Table 5. Radiation Therapy (RT) Dose According to Rhabdomyosarcoma Group, Histology, and Site of Disease (Children's Oncology Group [COG]) continued...
Because of the significant incidence of regional nodal spread in patients with extremity primary tumors (often without clinical evidence of involvement) and because of the prognostic and therapeutic implications of nodal involvement, extensive pretreatment assessment of regional (and possibly in-transit) nodes is warranted.[59,63,64,65,66]; [Level of evidence: 3iiDi] In-transit nodes are defined as epitrochlear and brachial for upper-extremity tumors and popliteal for lower-extremity tumors. Regional lymph nodes for those tumor sites are axillary/infraclavicular nodes and inguinal/femoral nodes, respectively. In a review of 226 patients with primary extremity rhabdomyosarcoma, 5% had tumor-involved in-transit nodes, and over 5 years, the rate of in-transit node recurrence was 12%. Very few patients (n = 11) underwent in-transit node examination at diagnosis, but five of them, all with alveolar rhabdomyosarcoma, had tumor-involved nodes. However, the EFS rates were not significantly different among those evaluated initially and those not evaluated initially for in-transit nodal disease.
The surgical management of patients with lesions of the chest wall or abdominal wall should follow the same guidelines as those used for lesions of the extremities (i.e., wide local excision and an attempt to achieve negative microscopic margins). These resections may require use of prosthetic materials. Very large truncal masses should be biopsied initially. Chemotherapy, with or without RT, is then given. Initial surgery is performed if there is a realistic expectation of achieving negative margins. However, most patients who present with large tumors in these sites have localized disease that becomes amenable to complete resection with negative margins after preoperative chemoradiotherapy and those patients may have excellent long-term survival.[68,69,70,71]
Intrathoracic or intra-abdominal sarcomas may not be resectable at diagnosis because of the massive size of the tumor and extension into vital organs or vessels. For patients with initially unresectable retroperitoneal/pelvic tumors, complete surgical removal following chemotherapy, with or without RT, offers a significant survival advantage (73% vs. 34%–44% without removal). The International Society of Pediatric Oncology Malignant Mesenchymal Tumor (SIOP-MMT) group found that RT improved local control in patients with localized pelvic rhabdomyosarcoma whose initial surgical procedure was biopsy only, leaving macroscopic residual tumor. Age older than 10 years and lymph node involvement were unfavorable prognostic factors.[Level of evidence: 2A]
With rhabdomyosarcoma of the biliary tree, total resection is rarely feasible and standard treatment includes chemotherapy and RT. Outcome for patients with this primary site is good despite residual disease after surgery. External biliary drains significantly increase the risk of postoperative infectious complications. Thus, external biliary drainage is not warranted.
Patients with rhabdomyosarcoma arising from tissue around the perineum or anus usually have advanced disease. These patients have a high likelihood of regional lymph node involvement, and about half of the tumors have alveolar histology. The current recommendation is to sample the regional lymph nodes. When feasible and without unacceptable morbidity, removing all gross tumor prior to chemotherapy improves the likelihood of cure. In Intergroup Rhabdomyosarcoma Study Group (IRSG) Protocols I through IV, the OS rate after aggressive therapy for 71 patients with tumors in this location was 49%, best for patients in Stage 2 (small tumors, negative regional nodes), intermediate for those in Stage 3, and worst for those in Stage 4 at diagnosis. However, with the goal of organ preservation, patients with tumors of the perineum/anus are preferentially managed with chemotherapy and RT without aggressive surgery, which may result in loss of sphincter control.