Wilms Tumor

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Basics

Description

  • Most common renal tumor in children; fifth most common pediatric malignancy
  • An embryonal renal neoplasm containing blastemal, stromal, or epithelial cell types, usually affecting children <5 years of age.
  • Staging: In the United States, Children’s Oncology Group (COG) Renal Tumor Committee (formerly National Wilms Tumor Study [NWTS] group) staging is done pretreatment. In Europe/Asia, staging is done after neoadjuvant chemotherapy (1).
  • COG Renal Tumor Committee Stage (incidence) (1):
    • I: completely excised tumor limited to kidney; negative lymph nodes (43%)
    • II: completely excised tumor extends beyond kidney capsule or renal sinus vessels contain tumor; atriocaval thrombus if removed en bloc with tumor; negative lymph nodes (20%)
    • III: residual nonhematogenous tumor confined to abdomen (spillage of tumor or previous biopsy, peritoneal implants, extension beyond resection region, atriocaval thrombus above diaphragm not removed en bloc with kidney) or positive lymph nodes (21%)
    • IV: hematogenous metastases (lung most common, liver, brain, or bones) or lymph node involvement outside the abdomen or pelvis (11%)
    • V: bilateral renal involvement (5%)
  • System(s) affected: renal/urologic
  • Synonym(s): nephroblastoma

Pediatric Considerations
Occurs predominately in children; rare incidence in late adolescence and adults

Epidemiology

Incidence
  • Represents 6–7% of all childhood cancers
  • Wilms tumor comprises 95% of all renal cancers in children <15 years.
  • 650 cases diagnosed annually, with incidence of 7.8 cases per 1 million children
  • Bilateral renal involvement approximately 5%.
  • Frequency higher in black children.
  • Predominant age: median age of 36.5 months:
    • >80% diagnosed before 5 years of age.
    • Diagnosis for bilateral Wilms tumor (mean 31 months) than unilateral tumor (mean 44 months).
  • Predominant sex: female > male (1.1:1)
    • Higher rate of bilateral Wilms tumor in females (1.7:1) (1)

Prevalence
  • United States: 0.69 per 100,000 children
  • Globally: 1 per 10,000 children

Etiology and Pathophysiology

  • Thought to be more than one genetic alteration affecting embryologic renal development or epigenetic regulation.
  • Majority occur sporadically; familial inheritance <2% (1)

Genetics
  • Tumors display recurrent gene mutations involved in either early renal development or epigenetic regulation (e.g., chromatin modification, transcription regulation, miRNA).
  • 1/3 of tumors involve mutations of WT1, CTNNB1, or WTX genes (1).

Risk Factors

  • Increased predisposition associated with syndromes (e.g., Beckwith-Wiedemann, WAGR, Denys-Drash)
  • Race: more frequent in black children; rare in Asian
  • Sex: more frequent and higher rate of bilateral in females

General Prevention

  • 2016 American Association for Cancer Research (AACR) Childhood Cancer Predisposition Workshop recommends uniform screening for all syndromes associated with >1% risk of Wilms tumor (1):
    • Routine screening with serial renal ultrasound (US) at 3-month intervals, usually until age 8
  • Genetic counseling recommended for children with Wilms tumor and (1):
    • One major abnormality: overgrowth syndromes, hemihyperplasia, aniridia, mental retardation, diffuse mesangial sclerosis; or
    • Two minor malformations - inguinal or umbilical hernia, hypospadias, renal abnormalities, ectopic testis

Commonly Associated Conditions

  • Associated conditions grouped into overgrowth and non-overgrowth categories
  • Overgrowth syndromes and conditions (1)
    • Beckwith-Wiedemann syndrome
    • Isolated hemihyperplasia
    • Pearlman syndrome
    • Simpson-Golabi-Behmal syndrome
    • CLOVES syndrome
    • Sotos syndrome
  • Non-overgrowth syndromes and conditions (1)
    • Denys Drash and Frasier
    • WAGR syndrome
    • Sporadic
    • Familial Wilms tumor
    • Bohring-Opitz syndrome
    • Bloom syndrome
    • Li-Fraumeni syndrome
    • Fanconi anemia
    • Alagille syndrome
    • Trisomy 18
    • Genitourinary

