Previously Untreated Childhood Rhabdomyosarcoma
Table 5. Radiation Therapy (RT) Dose According to Rhabdomyosarcoma Group, Histology, and Site of Disease (Children's Oncology Group [COG]) continued...
In patients who have been treated with chemotherapy and RT for rhabdomyosarcoma arising in the bladder/prostate region, the presence of well-differentiated rhabdomyoblasts in surgical specimens or biopsies obtained after treatment does not appear to be associated with a high risk of recurrence and is not an indication for a major surgical procedure such as total cystectomy.[89,92,93] One study suggested that in patients with residual bladder tumors with histologic evidence of maturation, additional courses of chemotherapy should be given before cystectomy is considered. Surgery should be considered only if malignant tumor cells do not disappear over time following initial chemotherapy and RT. Because of very limited data, it is unclear whether this situation is analogous for patients with rhabdomyosarcoma arising in other parts of the body.
The kidney is occasionally the primary site for rhabdomyosarcoma; six cases were identified from among 5,746 eligible patients enrolled on IRSG protocols. The tumors were large (mean widest diameter, 12.7 cm), and anaplasia was present in four (67%) patients. Three patients with grossly complete tumor removal at diagnosis survived; the three with incomplete removal and gross or metastatic disease died of infection or metastatic tumor.
For patients with genitourinary primary tumors of the vulva/vagina/uterus, the initial surgical procedure is usually a vulvar or transvaginal biopsy. Initial radical surgery is not indicated for rhabdomyosarcoma of the vulva/vagina/uterus. Conservative surgical intervention for vaginal rhabdomyosarcoma, with primary chemotherapy and adjunctive radiation (often brachytherapy) for residual disease (Group II or III), results in excellent disease-free survival.[95,96]
In the COG-ARST0331 study, there was an unacceptably high rate of local recurrences in girls with Group III vaginal tumors who did not receive RT.[Level of evidence: 3iiiDiii] Therefore, the COG-STS recommends that RT be administered to patients with residual viable vaginal tumor, beginning at week 24.
Because of the smaller number of patients with uterine rhabdomyosarcoma, it is difficult to make a definitive treatment decision, but chemotherapy with or without RT is also effective.[95,97] Twelve of 14 girls with primary cervical embryonal (mainly botryoid) rhabdomyosarcoma were disease-free following VAC (vincristine, dactinomycin, and cyclophosphamide) chemotherapy and conservative surgery. Of note, two girls also had a pleuropulmonary blastoma and another had Sertoli-Leydig cell tumor. Exenteration is usually not required for primary tumors at these sites, but if needed, it may be done, with rectal preservation possible in most cases.