By Stella Irungu, Ph.D.
Wilms tumour (WT), also known as nephroblastoma, is the most common kidney cancer in children, usually diagnosed between ages 3 to 5 years. It remains the most common solid paediatric tumour in Africa, exceeding 10% of total paediatric cancers in many countries (Kenya 16%, Rwanda 21.3%, Senegal 22%, Ivory Coast 14.5%, Mali 17.6%, and Congo 15.5%). Children with black ancestry have a higher likelihood of developing WT, and this persists despite geographic locations and generations of genetic distance from sub-Saharan origin.
WT is often curable for children in high-income nations in contrast to children in Sub-Saharan Africa’s resource-constrained regions who experience poor outcomes. In Kenya, the 2-year survival rate without disease-related complications is about 34%, compared to over 90% in high-income countries. While WT is often not inherited, there are some genetic reasons for tumour development. Some children may have mutated (changed), damaged, or missing genes crucial for normal kidney development. These genes are also responsible for causing several congenital disabilities, including Denys-Drash Syndrome, which is characterised by abnormal development of male genital organs. Children with Denys-Drash Syndrome have a 90% chance of developing WT.
WT mainly occurs in one kidney. However, approximately 5-7% of all WT patients will have tumours on both kidneys. Patients with these bilateral WT are diagnosed at a younger agen (less than one year) and often have precursor lesions called nephrogenic rests (clusters of undifferentiated embryonic kidney cells). The typical presentation of this tumour is an enlarged swelling usually observed on one side of the abdomen. This may be accompanied by pain, blood in urine, high blood pressure, anaemia, and fever. Blood and urine tests and imaging follow this to confirm the presence of the tumour and determine whether it has spread to other organs.
WT management involves surgical removal of the affected kidney or tumour. The entire organ is removed when the tumour occurs in just one kidney. This surgical procedure is known as total nephrectomy. However, with bilateral WT, removing both kidneys would eliminate renal function. Instead, patients first need chemotherapy to shrink the tumors as much as possible, followed by organ-sparing surgery, also known as partial nephrectomy, to remove the tumours without removing the whole kidney. A pathologist will then review the resected tissues to determine the stage of the disease, thus informing treatment. Other tests are also recommended to determine the presence of specific chromosomal changes, which may indicate how well a child will respond to chemotherapy.
Early diagnosis is very crucial for effective treatment and prognosis of any disease. In high-income countries, over 80% of childhood cancers are cured due to the availability of comprehensive services. However, the cure rate in lower- and middle-income countries is less than 30%. Death often results from factors such as lack of diagnosis, delayed diagnosis, treatment abandonment, adverse effects of drug toxicity, and disease relapse.
Addressing these challenges is crucial for improving outcomes in resource-constrained regions. Most research on WT has been conducted in Europe and America. It is unclear whether these findings can be applied to African patients due to differences in genetic makeup. Therefore, there is a crucial need to study WT in Sub-Saharan Africa to gain a deeper insight into the unique biology of this cancer in these regions. This is especially important given the presentation of aggressive tumours that respond poorly to treatment.
Further research into therapeutic management would also enhance treatment outcomes for children with early-stage WT, minimising the risk of disease recurrence. Simultaneously, for children diagnosed with unfavourable high-risk forms of WT, the objective is to develop better treatment approaches that significantly improve the likelihood of a favourable outcome. It is thanks to research that we know all this about kidney cancer in children. By further investing in research, we can address the causes and thereby increase the odds of finding and providing a cure for these children.