Extremity sites

A pooled analysis of 642 patients from four international cooperative groups in Europe and North America was performed to identify prognostic factors in patients with localized extremity rhabdomyosarcoma. Regional lymph node involvement was approximately 2.5 times higher with alveolar rhabdomyosarcoma than with embryonal rhabdomyosarcoma. The 5-year OS rate was 67%. Multivariate analysis showed that decreased OS was correlated with age older than 3 years, T2 invasive disease and N1 nodal status, incomplete initial surgery, treatment before 1995, and treatment by European groups. This analysis also suggested that duration of chemotherapy might have an impact on outcome in these patients.[87]

Primary re-excision before initiation of chemotherapy (i.e., not delayed) may be appropriate in patients whose initial surgical procedure leaves microscopic residual disease that is deemed resectable by a second procedure without loss of cosmesis or function.[5] Chemotherapy or delayed primary excision does not improve outcome over chemotherapy and RT.[8]

Delayed primary excision has been studied in patients with extremity tumors enrolled in the COG intermediate-risk rhabdomyosarcoma trials. Two COG studies (D9803 and ARST0531 [NCT00354835]) were pooled to assess the benefit of delayed primary excision. In the D9803 study, local control with RT after a partial or complete excision was completed at week 12. In the ARST0531 study, RT was done upfront at week 4. Patients with bladder or prostate rhabdomyosarcoma who received a delayed primary excision had no difference in survival, whereas patients with extremity rhabdomyosarcoma had an improved OS with delayed primary excision. The delayed primary excision strategy with a reduction in RT dose resulted in superior OS for those sites.[8,10] Delayed primary excision may be most appropriate for infants because the late effects of RT are more severe than in older patients; thus, even a moderate reduction in radiation dose is desirable. For more information, see the Surgery (Local Control Management) section.

IMRT can be used to spare the bone yet provide optimal soft tissue coverage in extremity rhabdomyosarcoma. Complete primary tumor removal from the hand or foot is not feasible in most cases because of functional impairment.[88][Level of evidence C1] For children presenting with a primary tumor of the hands or feet, COG studies have shown a 10-year local control rate of 100% using RT along with chemotherapy, avoiding amputation in these children.[89][Level of evidence C1] Definitive RT and chemotherapy for Group III tumors resulted in a local control rate of 90% to 95% in the IRS-IV trial.[38]