WILMS’ TUMOR

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Wilms’ tumor, also known as nephroblastoma, stands as the most prevalent kidney cancer seen in children. Typically, it manifests as a tumor in one kidney, though around 5% of cases involve tumors in both kidneys.

The occurrence of this tumor primarily targets children aged 3 to 4 years, tapering significantly beyond the age of 5. Fortunately, advancements in medical understanding and treatment have significantly improved the prognosis, with many children undergoing successful recoveries.

Causes of Wilms’ tumor

The root cause of the tumor lies in the abnormal growth of kidney cells, resulting in the formation of cancerous cells. This irregular growth stems from random genetic mutations, although in rare cases, it can be attributed to inherited gene alterations passed down from parents.

Types

1. Favorable histology: This category encompasses over 90% of Wilms tumors, indicating minimal variation among cancer cells. Children with this type typically have a favourable prognosis and a high likelihood of cure.
2. Unfavorable or anaplastic histology: In this type, cancer cells display a range of abnormalities under the microscope. It poses greater challenges for treatment and cure compared to favourable histology tumors.

Symptoms

Symptoms can vary; some children may not exhibit any noticeable signs, while others may experience:

• Abdominal pain
• Abdominal swelling
• Palpable abdominal mass
• Fever
• Nausea
• Loss of appetite
• Hypertension (high blood pressure)
• Hematuria (blood in urine)
• Constipation
• Shortness of breath

Often, Wilms tumors grow to a substantial size before becoming evident, sometimes serving as the sole indicator of the disease. On average, these tumors weigh around 1 pound.

Risk factors of Wilms tumor

Several factors can increase the likelihood of a child developing a this type of tumor:

1. Age: Most cases of Wilms tumor occur in children aged between 3 and 5 years old.
2. Gender: Girls have a higher predisposition to Wilms tumor compared to boys.
3. Race: Black children have a slightly elevated risk of developing Wilms tumor compared to children of other racial backgrounds.
4. Family history: If a family member has had a Wilms tumor, the chances increase for a child within the family to develop it as well.
5. Birth defects: Certain birth defects may also elevate the risk, including:
   • Cryptorchidism (undescended testicles)
   • Hypospadias (abnormal placement of the urethral opening)
   • Aniridia (partial or total absence of the iris)
   • Hemihypertrophy (asymmetrical growth of limbs)
6. Other health conditions: Wilms tumor may occur in children with rare syndromes like:
   • WAGR syndrome, which affects the urinary tract
   • Denys-Drash syndrome, characterized by male genitalia along with female traits
   • Microcephaly, involving abnormally small head size at birth
   • Beckwith-Wiedemann syndrome leads to enlarged internal organs.

Diagnosis of Wilms tumor

Diagnosing this tumor typically involves several steps during your child’s medical assessment:

1. Physical exam and medical history: The doctor will inquire about symptoms and any relevant family history of cancer or urinary tract issues.
2. Blood test: This assesses kidney and liver function, as well as red and white blood cell counts and blood clotting factors.
3. Urine test: Conducted to detect the presence of blood in the urine.
4. Imaging tests: These may include ultrasound, MRI, or CT scans of the abdomen to visualize the kidney and surrounding structures.

If a tumor is identified in your child’s kidney, additional steps may include:

• Biopsy: taking a small tissue sample for microscopic examination to confirm the presence of cancerous cells.
• Further imaging tests: These help determine the extent of the disease and whether it has spread.
• Bone scan: used to detect any cancerous involvement of the bones.

Stages of the Wilms tumor

Wilms tumor staging is crucial in understanding the disease progression. The stages of the tumor are classified as follows:

1. Stage I: Cancer is confined to one kidney, and surgical removal can eliminate it entirely.
2. Stage II: Cancer has spread into the vicinity around the kidney but can still be completely removed via surgery.
3. Stage III: Cancer hasn’t extended beyond the abdomen, but complete surgical removal is not feasible.
4. Stage IV: Cancer has metastasized to distant sites like the lungs, bones, brain, or lymph nodes outside the abdomen.
5. Stage V: Tumors are present in both kidneys.

Treatments for Wilms tumor

Treating of the tumor involves a combination of therapies tailored to the extent of cancer spread, typically including surgery, chemotherapy, and radiation therapy.

1. Surgery:
   • Partial nephrectomy: This procedure removes the tumor along with some surrounding healthy tissue.
   • Radical nephrectomy: In more advanced cases, the affected kidney, ureter, adrenal gland, and nearby tissue are removed.
   • Removal of both kidneys: In rare instances, both kidneys may need to be removed, necessitating dialysis until a kidney transplant becomes feasible.
2. Chemotherapy:
   • Medications are administered to combat cancer cells throughout the body. Most Wilms tumor patients receive chemotherapy at some stage, although it may induce side effects such as hair loss, fatigue, mouth sores, nausea, and increased susceptibility to infection. However, medical teams can effectively manage these side effects.
3. Radiation therapy:
   • Intense radiation targets cancer cells directly. It’s typically employed for stage III and above tumors. Despite its efficacy, radiation therapy can cause short-term and long-term side effects, including tissue damage. Hence, doctors aim to use the lowest effective dose.

Outlook:

• The prognosis for most children with Wilms tumor is optimistic. Up to 90% of cases with favorable histology tumors can be cured. However, if the tumor presents unfavorable histology, the cure rate diminishes.
• Following cancer treatment, regular medical follow-ups are essential to monitor the child’s health and ensure any potential recurrence is promptly addressed.

It’s crucial to maintain open communication with your medical team, asking questions whenever uncertainty arises. This enables you to provide optimal support for your child throughout their treatment journey.

Sources:

• Mayo Clinic: “Wilms’ Tumor.”
• American Cancer Society: “What is Cancer?” “What is Wilms’ Tumor?”
• Kids Health from Nemours: “Wilms Tumor.”
• Memorial Sloan Kettering Cancer Center: “About Wilms’ Tumor.”
• CureSearch for Children’s Cancer: “Wilms Tumor in Children – In Treatment.”
• St. Jude Children’s Research Hospital: “Wilms Tumor.”
• The University of Texas M.D. Anderson Cancer Center: “Wilms’ Tumor Symptoms.”
• Cancer.net/American Society of Clinical Oncology: “Childhood Cancer: Questions to Ask the Doctor.”
• Cancer Research UK: “Wilms’ Tumour (Kidney Cancer in Children).”
• American Society of Clinical Oncology: “Wilms Tumor – Childhood.”