The effect of chemotherapy dose intensity on the hematological toxicity of the treatment for Wilms' tumor. A report from the National Wilms' Tumor Study.

Purpose: To determine the relationship between hematological toxicity and actual dose intensity of treatment of patients randomized to therapy during the first 28 months of the National Wilms' Tumor Study-4.

Methods: The mean minimum white blood cell count (WBC), platelet count (PLT), hemoglobin, and absolute neutrophil count (ANC) during the first two courses of chemotherapy and the mean number of days of hospitalization for toxicity were compared between standard and "pulse-intensive" regimens for all randomized patients entered on National Wilms' Tumor Study-4 between August 6, 1986 and December 31, 1988. The mean dose intensity of dactinomycin, vincristine, and doxorubicin received during the first two courses and the entire course of treatment was compared between standard and "pulse-intensive" regimens.

Results: The mean minimum WBC, PLT, and ANC were all significantly lower during the first two courses of chemotherapy for stage I patients treated with the standard regimen, compared with the "pulse-intensive" regimen. The mean dose intensity of dactinomycin and doxorubicin was significantly higher for patients treated with the "pulse-intensive" regimens, compared with the appropriate standard regimen.

Conclusions: The "pulse-intensive" administration schedule for the treatment of children with Wilms' tumor permits administration of chemotherapy at a higher dose intensity without an increase in hematological toxicity.