Topics in 10: Wilms Tumor

Space: StayCurrentMD Published: 2019-08-07

Topic overview

Drs Andrew Davidoff, Todd Ponsky and Rae Hanke come together to provide you the essentials on the diagnosis and management of Wilms Tumor.

Intro and outro tracks are adapted from "I dunno" by grapes, featuring J Lang, Morusque. Artist URL: ccmixter.org/files/grapes/16626

What is Wilms tumor?

Second most common intra-abdominal tumor in children
5th most common tumor in children overall
75% of tumors are found in children < 5 years
Peak incidence at 2-3 years old
Survival is >90% overall

Affected by histology
Categorized as favorable or unfavorable (Anaplastic)
Anaplastic is unfavorable, found in about 10% of cases, but causes over 50% of mortality from Wilm’s tumor

How does it present?

Asymptomatic abdominal mass
Other signs/symptoms (seen in about 25%)
Malaise, abdominal pain, hypertension, microscopic or gross hematuria

What do you do to work up suspected renal mass?

Start with an abdominal ultrasound
CT abdomen/pelvis is the definitive imaging modality

Confirm solid renal mass
Ensure there are two kidneys
Rule out synchronous bilateral disease
Evaluate for intravascular extension (found in 6%)

Consider echocardiogram if intracardiac thrombus is suspected
Chest CT to evaluate for lung metastasis (most common site)

Staging: surgical pathological staging determined by the Children’s Oncology Group (COG)

Stage 1: Localized Wilm’s confined to the renal capsule
Stage 2: Penetrate renal capsule, but have been resected with negative margins
Stage 3: Biopsy or rupture (pre-operative or intra-operative), positive margins (residual disease), lymph node involvement, or use of preop chemo
Stage 4: metastasis (12% of patients)

Determine local stage—dictates whether you should use abdominal radiation or not and to what field

Stage 5: synchronous bilateral tumors

Need to determine local stage for each side

Treatment

Unilateral disease:

Surgery: Remove primary tumor by Radical nephrectomy with regional lymph node sampling

Most are resectable at presentation
Node sampling: Critical!

Absence of abnormal nodes on preoperative imaging or intraoperative inspection are NOT predictive
Failure to sample automatically upstages disease to Stage 3
Nodal metastasis is associated with likelihood of relapse and poorer prognosis
Failure to operate before neoadjuvant chemotherapy automatically upstages disease to Stage 3 [potentially inducing long-term toxicity unnecessarily]

No partial nephrectomy or laparoscopic nephrectomy in unilateral non-syndromic disease UNLESS you are a part of a clinical trial

Chemotherapy or Radiation?

Stage 1 & 2 (favorable staging): Adjuvant chemotherapy is limited to Vincristine and Actinomycin B
Stage 1 with tumor/kidney <550 grams and age <2 yrs: don’t require adjuvant chemotherapy!
Research being conducted to potentially raise this age limit and weight!
Stage 3 & 4: (favorable staging): Stage 1 & 2 chemotherapy PLUS Doxorubicin with flank irradiation
Anaplastic histology:

Significantly worse outcome and require more intense chemotherapy
Focal and diffuse classifications influence specific neoadjuvant therapy

Bilateral Wilms tumor = Stage 5

Bilateral synchronous disease found in 5% of patients
Increased risk of renal failure
Biopsy not required in bilateral solid renal masses because diagnosis is very likely Wilm’s tumor

Studies show the biopsy rarely shows dysplasia if it does exist
Biopsy in bilateral disease doesn’t upstage the disease like it does in unilateral disease

Neoadjuvant chemotherapy: to shrink tumor prior to surgery—preserve normal renal function

Vincristine, Actinomycin B, and Doxorubicin: Similar to Stage 3 & 4 favorable histology adjuvant regimen

Surgery:

Consider bilateral nephron sparing surgery in all bilateral tumors
Operate 6-12 weeks after neoadjuvant chemotherapy (anything longer is discouraged)

Solitary kidney: similar to bilateral synchronous chemotherapy regimen

Unilateral tumor but predisposed to developing second tumor
WAGER or Beckwith-Weidemann syndrome
Chemotherapy regimen usually doesn’t include Doxorubicin
Radiation isn’t mandated like it is in unilateral Wilm’s tumor**

Intravascular tumor extension

Challenging
Determined by preoperative imaging and confirmed intraoperatively
Management depends on extent:

Renal vein and proximal IVC: remove enbloc with kidney tumor
Further into IVC but below hepatic veins: can be withdrawn after obtaining proximal and distal control
Above hepatic veins/into right atrium:

Has higher rate of morbidity
Need neoadjuvant chemotherapy
If it persists after chemotherapy, likely requires cardiopulmonary bypass to remove the extent of disease

Metastasis

Found in 12% of patients at diagnosis
Spread hematogenously, with 80% metastasis found in lungs
Response-based chemotherapy approach:

Give three drug chemotherapy regimen and repeat imaging at week six
Rapid responders: Disappears radiographically or biopsy shows noviable tumor in residual nodules

Continue on chemotherapy but don’t need pulmonary radiation

Slow or incomplete responders: no complete resolution at 6 weeks

More intense chemotherapy and whole lung radiation

Wilms Tumor Clinical Pearls:

Most common renal tumor in children
Outstanding overall survival at greater than 90%
Worse with anaplastic histology
Management/Treatment:

Radical nephrectomy with lymph node sampling, followed by vincristine and actinomycin B (STAGE 1-2)
Stage 3: additional doxorubicin and radiation therapy

Neoadjuvant three drug therapy and then nephron sparing surgery if possible

Above hepatic veins—neoadjuvant chemotherapy

Management is now response-based to avoid pulmonary radiation

Additional reading resources:

http://bit.ly/2DUIc3M
http://bit.ly/36cf9F4
Link to full length podcast on Wilms Tumor: http://bit.ly/2Rt6UjS

Intro and outro tracks are adapted from "I dunno" by grapes, featuring J Lang, Morusque. Artist URL: http://bit.ly/38oiDGq