Precision Surgery and Kidney Cancer: Knowledge of Genetic Alterations Influences Surgical Management

Hereditary Renal Cancer Syndromes

Familial kidney tumors represent a rare variety of hereditary cancer syndromes, although systematic gene sequencing studies revealed that as many as 5% of renal cell carcinomas (RCCs) are associated with germline pathogenic variants (PVs). Most instances of RCC predisposition are attributed to the loss-of-function mutations in tumor suppressor genes, which drive the malignant progression via somatic inactivation of the remaining allele. These syndromes almost always have extrarenal manifestations, for example, von Hippel-Lindau (VHL) disease, fumarate hydratase tumor predisposition syndrome (FHTPS), Birt-Hogg-Dubé (BHD) syndrome, tuberous sclerosis (TS), etc. In contrast to the above conditions, hereditary papillary renal cell carcinoma syndrome (HPRCC) is caused by activating mutations in the MET oncogene and affects only the kidneys. Recent years have been characterized by remarkable progress in the development of targeted therapies for hereditary RCCs. The HIF2aplha inhibitor belzutifan demonstrated high clinical efficacy towards VHL-associated RCCs. mTOR downregulation provides significant benefits to patients with tuberous sclerosis. MET inhibitors hold promise for the treatment of HPRCC. Systematic gene sequencing studies have the potential to identify novel RCC-predisposing genes, especially when applied to yet unstudied populations.

Guidelines on Germline Testing for Urologic Tumor Syndromes

In the expanding precision medicine landscape, along with improvements in and the availability of testing, the use of genetics in the evaluation and treatment of patients has increased significantly. Multiple urologic cancers in different organ systems associated with an inherited gene mutation have been described. As these mutations can impact screening and treatment decisions for patients and their families, it is important for providers to be familiar with the current guidelines for germline testing. Here we summarize the current guidelines regarding germline testing for patients with suspected urologic tumor syndromes. PATIENT SUMMARY: Several cancers of the genitourinary tract can be associated with inherited genetic mutations. Knowledge of when to test for these mutations has implications for both treatment and screening of patients and their family members at risk of genitourinary cancers.

Renal Neoplasms in Young Adults

Renal cell carcinoma (RCC) is usually diagnosed in older adults (the median age of diagnosis is 64 years). Although less common in patients younger than 45 years, RCCs in young adults differ in clinical manifestation, pathologic diagnosis, and prognosis. RCCs in young adults are typically smaller, are more organ confined, and manifest at lower stages of disease. The proportion of clear cell RCC is lower in young adults, while the prevalence of familial renal neoplastic syndromes is much higher, and genetic testing is routinely recommended. In such syndromic manifestations, benign-appearing renal cysts can harbor malignancy. Radiologists need to be familiar with the differences of RCCs in young adults and apply an altered approach to diagnosis, treatment, and surveillance. For sporadic renal neoplasms, biopsy and active surveillance are less often used in young adults than in older adults. RCCs in young adults are overall associated with better disease-specific survival after surgical treatment, and minimally invasive nephron-sparing treatment options are preferred. However, surveillance schedules, need for biopsy, decision for an initial period of active surveillance, type of surgery (enucleation or wide-margin partial nephrectomy), and utilization of ablative therapy depend on the presence and type of underlying familial renal neoplastic syndrome. In this pictorial review, syndromic, nonsyndromic, and newer RCC entities that are common in young adults are presented. Their associated unique epidemiology, characteristic imaging and pathologic traits, and key aspects of surveillance and management of renal neoplasms in young adults are discussed. The vital role of the informed radiologist in the multidisciplinary management of RCCs in young adults is highlighted. Online supplemental material is available for this article. ^©RSNA, 2022.

X-Capsular Incision for Tumor Enucleation (X-CITE)-Technique: A Method to Maximize Renal Parenchymal Preservation for Completely Endophytic Renal Tumors

OBJECTIVE

To describe the X-Capsular Incision for Tumor Enucleation (X-CITE) technique to resect endophytic renal tumors while preserving the overlying renal parenchyma.

SUBJECTS AND METHODS

We reviewed 1-year outcomes of 12 consecutive patients with a history of bilateral or multifocal renal tumors who presented to our institution with completely endophytic renal masse(s) between August 2017 and August 2018. Endophytic tumors were resected by making an X-shaped incision in the renal capsule and developing parenchymal flaps overlying the tumor pseudocapsule. Following tumor enucleation, the overlying parenchymal flaps were reapproximated.

RESULTS

Median follow up was 19.9 months (range 10.6-14.9). Most patients also had additional exophytic tumors with a median of 5 renal tumors removed per operation with a median largest renal tumor size of 3.2 cm. No intraoperative or postoperative complications occurred. There was no decline in renal function after surgery when comparing median pre- and 12-month postoperative eGFR (94.5 vs 91.5, P= 0.18).). Postoperative nuclear mercaptoacetyltriglycine (MAG-3) renal scans demonstrated equal differential kidney function after surgery. Limitations include short-term follow-up and referral bias at center specializing in multi-focal kidney surgery.

CONCLUSION

The X-Capsular Incision for Tumor Enucleation technique is feasible, safe and effective with minimal collateral damage in the treatment of completely endophytic renal masses. Further investigation should identify which patients may benefit from this procedure and explore intermediate and long-term outcomes.