Improved survival for children with anaplastic Wilms' tumors

The role of imaging in renal and extra-renal rhabdoid tumours

Rhabdoid tumour of the kidney is an uncommon malignancy with a poor prognosis that usually occurs in childhood. Certain imaging features may help distinguish this lesion from the much more common Wilms' tumour. Extra-renal rhabdoid tumours appear to have no specific imaging characteristics.

Wilms' tumor: long-term results from a single institution

One-hundred-twelve children with pathological diagnosis of Wilms' tumor were treated during the period 1979-1989. They were postoperatively staged as follows: stage I, 25 patients; stage II, 27 patients; stage III, 48 patients; and stage IV, 9 patients. Three patients were preoperatively classified as stage V. The National Wilms' Tumor Study (NWTS) staging system was used. Except for Stage V patients, the treatment regimen consisted of nephrectomy followed by radiotherapy and/or chemotherapy according to stage of disease and pathology. Stage I, II, and III patients with favorable histology enjoyed 94 +/- 6%, 86 +/- 8%, and 71 +/- 8% 10-year actuarial survival, respectively. Stage IV patients and those in stages I, II, and III with unfavorable histology had a 10-year actuarial survival of 36 +/- 8%. Univariate analyses proved that NWTS stages affected the 10-year actuarial disease-free survival rates but not the overall survival rates. The histopathology significantly affected the disease-free survival and the overall survival rates both in the whole group of patients and in each stage when considered separately. The same histopathology also affected the incidence of development of distant relapse but not the local recurrence rate. On the other hand, massive tumor rupture at surgery increased the incidence of local relapse but not of distant metastasis and did not affect the overall survival rates. The presence of residuum after surgery had nearly the same effect as tumor rupture on the local recurrence. It also did not increase significantly the distant relapse incidence, but it affected significantly the overall survival. Retroperitoneal lymph node involvement had a similar effect. It increased the incidence of local relapse and decreased the 10-year overall survival rate but it had a borderline effect on development of distant metastasis (P = 0.06). The age at diagnosis had also a borderline effect on disease-free survival but it had not effect, of statistical significance, on the overall survival.

Recent experience with Wilms' tumor: 1978-1991

BACKGROUND

The treatment of Wilms' tumor has undergone major advances in the past four decades. Current therapy is based on both the stage and pathology of the tumor. We have reviewed our recent experience with this tumor to assess the results of treatment on protocols that generally avoid the use of doxorubicin.

METHODS

Between January 1978 and December 1991 we treated 114 children with renal tumors. Ninety-one (80%) had favorable histology Wilms' tumor and 23 (20%), unfavorable histology tumors (13 anaplastic Wilms' tumors, four clear cell tumors of the kidney, and six sarcomatous tumors with rhabdoid elements). Chemotherapy was divided into two eras: 1978-1982 (vincristine and actinomycin-D) and 1983-1991 [vincristine and actinomycin-D for all patients, and cyclophosphamide for those with favorable histology and metastatic disease (n = 13) and all patients with anaplastic histology (n = 13)]. Four patients with clear cell or rhabdoid/sarcomatous tumor, three of whom are disease-free, were treated with a five-drug regimen (vincristine, doxorubin, cyclophosphamide, platinum, and VP-16). Approximately two thirds of the patients received megavoltage radiotherapy to the tumor bed. Mean abdominal radiation doses from 1978 to 1982 were slightly higher than those used from 1983 to 1991 (2,597 +/- 782 cGy vs. 2,039 +/- 524 cGy, respectively).

RESULTS

No isolated local failures were observed in any favorable histology patient who received radiotherapy. Among the 91 patients with favorable histology, there was no statistically significant difference in event-free survival irrespective of stage. Outcome for patients with anaplastic or clear cell variants was not different from that for those patients with favorable histology, but there were only small numbers in these groups for comparison. Only children with a rhabdoid/sarcomatous variant demonstrated survival that was different from all others (p = 0.00). Our previously reported patients with stage I tumors (< 550 g) (n = 11) who were treated by nephrectomy only continue to have an excellent outcome (survival 100%).

CONCLUSIONS

Wilms' tumors remain highly curable. Some unfavorable histology tumors require intensive therapy. Others such as our stage I tumors may be best observed without adjuvant therapy to avoid the toxicity of treatment.