ESTRO 2024 - Abstract Book

S1746

Clinical - Lung

ESTRO 2024

underwent non-radical surgery (64 pleurectomy +/- decortication and 53 biopsy only) and systemic platinum-based doublet chemotherapy (23 neoadjuvant and 94 adjuvant) prior to RHR. At T0 evaluation 50 patients were classified G0, 29 G1, 34 G2 and 4 G3. At T1 evaluation acute toxicities were almost all resolved. The persistence of 2 G1, 1 G2 and 1 G3 was recorded. At T2 evaluation only one G1 was observed. No correlation was found between oesophageal toxicity occurrence and demographic characteristics or previous treatments (chemotherapy or surgery). By considering univariate analysis (Fisher's exact test), a statistically significant relationship (p=0.002) was observed comparing patients with G0 vs. G2-G3 toxicity when the oesophageal circumference was entirely covered by the 47.5 Gy isodose. A statistically significant difference (Mann-Whitney test) was observed when comparing V30 (p<0.001), V50 (p<0.001) and D0.1 (p=0.005), Dmean (p<0.001) in both G0 vs. G2-G3 and G0 vs. G1 (Figure 1). However, by using a multivariate statistical approach (ANOVA test), only V30 (p=0.023) and V50 (p=0.009) were independent risk factors for oesophageal toxicity (G0 vs G1-G3).

Conclusion:

In our experience no RHR treatment was discontinued due to oesophageal toxicity and only 4 patients (3.4%) required hospitalization. Acute toxicity, such as the occurrence of dysphagia, was observed to resolve within 6 months in almost all cases. Patients’ age, disease’s laterality and previously performed treatments were not associated with the development of acute oesophageal toxicity. We observed that circumferential involvement of the oesophagus within the isodose of 47,5 Gy was significantly correlated (p<0.001) with the development of G2/G3 oesophagitis. Among the dosimetric parameters considered, V30 and V50 appear to be the best predictors of oesophageal toxicity even with a multivariate statistical approach.

Keywords: mesothelioma, esophagus, toxicity