Objective: Wilms' tumor is a malignant disease in the kidneys that usually affects young children. Information about the clinical behaviour of this tumor in Iceland has been scarce. The aim of this study was to find the incidence, clinical presentation, treatment and survival of patients with Wilms' tumor.
Material and methods: Included in the study were all patients diagnosed with Wilms' tumor in Iceland from 1st of January 1961 to 31st of December 1995. Altogether, there were 17 patients, 15 children, mean age 33 months (standard deviation 19, range 5-77 months) and two adults (age 25 and 29), with M/F ratio 0.7. Information was gained from each patient's record and the cancer registry of the Icelandic Cancer Society. All the tumors were re-evaluated by a pathologist and staged according to the NWTS staging system.
Results: Age adjusted incidence during the study period was 0.2/100,000 per year (1.0 for children under 15 years). Abdominal mass (65%) and abdominal pain (53%) were the most common symptoms. Histology was typical in all cases except one with anaplasia and another with sarcomatous growth. One patient was diagnosed in stage I (6%), six in stage II (35%) and seven in stage III (41 %). Two patients had pulmonary metastases (stage IV) and one had bilateral tumor (stage V). Nephrectomy was performed in all cases. The operative mortality was 12%. Of the 15 patients surviving surgery, 12 received radiotherapy, 12 chemotherapy and nine both treatments. Crude five-year-survival for the whole group was 42%, 25% for the patients diagnosed 1961-1976 and 61% for those diagnosed 1977-1995 (p=0.13). The patient with bilateral tumor was still alive 13 years after diagnosis.
Conclusion: As in other Western countries, Wilms' tumor is rare in Iceland and has similar incidence and clinical presentation. Two thirds of the patients were diagnosed in stage II or III. Even patients with distant metastases can be cured with multimodal treatment: surgery, chemotherapy and radiotherapy. There was a trend toward better survival during the study period.