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Basics

Description

  • Most common renal tumor in children; fifth most common pediatric malignancy
  • An embryonal renal neoplasm containing blastemal, stromal, or epithelial cell types, usually affecting children <5 years of age.
  • Staging: In the United States, Children’s Oncology Group (COG) Renal Tumor Committee (formerly National Wilms Tumor Study [NWTS] group) staging is done pretreatment. In Europe/Asia, staging is done after neoadjuvant chemotherapy (1).
  • COG Renal Tumor Committee Stage (incidence) (1):
    • I: completely excised tumor limited to kidney; negative lymph nodes (43%)
    • II: completely excised tumor extends beyond kidney capsule or renal sinus vessels contain tumor; atriocaval thrombus if removed en bloc with tumor; negative lymph nodes (20%)
    • III: residual nonhematogenous tumor confined to abdomen (spillage of tumor or previous biopsy, peritoneal implants, extension beyond resection region, atriocaval thrombus above diaphragm not removed en bloc with kidney) or positive lymph nodes (21%)
    • IV: hematogenous metastases (lung most common, liver, brain, or bones) or lymph node involvement outside the abdomen or pelvis (11%)
    • V: bilateral renal involvement (5%)
  • System(s) affected: renal/urologic
  • Synonym(s): nephroblastoma

Pediatric Considerations
Occurs predominately in children; rare incidence in late adolescence and adults

Epidemiology

Incidence
  • Represents 6–7% of all childhood cancers
  • Wilms tumor comprises 95% of all renal cancers in children <15 years.
  • 650 cases diagnosed annually, with incidence of 7.8 cases per 1 million children
  • Bilateral renal involvement approximately 5%.
  • Frequency higher in black children.
  • Predominant age: median age of 36.5 months:
    • >80% diagnosed before 5 years of age.
    • Diagnosis for bilateral Wilms tumor (mean 31 months) than unilateral tumor (mean 44 months).
  • Predominant sex: female > male (1.1:1)
    • Higher rate of bilateral Wilms tumor in females (1.7:1) (1)

Prevalence
  • United States: 0.69 per 100,000 children
  • Globally: 1 per 10,000 children

Etiology and Pathophysiology

  • Thought to be more than one genetic alteration affecting embryologic renal development or epigenetic regulation.
  • Majority occur sporadically; familial inheritance <2% (1)

Genetics
  • Tumors display recurrent gene mutations involved in either early renal development or epigenetic regulation (e.g., chromatin modification, transcription regulation, miRNA).
  • 1/3 of tumors involve mutations of WT1, CTNNB1, or WTX genes (1).

Risk Factors

  • Increased predisposition associated with syndromes (e.g., Beckwith-Wiedemann, WAGR, Denys-Drash)
  • Race: more frequent in black children; rare in Asian
  • Sex: more frequent and higher rate of bilateral in females

General Prevention

  • 2016 American Association for Cancer Research (AACR) Childhood Cancer Predisposition Workshop recommends uniform screening for all syndromes associated with >1% risk of Wilms tumor (1):
    • Routine screening with serial renal ultrasound (US) at 3-month intervals, usually until age 8
  • Genetic counseling recommended for children with Wilms tumor and (1):
    • One major abnormality: overgrowth syndromes, hemihyperplasia, aniridia, mental retardation, diffuse mesangial sclerosis; or
    • Two minor malformations - inguinal or umbilical hernia, hypospadias, renal abnormalities, ectopic testis

Commonly Associated Conditions

  • Associated conditions grouped into overgrowth and non-overgrowth categories
  • Overgrowth syndromes and conditions (1)
    • Beckwith-Wiedemann syndrome
    • Isolated hemihyperplasia
    • Pearlman syndrome
    • Simpson-Golabi-Behmal syndrome
    • CLOVES syndrome
    • Sotos syndrome
  • Non-overgrowth syndromes and conditions (1)
    • Denys Drash and Frasier
    • WAGR syndrome
    • Sporadic
    • Familial Wilms tumor
    • Bohring-Opitz syndrome
    • Bloom syndrome
    • Li-Fraumeni syndrome
    • Fanconi anemia
    • Alagille syndrome
    • Trisomy 18
    • Genitourinary

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