Prognostic factors in 951 nonmetastatic rhabdomyosarcoma in children: a report from the International Rhabdomyosarcoma Workshop.

A total of 951 newly diagnosed patients with nonmetastatic rhabdomyosarcoma (RMS) under 21 years of age from four different cooperative study groups were analyzed to identify the most important pretreatment tumor characteristics in predicting survival. The patient characteristics considered were tumor invasiveness (T), tumor size, status of locoregional lymph nodes, and primary site. The cooperative groups and studies analyzed were: SIOP [RMS-75 (1975-1984)], the Intergroup Rhabdomyosarcoma Study [IRS-II (1978-1982)], Federal Republic of Germany [CWS-81 (1981-1986)] and Italy [RMS-79 (1979-1986), each study involving a different therapeutic protocol. Patient characteristics identified as having a significant relationship to survival by univariate analysis were (favorable features given in brackets): tumor invasiveness [T1], tumor size [less than or equal to 5 cm], status of locoregional lymph nodes [clinically negative], and primary site [orbit and genitourinary non-bladder prostate (GU-non-BP) sites]. T2 tumors tended to have large size (greater than 5 cm), to be associated with positive nodes, and to have a different distribution by primary site than T1 tumors. A multivariate Cox regression analysis of the pooled data identified tumor invasiveness (T), primary site, and the interaction between T and primary site as significant predictive factors for survival. The prognosis of orbital tumors was consistently favorable regardless of T status, whereas the prognosis for "other sites" was consistently unfavorable. International cooperation in this study has permitted the identification of good and poor risk patient subgroups, permitting the focusing of therapeutic protocols to particular risk groups and setting the stage for common future therapeutic protocols for rare subgroups of patients.