Trang H La MD, MBA, Presenter: Nothing to Disclose

Suzanne L. Wolden MD, Abstract Co-Author: Nothing to Disclose

David Rodeberg MD, Abstract Co-Author: Nothing to Disclose

Doug Hawkins MD, Abstract Co-Author: Nothing to Disclose

James Anderson PhD, Abstract Co-Author: Nothing to Disclose

Sarah S. Donaldson MD, Abstract Co-Author: Nothing to Disclose

To evaluate the incidence and prognostic factors of regional lymph node involvement (N1) at diagnosis and relapse in children with non-metastatic rhabdomyosarcoma (RMS) of the extremity, with attention to in-transit path of spread.

Intergroup Rhabdomyosarcoma Studies III, IVP, and IV enrolled 226 children with RMS of the extremity. Proximal (axillary/infraclavicular, inguinal/femoral) and in-transit (brachial, epitrochlear, popliteal) lymph node involvement and patterns of regional failure are evaluated. Median follow-up for surviving patients is 10.4 years.

Estimated 5-year overall and event-free survival (EFS) for the entire cohort are 68% and 61%, respectively. Higher disease stage and IRS Group predict for worse EFS (p<0.01). Fifty-five of 226 patients (24%) had clinical or pathological evidence of any regional N1 disease at diagnosis. The estimated 5-year incidence of any regional lymph node relapse is 12%. Prognostic factors predicting regional relapse are: N1 disease at diagnosis and female gender. In the 116 patients with a distal extremity primary tumor beyond the in-transit region, 4% had in-transit and 25% had proximal N1 disease at diagnosis. The estimated 5-year incidence of in-transit failure is 13% versus 8% for a proximal nodal failure. Among the 22 patients who underwent lymph node sampling and/or radiation therapy (RT) to the in-transit region, the in-transit failure is 0%, whereas it is 15% among the 94 patients who did not have nodal staging and/or RT (p=0.07), although 5-year EFS did not differ between the two groups (64% vs. 55%, p=0.47). In-transit failures are more common in children with a lower extremity primary tumor than in those with an upper extremity tumor (18% vs 5%, p=0.04).

The high incidence of regional involvement necessitates aggressive staging and treatment of the draining regional lymph nodes in RMS of the extremity. The in-transit region is as common a site of relapse as the proximal nodal region in patients with distal extremity tumors. At diagnosis, particular attention should be given to in-transit nodal pathways through imaging of the entire affected extremity and potential nodal draining areas with MRI and FDG-PET if available.

To fully evaluate rhabdomyosarcoma patients at diagnosis, imaging of the entire affected extremity and potential nodal draining areas with MRI and FDG-PET, if available, is recommended.

La, T, Wolden, S, Rodeberg, D, Hawkins, D, Anderson, J, Donaldson, S, Patterns of Failure in Rhabdomyosarcoma of the Extremity: A Report from the Children's Oncology Group.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8013474.html