Impact of local control and surgical lymph node evaluation in localized paratesticular rhabdomyosarcoma: A report from the Children's Oncology Group Soft Tissue Sarcoma Committee.

Paratesticular rhabdomyosarcoma (PT-RMS) carries a favorable prognosis, but questions persist regarding optimal management. Our goal was to determine the importance of primary tumor resection and surgical assessment of retroperitoneal lymph nodes during staging in patients with PT-RMS. We analyzed patients with localized PT-RMS enrolled onto one of four Children's Oncology Group studies (D9602, ARST0331, D9803 or ARST0531). Surgical resection of the primary tumor prior to chemotherapy and radiotherapy was encouraged when possible with retroperitoneal lymph node dissection (RPLND) recommended for patients ≥10 years of age. Among 279 patients (median 8.1 years old), most tumors were resected with negative margins (78.5%) and most patients did not have radiographic enlargement of regional lymph nodes (90.3%). In patients older than 10 years, imaging alone will miss over 51.5% of nodal disease. Five-year event-free survival (EFS) was 92.0% (95% CI 88.4%-95.6%). Sampling ≥7 to 12 retroperitoneal lymph nodes appeared optimal for detecting positive nodes; while there was a trend toward improved EFS among those undergoing template RPLND, this was not statistically significant (P = .068). Age (P = .28), N-stage (P = .39), T-stage (P = .11) and pathologic node involvement (P = .53) were not associated with overall survival. However, older age and larger tumor size had an additive impact on EFS (P = .027) though not overall survival (P = .13). In conclusion, outcomes for patients with PT-RMS are excellent. Reliance on imaging to detect nodal involvement will miss pathologic node involvement and may result in undertreatment. Surgical nodal staging requires at least 7 to 12 nodes to accurately identify patients with regional nodal disease.