Abstract
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).