What is the role of radiotherapy in a newly diagnosed patient with parameningeal rhabdomyosarcoma w/ intracranial extension, a positive CSF but no extra-CNS metastases?

The question as to the role of RT in patients with parameningeal (PM) RMS with CNS leptomeningeal disease is complex and one lacking scientific evidence to support one’s answer. My response represents a historic viewpoint gained from hearing the discussions of the Intergroup Rhabdomyosarcoma Group (IRSG) and Children’s Oncology Group (COG) over the past 5+ decades.

To address this complex issue, one needs to know details of the specific clinical case of interest, including: initial presentation vs time of relapse; extent of disease (local/regional vs hematogenous) spread outside the CNS; and clinical factors including age, symptoms, coexisting illness/disease, ability to tolerate therapy, and goals of treatment (survival, local control, pal...