarate to malate. These individuals are predisposed to development of leiomyomas of the skin and uterus as well as highly aggressive kidney cancers. Inhibition of FH should result in significant decrease in oxidative phosphorylation necessitating that glycolysis followed by fermentation of pyruvate to lactate will be required to provide adequate ATP as well as to regenerate NAD+. Moreover, FH deficiency is known to up-regulate expression of hypoxia-inducible factor (HIF)-1alpha by enhancing the stability of HIF transcript. This leads to activation of various HIF-regulated genes including vascular endothelial growth factor and glucose transporter GLUT1 and increased expression of several glycolytic enzymes. Because lactate dehydrogenase-A (LDH-A), also a HIF-1alpha target, promotes fermentative glycolysis (conversion of pyruvate to lactate), a step essential for regenerating NAD+, we asked whether FH-deficient cells would be exquisitely sensitive to LDH-A blockade. Here, we report that hereditary leiomyomatosis and renal cell cancer tumors indeed overexpress LDH-A, that LDH-A inhibition results in increased apoptosis in a cell with FH deficiency and that this effect is reactive oxygen species mediated, and that LDH-A knockdown in the background of FH knockdown results in significant reduction in tumor growth in a xenograft mouse model.

A comparison of outcomes for standard and multiplex partial nephrectomy in a solitary kidney: The National Cancer Institute experience.

OBJECTIVES: To study the short and intermediate surgical, renal functional, and oncologic outcomes of multiplex partial nephrectomy (mPN) and standard partial nephrectomy (sPN) in the setting of a solitary kidney. PATIENTS AND METHODS: Review of a prospectively maintained database of patients undergoing solitary kidney partial nephrectomy at our institution was performed. Patients were stratified into 2 cohorts: mPN-where 3 or more renal tumors were resected and sPN-where 1 or 2 tumors were resected. Perioperative, renal functional, and oncological outcomes were compared. RESULTS: Ninety-three patients with a solitary kidney underwent a total of 121 surgical procedures; 43 (35.5%) were sPN and 78 (64.4%) were mPN. The total and major (Clavien Grade III and IV) complication rates between sPN and mPN were similar (57.1% vs. 70.1%, P = 0.2; 31.0% vs. 35.1%, P = 0.3). At 12 months post-op, the percentage of patients with eGFR > 45 was similar in each group (sPN 87.0%, mPN 73.7%; P = 0.2), and long-term hemodialysis rates were 4.7% and 6.4%, respectively. Completion nephrectomy was performed in 2.3% of sPN and 2.6% of mPN. At a median follow-up of 40.1 months, the metastasis rate was 8.6% in the sPN group and 4.1% in the mPN group (P = 0.4). CONCLUSIONS: Partial nephrectomy in the setting of a solitary kidney can effectively preserve renal function. The renal functional and oncologic outcomes were similar in sPN and mPN, with low hemodialysis rates and complication rates within the expected range of these operations. Three or more tumors in a solitary kidney should not be a contraindication for nephron sparing surgery.

Assessment of tumor growth in pancreatic neuroendocrine tumors in von Hippel Lindau syndrome.

BACKGROUND: The incidence of pancreatic neuroendocrine tumors (PNETs) is increasing, but only a subset of these heterogeneous tumors will progress to malignant disease, which is associated with a poor prognosis. Currently, there are limited data on the natural history of these tumors and it is difficult to determine which patients require surgical intervention because the risk of metastatic disease cannot be accurately determined. STUDY DESIGN: We conducted a prospective study of 87 patients with von Hippel Lindau syndrome-associated solid pancreatic lesions to determine the natural history of these tumors with biochemical testing, follow-up anatomic and functional imaging, and advanced imaging analysis, with a median follow-up of 4 years. RESULTS: Approximately 20% of consecutive tumor measurements during follow-up were decreased in size and 20% showed no change. This included 2 of 4 surgically proven malignant tumors, which had a net decrease in tumor size over time. Tumor volume, as derived from greatest diameter and volumetric measurements, showed good correlation to pathology tumor measurement of surgically resected tumors (Spearman rank correlation ρ = 0.72, p = 0.0011, and ρ = 0.83, p < 0.0001, respectively). Tumor density measurement had an inverse relationship with tumor size (Spearman rank correlation -0.22, p = 0.0047). A tumor density cutoff of 200 was 75% specific for malignant tumors. CONCLUSIONS: Pancreatic neuroendocrine tumors demonstrate a nonlinear growth pattern, which includes periods of no growth and apparent decrease in size by imaging. These growth patterns are variable and are not associated with tumor grade and malignancy. Tumor density, as measured in this cohort, may offer a specific diagnostic tool for malignant disease.

Comparison of 6-18F-fluoro-L-DOPA, 18F-2-deoxy-D-glucose, CT, and MRI in patients with pancreatic neuroendocrine neoplasms with von Hippel-Lindau disease.

INTRODUCTION: There are limited data on the utility of 6-(18)F-fluoro-l-3,4-dihydroxyphenylalanine ((18)F-DOPA) and (18)F-2-deoxy-d-glucose ((18)F-FDG) in the workup of patients with pancreatic neuroendocrine tumors (PNETs). The aim of our study was to determine the accuracy of (18)F-DOPA and (18)F-FDG to detect PNETs in patients with von Hippel-Lindau disease (vHL). METHODS: We studied prospectively 69 patients with a diagnosis of vHL and pancreatic lesion(s) using computed tomography (CT), magnetic resonance imaging (MRI), (18)F-FDG, and (18)F-DOPA. Clinical, genetic, and laboratory characteristics were analyzed to determine association with imaging study results. RESULTS: In sum, 40 patients underwent evaluation by all 4 modalities; 98 PNETs and 55 PNETs were identified on CT and MRI, respectively. Only 11 of the 98 lesions (11%) were positive on (18)F-DOPA and 45 of the 98 (46%) lesions were positive on (18)F-FDG. There were 13 (18)F-DOPA and 26 (18)F-FDG avid extrapancreatic lesions. One patient underwent resection of an (18)F-DOPA avid extrapancreatic lesion in the lung, with pathology demonstrating a NET. There was no association between (18)F-DOPA and (18)F-FDG avidity and tumor size, age, gender, vHL mutation, or serum chromogranin A level. CONCLUSION: (18)F-FDG and MRI may be adjuncts to CT in identifying PNETs and metastatic disease. (18)F-DOPA has limited value in identifying PNETs in patients with vHL, but may be useful for identifying extrapancreatic NET lesions.