Wilms' tumor, also known as nephroblastoma, is a rare cancer of the kidney mainly affecting children. Wilms' tumor is commonly seen in kids from ages 3 to 4 and tends to occur less frequently after the age of 5. The most common kidney cancer in children is Wilms' tumor. Wilms' tumor commonly develops in only one kidney, however, it can also be found at the same time in both the kidneys. Thanks to the improvement in the diagnosis as well as treatment of Wilms' tumor, the prognosis of this disease has also improved and is mostly good.
Treatment of Wilms' tumor comprises of surgery, chemotherapy and radiation therapy.
Causes of Wilms' Tumor
The exact cause of Wilms' tumor is not clear. Any type of cancer starts when there is any problem in the DNA of the cell. This results in rapid and uncontrollable division of the cells and they continue to live on instead of dying like normal cells. These cells accumulate and form a tumor. In case of Wilms' tumor, the cancer and tumor develop in the kidney cells. Sometimes, the DNA mutations are hereditary and can be passed from parents to children.
Risk Factors for Wilms' Tumor
- Black children are at a slightly increased risk for developing Wilms' tumor than children of other races. Whereas children of Asian descent carry a lower risk for Wilms' tumor
- A family history of Wilms' tumor increases the risk for developing this disease.
- Certain Abnormalities Present in Children at Birth Increase the Risk for Wilms' Tumor such as:
- Aniridia is a condition where the colored region of the eye is partially formed or does not form at all.
- Undescended testicles, is a condition where one or both of the testicles do not descend into the scrotum.
- Hemihypertrophy is a condition where one side of the body is larger than the other side.
- Hypospadias is a condition where the urethral opening, instead of being on the tip of the penis, is present on the underside of the penis.
Wilms' Tumor can be Associated and can Occur as Part of some Rare Syndromes such as:
- Denys-Drash syndrome includes kidney disease, Wilms' tumor, and male pseudohermaphroditism.
- WAGR syndrome consists of aniridia, Wilms' tumor, mental retardation and abnormalities of the urinary system and genitals.
- Beckwith-Wiedemann syndrome includes protrusion of the abdominal organs into the base of the umbilical cord, macroglossia (large tongue) and enlarged internal organs.
Signs & Symptoms of Wilms' Tumor
The child doesn't always exhibit symptoms of Wilms' tumor and may appear healthy. Some of the symptoms experienced by the patient are:
- Swelling in the abdomen.
- Pain in the abdomen.
- Mass in the abdomen which can be felt.
- Hematuria or blood in the urine.
Investigations to Diagnose Wilms' Tumor
- A physical examination is done to look for signs of Wilms' tumor.
- Blood and urine tests are done to assess the child's overall health.
- Imaging tests, such as CT scan and MRI, are done of the patient's kidneys to find out whether there is a tumor present and on which kidney it is present.
- X-ray and CT scan of the chest and bone scan are done to determine the stage of the cancer and to find out if the cancer has metastasized beyond the kidneys to other parts of the body.
- Surgery, where the tumor with the complete kidney can be removed and sent to lab for analysis to determine whether the tumor is cancerous and what type of cells are involved.
Stages of Wilms' Tumor
- Stage I: In this stage, the cancer is present only in one kidney and can often be completely removed with surgery.
- Stage II: In this stage, the cancer has spread beyond the kidney to the adjacent tissues and other structures near the involved kidney. However, surgery can completely remove the cancer.
- Stage III: In this stage, the cancer has metastasized from the kidney to adjacent lymph nodes or other structures present in the abdomen and cannot be completely removed via surgery.
- Stage IV: In this stage, the cancer has metastasized to distant structures like liver, lungs, bones or brain.
- Stage V: In this stage, the cancer is present in both the kidneys.
Treatment for Wilms' Tumor
Treatment for Wilms' tumor depends on the stage of the cancer and comprises of surgery and chemotherapy. It is recommended to seek treatment from an experienced doctor from children's cancer center, as this type of cancer is rare.
Surgery for Wilms' Tumor
Nephrectomy is a surgery done to remove the entire kidney or only a part of the kidney. Surgery can also be done to confirm the diagnosis, as the tissue removed during the surgery is sent for analysis to the laboratory. Surgery for Wilms' tumor comprises of:
- Partial nephrectomy for Wilms' Tumor is a surgical procedure done to remove a part of the affected kidney where the tumor and some part of the healthy kidney tissue surrounding the tumor are removed. Partial nephrectomy is an option if the cancer is very small or if there is only one functioning kidney.
