Current Management for Pediatric Urologic Oncology

PI3K/AKT/mTOR Dysregulation and Reprogramming Metabolic Pathways in Renal Cancer: Crosstalk with the VHL/HIF Axis

Renal cell carcinoma (RCC) represents 85-95% of kidney cancers and is the most frequent type of renal cancer in adult patients. It accounts for 3% of all cancer cases and is in 7th place among the most frequent histological types of cancer. Clear cell renal cell carcinoma (ccRCC), accounts for 75% of RCCs and has the most kidney cancer-related deaths. One-third of the patients with ccRCC develop metastases. Renal cancer presents cellular alterations in sugars, lipids, amino acids, and nucleic acid metabolism. RCC is characterized by several metabolic dysregulations including oxygen sensing (VHL/HIF pathway), glucose transporters (GLUT 1 and GLUT 4) energy sensing, and energy nutrient sensing cascade. Metabolic reprogramming represents an important characteristic of the cancer cells to survive in nutrient and oxygen-deprived environments, to proliferate and metastasize in different body sites. The phosphoinositide 3-kinase-AKT-mammalian target of the rapamycin (PI3K/AKT/mTOR) signaling pathway is usually dysregulated in various cancer types including renal cancer. This molecular pathway is frequently correlated with tumor growth and survival. The main aim of this review is to present renal cancer types, dysregulation of PI3K/AKT/mTOR signaling pathway members, crosstalk with VHL/HIF axis, and carbohydrates, lipids, and amino acid alterations.

Nephron sparing surgery outcomes in Wilms' tumor: is it ready for primetime?

PURPOSE

Radical nephrectomy is the gold standard in Wilms tumor (WT) treatment and is combined with adjuvant treatment in early stage disease or performed after neo adjuvant therapy in advanced disease. With the development of novel adjuvant and neoadjuvant therapeutic strategies, there is increasing interest in organ preserving procedures in several adult malignancies. Potential long-term complications of living with a single kidney include hyperfiltration syndrome, hypertension, and fluid retention. If NSS (Nephron Sparing Surgery) were to be adopted for the treatment of WT it would be necessary to preserve the gains in Overall Survival (OS) seen with current treatment protocols. With this in mind we undertook a study of outcomes of NSS performed in the USA using a large population-based registry.

METHODS

We retrospectively queried the SEER Research Plus 18-registries Database 2010-2018 for patients 18 years old or younger with Wilms tumor as determined by ICD-O-3 code 8960. Clinical and demographic data was extracted, and statistical analysis was performed in GraphPad PRISM 9 with bivariate analysis and log-rank analysis to determine survival.

RESULTS

1087 patients with Wilms tumor were identified. 73 (6.72%) underwent nephron-sparing surgery. The final cohort consisted of 45 patients (64%) who underwent unilateral NSS and 25 patients (36%) who underwent bilateral NSS. Three were excluded from analysis due to non-renal origin of tumor. Mean age was 3.214 years (std dev 3.807). Demographics were similar between the groups, apart from younger age associated with bilateral tumor (p = 0.0441). No differences were found between radiation use (p = 0.4280), chemotherapy use (p = 0.5479), tumor size (p = 0.2186), positive regional lymph nodes (p = 0.707). Log-rank analysis demonstrated that cancer-specific survival was not significantly different between unilateral and bilateral NSS or radical nephrectomy (p = 0.4539).

CONCLUSION

NSS may preserve renal function long-term, an important consideration in the pediatric population. Prospective study is necessary to select the appropriate patient subsets who may benefit from NSS in WT.

Identification of Nephrogenic Therapeutic Biomarkers of Wilms Tumor Using Machine Learning

Wilms tumor is the most common renal malignancy in children, with a survival rate of more than 90%; however, treatment outcomes for certain patient subgroups, such as those with bilateral and recurrent diseases, remain significantly below this survival rate. Therefore, it remains essential to identify new biomarkers and develop effective therapeutic strategies. Based on the Therapeutically Applicable Research to Generate Effective Treatments and Gene Expression Omnibus RNA microarray datasets, we have identified eight differentially expressed genes in Wilms tumors as renal-specific in 33 randomly selected adult tumors. The risk model, constructed using survival forest and multivariate Cox regression, can effectively predict the prognosis; the risk score is an independent prognostic factor in Wilms tumor. Gene set enrichment analysis showed that most of the signature genes were involved in regulating human development-related pathways. At the same time, patients in the high-risk group exhibited more sensitive immunological and chemotherapeutic properties than those in the low-risk group. These results provide new insights into personalized and precise Wilms tumor treatment strategies.

