Intensification of therapy for most patients in IRS-III, using a risk-based study design, significantly improved treatment outcome overall. The largest gain from this strategy was realized in patients with gross residual tumor after biopsy (clinical group III). It was also possible to decrease therapy for selected patient subsets without compromising survival.

The results of treatment of 686, previously untreated patients younger than 21 years with rhabdomyosarcoma or undifferentiated sarcoma, who were entered on Intergroup Rhabdomyosarcoma Study-I (IRS-I) were analyzed after a minimum potential follow-up time of 7 years. Patients in Clinical Group I (localized disease, completely resected) were randomized to receive either vincristine, dactinomycin, and cyclophosphamide (VAC) or VAC + radiation. At 5 years, approximately 80% of patients given either treatment were still disease-free and there was no significant difference between treatments in the overall percentages of patients surviving of 93% and 81%, respectively (P = 0.67). Patients in Clinical Group II (regional disease, grossly resected) were randomized to receive either vincristine and dactinomycin (VA) + radiation or VAC + radiation. At 5 years, 72% and 65% of the patients, respectively, were disease-free and there was no evidence of a difference between treatments (P = 0.46). The overall survival percentage at 5 years was approximately 72% for both treatments. Patients in Clinical Groups III (gross residual disease after surgery) and IV (metastatic disease) were randomized to receive either "pulse" VAC + radiation or "pulse" VAC + Adriamycin (doxorubicin) + radiation. The complete remission (CR) rate was 69% in Clinical Group III and 50% in IV, with no statistically significant difference in CR rates between treatments in either group. Those who achieved a CR had a nearly 60% chance of staying in remission for 5 years in Clinical Group III compared with approximately 30% in Clinical Group IV. The overall survival percentage at 5 years was 52% in Clinical Group III compared to 20% in Clinical Group IV (P less than 0.0001). The 5-year survival percentage for the entire cohort of 686 patients was 55%. Survival after relapse was poor, being 32% at 1 year and 17% at 2 years. The risk of distant metastasis was much greater than the risk of local recurrence within each clinical group, and there was no evidence of differing types of relapses between treatments. Primary tumors of the orbit and genitourinary tract carried the best prognosis, whereas tumors of the retroperitoneum had the worst prognosis. The authors conclude that for the therapeutic regimens evaluated there was no therapeutic advantage to including radiation in the treatment of Clinical Group I disease, or cyclophosphamide given as a daily low-dose oral regimen in the treatment of Clinical Group II disease or Adriamycin in the treatment of Clinical Groups III and IV diseases.

Background. Intergroup Rhabdomyosarcoma Study (IRS)‐II, (1978–1984) had the general goals of improving the survival and treatment of children with rhabdomyosarcoma (RMS). Methods. Nine hundred ninety‐nine previously untreated eligible patients entered the study after surgery and were randomized or assigned to therapy by IRS Clinical Group (I‐IV), tumor site, and histologic type. Outcomes were compared between treatments and with results of IRS‐I (1972–1978). Results. Patients in Group I, excluding extremity alveolar (EA) RMS, were randomized to standard vincristine (V), dactinomycin (A), and cyclophosphamide (C) or standard VA. At 5 years, disease‐free survival (DFS) and survival (S) rates were similar between VAC and VA (DFS:80%, 70%, P = 0.47; S:85%, 84%, P = 0.73). Patients in Group II, excluding EA RMS, received radiation and were randomized to intensive VA or repetitive‐pulse VAC. Outcomes were similar for rates of DFS (69%, 74%, P = 0.83) and S (88%, 79%, P = 0.17). Patients in Group III, excluding certain pelvic tumors, received radiation and were randomized to repetitive‐pulse VAC or repetitivepulse VAdrC‐VAC (Adr, Adriamycin [doxorubicin]). Complete remission (CR) rates were close at 74%, 78%, respectively (P = 0.32), as were percentages in CR (73%) and S (66%) rates; the latter outcomes were significantly better than IRS‐I (CR: 56%, P < 0.001; S:50%, P < 0.001). Central nervous system prophylaxis for Group III patients with cranial parameningeal sarcoma increased S rate to 67% from 45% in IRS‐I (P < 0.001). Patients in Group IV received the same regimens as Group III; the CR rate was 53%, 38% remained in CR and S rate was 27% with and 26% without Adr (P = 0.90). At 5 years, S rate for IRS‐II, including EA and all pelvic tumors, was 63%: an 8% increase over IRS‐I (P < 0.001). Outcomes by primary site were as good as, or better than, the IRS‐I experience. Conclusions. Combining all Groups and treatments in IRS‐II, the major improvement in S rate at 5 years between studies was in nonmetastatic patients (71% for IRS‐II versus 63% for IRS‐I, P = 0.01).

Within the context of the epipodophyllotoxin cumulative dose range and schedules of administration encompassed by the monitoring plan regimens, and within the context of multiagent chemotherapy regimens that include alkylating agents, doxorubicin, and other agents, factors other than epipodophyllotoxin cumulative dose seem to be of primary importance in determining the risk of secondary leukemia. Data obtained by the CTEP secondary leukemia monitoring plan support the relative safety of using epipodophyllotoxins according to the therapeutic plans outlined in the monitored protocols.