Paratesticular rhabdomyosarcoma in children and adolescents-Outcome and patterns of relapse when utilizing a nonsurgical strategy for lymph node staging: Report from the International Society of Paediatric Oncology (SIOP) Malignant Mesenchymal Tumour 89 and 95 studies.

Purpose: To report the results from International Society of Pediatric Oncology (SIOP) Malignant Mesenchymal Tumors studies (MMT 89 and 95) of males with nonmetastatic paratesticular rhabdomyosarcoma.

Methods: From 1989 to 2003, 159 patients were included. Radical inguinal orchidectomy was recommended, but retroperitoneal lymph node (LN) assessment was based on imaging alone. The treatment was stratified by stage (SIOP tumor-node-metastasis staging system) and histology.

Results: Median age at presentation was 5.6 years (range 0.3-17.6) and 120 patients were of <10 years (75%). Patients ≥10 years had tumors of >5 cm more frequently compared to patients of <10 years (54% vs. 22%, P = 0.0004). The 5- year overall and progression-free survivals were 94% and 83%, respectively. Seventy-eight percent of relapses occurred in the retroperitoneal LN. Thirty-one percent of stage N0 patients of age ≥10 years developed node relapse, compared with 8% of N0 patients aged <10 years (P = 0.0005).

Conclusions: Older patients with paratesticular rhabdomyosarcoma have a significant risk of LN relapse. These results support a surgical approach to LN staging in this subgroup of patients.