Case report: Helical tomotherapy-based whole lung irradiation with simultaneous integrated boost for pulmonary...

Ewing's sarcoma (EwS) frequently metastasizes to the lungs. While whole-lung irradiation (WLI) improves survival, conventional techniques carry a risk of cardiac toxicity. Helical Tomotherapy (HT) offers superior target conformity and the ability to deliver a simultaneous integrated boost (SIB) to metastases. This case series evaluates the feasibility and short-term outcomes of HT-based WLI with SIB in patients with pulmonary metastatic EwS, with a focus on the challenges encountered across a variety of complex clinical scenarios.

We report on five patients (3 male, 2 female; age range 15-36 years, mean age 24.2 years) with pulmonary/pleural metastases who received HT-based WLI (12-15 Gy/10 fractions) with SIB to thoracic lesions (27-45 Gy). The cases are unique in their diversity: one patient with 36 bilateral lung metastases achieving complete response (Case 2), one with prior sternal SBRT developing grade 3 radiation pneumonitis (RP) on concurrent immunotherapy (Case 5; thoracic radiotherapy delivered to spatially distinct, non-overlapping target volumes), and one with pleural progression after multiple chemotherapy lines (Case 3). Concurrent therapies included anlotinib (n=4), sintilimab (n=1), or chemotherapy (n=1). With a median follow-up of 5.5 months (range 2-12.5), the overall response rate was 86.7% (59/68 lesions: 53 complete responses, 1 near-CR, 5 partial responses). Median lung/pleural progression-free survival was 5.5 months, with four patients surviving and one dying from extrapulmonary progression. Acute toxicity was manageable, including one case of grade 3 RP (resolved with steroids). Mean heart dose was 7.39 ± 0.81 Gy and lung V20 was 19.15 ± 5.03%. All plans achieved satisfactory target coverage with D95% ≥ prescription dose for both PTVall and PTVp.

HT-based WLI with SIB provides excellent target coverage and satisfactory OAR sparing, is feasible and adaptable in complex settings, and achieves encouraging short-term local control in pulmonary metastatic Ewing's sarcoma; caution is warranted regarding radiation pneumonitis risk with concurrent immunotherapy.