Partial orchiectomy vs. radical orchiectomy for pediatric testis tumors

While radical orchiectomy remains the gold standard for testicular cancer, partial orchiectomy has become a well-accepted organ-sparing approach for benign testicular tumors in pre-pubertal patients. The aims of testicular-sparing surgery include prevention of over-treatment, preservation of future hormonal and reproductive function, and provision of a durable cure. For pre-pubertal patients, who have a high likelihood of benign lesions, partial orchiectomy provides effective treatment, owing to the high reliability of scrotal ultrasound (US) and intraoperative frozen section. In adolescent and young adult patients, who are more likely to harbor malignant pathology, the role of partial orchiectomy is less clear. Testis-sparing surgery is being reported with greater frequency in the adult literature for small testicular masses and for situations in which radical orchiectomy would result in an anorchia. More recently, a testis-sparing approach has also been described for carefully-selected post-pubertal pediatric patients. This review will highlight the role of partial orchiectomy in pediatric patients (<18 years old).

Management of Testicular Torsion and a Contralateral Testicular Mass Presenting Synchronously

Testicular masses found in prepubertal males are often benign in nature. This has led to an increase in the use of testis-sparing surgery. Testicular torsion is considered a urologic emergency that requires immediate surgical intervention. Based off literature review, it is rare for these unique entities to present synchronously in a single patient. This report demonstrates that in the pediatric population it is possible to safely treat a suspected benign testicular mass with testis sparing mass enucleation if it presents synchronously with testicular torsion in the contralateral testis.

Complications Following Nephron-Sparing Surgery for Wilms Tumor

PURPOSE

Because of the increasing use of nephron-sparing surgery (NSS) in bilateral Wilms tumor, we sought to review the early postoperative complications associated with NSS.

METHODS

A retrospective review of patients who underwent NSS at our institution from 2000 to 2017 was performed. For comparison, a cohort of patients who underwent radical nephrectomy (RN) was also reviewed. Early (30-day) postoperative complications and oncologic outcomes were assessed.

RESULTS

Fifty-five patients underwent either bilateral (46) NSS or unilateral (9) NSS owing to prior resection or congenital solitary kidney. Fifty-four patients who underwent unilateral RN were also evaluated. Twenty NSS patients (36.4%) experienced 21 postoperative complications, including prolonged urine leak (9), infection (8), transient renal insufficiency (1), and intussusception (3). Seven RN patients (13.0%) experienced surgical complications, including infection (4) and intussusception (3). Average intraoperative blood loss was significantly greater in NSS as compared to RN (483.51 ± 337.92 mL and 278.15 mL ± 390.25, respectively, p < 0.001), as was the incidence of positive tumor resection margins (20 [36.4%] and 12 [22.2%], respectively, (p = 0.037).

CONCLUSIONS

In our experience, prolonged urine leak, intraoperative blood loss, and positive margins were more frequent in patients undergoing NSS as compared to RN. However, the complications were successfully managed, suggesting that an aggressive approach to NSS in patients with bilateral Wilms tumor is safe and appropriate.

LEVEL OF EVIDENCE

Level III TYPE OF STUDY: Treatment study.

Adolescent and Young Adult Testicular Germ Cell Tumors: Special Considerations

While testicular germ cell tumors (T-GCTs) make up only 0.5% of pediatric malignancies and less than 2% of adult malignancies, they comprise 14% of adolescent malignancies, making it the most common solid tumor in this age group. The transition in incidence at this age is also accompanied by a transition in tumor histology with adolescents having mostly pure embryonal carcinoma and mixed nonseminomatous germ cell tumors. Similar to T-GCTs of all ages, surgical excision with orchiectomy is the standard initial step in treatment. Chemotherapy, retroperitoneal lymph node dissection, and targeted treatment of distant metastases make even widely disseminated disease treatable and curable. For this reason, in many ways, the future focus has expanded beyond survival alone to emphasize quality of life issues such as fertility and hypogonadism. However, adolescents remain the age group least studied or understood as they fall in between the ages included in most study designs. Also, they require the most psychosocial support because of the challenges unique to the adolescent period. In this review, we aim to highlight the known outcome data for T-GCTs in this population and also to discuss the unique aspects of treatment and support for this age group.

When Chemotherapy Is Not Enough-Management of Prostatic Embryonal Rhabdomyosarcoma in an Infant

A baby boy was diagnosed with embryonal rhabdomyosarcoma causing left hydroureteronephrosis. A loop ureterostomy was performed, and the infant was treated per the RMS13 protocol. After 3 months of chemotherapy, the infant's tumor burden increased, and he underwent radical cystoprostatectomy and right-to-left transureteroureterostomy (end-to-end fashion utilizing the distal limb of his ureterostomy). This innovative method was utilized because the infant's tumor burden was too large to be treated effectively and safely with radiation. One year later, the infant has no evidence of disease. This demonstrates that optimal management of rhabdomyosarcoma is still unknown; therefore, each child warrants an individualized approach for optimal outcomes.