- Radical nephrectomy for Wilms' Tumor is removing the complete kidney which is affected as well as the surrounding tissues, including the adrenal gland and the ureter. The adjacent lymph nodes may also be removed.
- Removal of the entire or part of both the kidneys is done if cancer is present in both the kidneys. In such cases, the surgeon tries to remove as much cancer as he/she can from both the kidneys. If both the kidneys are removed, then the child will have to undergo kidney dialysis. Kidney transplantation is also an option.
Chemotherapy for Wilms' Tumor
Chemotherapy treatment for Wilms' Tumor comprises of using powerful drugs to destroy the cancer cells in the body. A combination of drugs are used which work together in killing the cancer cells. Chemotherapy can be done via a pill form or can be administered intravenously. Common side effects of chemotherapy include: Nausea, vomiting, appetite loss, hair loss and increased frequency of infections. Chemotherapy for Wilms' Tumor can be used before the surgery to help shrink the tumor, so it can be easily removed or it can be done after the surgery to kill any remaining cancer cells in the body. Chemotherapy alone can also be done in children who have advanced stage cancer which cannot be completely removed with the surgery.
Chemotherapy treatment for Wilm's Tumor is administered before surgery in children whose both kidneys are affected with cancer. This increases the likelihood of saving at least one kidney, so that kidney function can be preserved.
Radiation Therapy for Wilms' Tumor
Radiation therapy for Wilm's Tumor comprises of using high-energy beams, like x-rays, to destroy cancer cells. In radiation therapy, the child is made to lie on the table and radiation is given through a large machine which moves around the child, aiming the energy beams at the site of the cancer. Side effects of radiation include nausea, fatigue, diarrhea and skin irritation resembling sunburn. Radiation therapy for Wilm's Tumor can also be used after the surgery to destroy any remaining cancer cells, which were not removed during the surgery. Radiation therapy can also be done to control the cancer which has metastasized to other parts of the body.
In clinical trials, research studies and new treatments are administered to the patient. They do not guarantee a cure; only a chance at the latest cancer treatment. The side effects in clinical trials also cannot be predicted. The risks and benefits of clinical trials should be discussed with the doctor before enrolling the patient in a clinical trial.
Prognosis & Survival Rate for Wilms' Tumor
The prognosis of Wilms' tumor has improved over the last few years and is good because of the improvement in the diagnosis as well as treatment of the Wilms' tumor. Prognosis is based upon the survival rates. There are some parents who want to know the survival statistics and some who do not want to know anything regarding their child's survival rate and then there are some who don't find these statistics helpful at all.
The 4-year survival rate is the percentage of children who go on to live for a minimum of 4 years after the diagnosis of cancer. There are many patients who live for more than 4 years and many are also cured. To arrive at this 4-year survival rates, statistics are taken of children who were treated 4 years ago. Prognosis since then has improved due to improvement in the diagnosis and treatment of Wilms' tumors.
The two most important factors in determining a prognosis of the patients include the stage and histology of the Wilms' tumor. The numbers given below of the survival rates are based on a small number of patients, so they may not be accurate. Survival rates are also calculated based on the previous result of patients with this disease. However, each case is different and it is difficult to predict the course and outcome in each individual's case. As mentioned before, prognosis depends on the stage and histology of a Wilms tumor. Other factors which affect the child's prognosis include the tumor's response to treatment. Please bear this in mind that these survival rates are only rough estimates and the patient's doctor is the best person to tell you if the statistics given below are favorable or not as he/ she knows the patient's case the best.
Wilms Tumor 4-year Survival Rates comprise of:
- In stage I tumor, the 4-year survival rate is, 99% of the patients with favorable histology and 83% of the patients with unfavorable histology.
- In stage II tumor, the 4-year survival rate is, 98% of the patients with favorable histology and 81% of the patients with unfavorable histology.
- In stage III tumor, the 4-year survival rate is, 94% of the patients with favorable histology and 72% of the patients with unfavorable histology.
- In stage IV tumor, the 4-year survival rate is, 86% of the patients with favorable histology and 38% of the patients with unfavorable histology.
- In stage V tumor, the 4-year survival rate is, 87% of the patients with favorable histology and 55% of the patients with unfavorable histology.