Your child's tumor will be staged using the National Wilms' Tumor Study Group (NWTS) staging system, which employs Roman numerals I through V (one through five). Once the tumor has been staged, your child's doctor will create a treatment plan to most effectively treat the disease.
In Stage I tumors with favorable or unfavorable histology, the cancer is limited to the kidney and has been completely removed by surgery, which is followed by a course of chemotherapy. Approximately 40 percent of Wilms' tumors are classified as Stage I tumors.
In Stage II tumors with favorable histology, the cancer has spread to the areas surrounding the kidney and has been completely removed by surgery, which is followed by a course of chemotherapy. Stage II tumors with unfavorable histology usually require surgery followed by radiation therapy and chemotherapy. Approximately 23 percent of all Wilms' tumors are classified as Stage II tumors.
In Stage III tumors with favorable or unfavorable histology, the cancer has spread by direct local extension to the areas surrounding the kidney, including blood vessels, lymph nodes, or other organs near the kidney, and could not be completely removed by surgery, requiring radiation therapy and chemotherapy in addition to surgery. Sometimes Stage III tumors are either too large, too fragile, or are located too close to essential internal organs to be safely removed by surgery. In this case, chemotherapy is used to shrink the tumor to a small enough size that it can be surgically removed later. Approximately 23 percent of all Wilms' tumors are classified as Stage III tumors.
In Stage IV tumors with favorable histology, the cancer has spread beyond the kidney's vicinity into such organs as the lungs, liver, bone, and brain. Stage IV tumors with favorable or unfavorable histology are treated with a combination of surgery, radiation therapy, and chemotherapy. Approximately ten percent of all Wilms' tumors are classified as Stage IV tumors.
Stage V tumors involve tumors found in both kidneys, in which case each kidney is staged separately. Approximately five percent of all Wilms' tumors are classified as Stage V tumors.
