Purpose: Our purpose was to assess disease outcomes and late toxicities in pediatric patients with rhabdomyosarcoma treated with conformal photon radiation therapy (RT). Methods and Materials: Sixty-eight patients (median age, 6.9 years) were treated with conformal photon RT to the primary site on a prospective clinical trial. Target volumes included a 1-cm expansion encompassing microscopic disease. Prescribed doses were 36 Gy to this target volume and 50.4 Gy to gross residual disease. Chemotherapy consisted of vincristine/dactinomycin (n = 6), vincristine/dactinomycin/cyclophosphamide (n = 37), or vincristine/dactinomycin/cyclophosphamide-based combinations (n = 25). Patients were evaluated with primary-site magnetic resonance imaging, whole-body [18F]fluorodeoxyglucose positron emission tomography, and chest computed tomography for 5 years after treatment. Results: Five-year disease-free survival was 88% for low-risk (n = 8), 76% for intermediate-risk (n = 37), and 36% for high-risk (n = 23) patients (P ≤ .01 for low risk/intermediate risk vs high risk). The cumulative incidence of local failure (LF) at 5 years for the entire cohort was 10.4%. Tumor size at diagnosis was a significant predictor of LF (P < .01). Patients with head and neck primary tumors (n = 31) had a 35% cumulative incidence of cataracts; the risk correlated with lens dose (P = .0025). Jaw dysfunction was more severe when the pterygoid and masseter muscles received a mean dose of >20 Gy (P = .013). Orbital hypoplasia developed more frequently after a mean bony orbit dose of >30 Gy (P = .041). Late toxicity in patients with genitourinary tumors included microscopic hematuria (9 of 14), bladder-wall thickening (10 of 14), and vaginal stenosis (2 of 5). Conclusions: Long-term LF rates were low, and higher rates correlated with larger tumors. Treatment-related toxicities resulting in measurable functional deficits were not infrequent, despite the conformal RT approach.
|Number of pages||9|
|Journal||International Journal of Radiation Oncology Biology Physics|
|State||Published - May 1 2020|
Bibliographical noteFunding Information:
This work was supported in part by the American Lebanese Syrian Associated Charities (ALSAC), the National Cancer Institute at the National Institutes of Health (P30 CA021765, St. Jude Cancer Center Support Grant), and the Lance Armstrong Foundation to M.J.K.
© 2020 Elsevier Inc.
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging
- Cancer Research