Retroperitoneal rhabdomyosarcoma in children. Results of multimodality therapy.

The clinical course of 18 consecutive children treated for primary retroperitoneal rhabdomyosarcoma was reviewed. At diagnosis, 8 patients had regional unresected tumor and 10 patients had disseminated tumor, including 3 patients with documented bone marrow infiltration by tumor. Following combined modality therapy, 14 of 18 patients achieved a greater than 50% tumor response (11 complete and 3 partial responses); 4 patients failed to respond and died of progressive disease within eight months of diagnosis. Among the 14 patients responding, 7 patients had subsequent reextension of active tumor three to 16 months (median, 9 months) following the onset of therapy. Three of the 7 remaining patients died of treatment complications, 2 of intestinal obstruction and 1 of disseminated histoplasmosis, within the first year of therapy and at post-mortem examination had no demonstrable tumor. Four patients are alive and free of active tumor for 10+, 10+, 32+ and 33+ months from diagnosis. Treatment complications have included hematopoietic depression, mucositis, enteritis, intestinal obstruction, excessive weight loss, malnutrition, and life-threatening infection. These results illustrate limitations in current combined modality therapy of retroperitoneal rhabdomyosarcoma and the necessity for future treatment modifications to both reduce morbidity and to improve survival.