ESTRO 2025 - Abstract Book

S1591

Clinical – Mixed sites & palliation

ESTRO 2025

Toxicity has been defined at the end of the treatment using Common Terminology Criteria Adverse Event (CTCAE V4.0) scale. Data have been prospectively collected in a proton registry (“Power Registry” NCT0586036).

Results: Among 129 pts treated in the considered period with PT, 67 pts (52%) (mean age 65 yrs, 30 female) have been treated with PT reRT. All but 2 pts had a diagnosis of malignant disease. Distribution of tumor site were reported in Fig.1. The majority (42.63%) of pts were treated in the curative setting, while 20 (30%) pts and 3 (4%) pts were treated in the postoperative and palliative setting, respectively. A standard fractionation (< 2Gy/fraction RBE) and a slight hypofractionation (from 2.1 to 3 Gy/fraction RBE) schedules were used for 15 (22%) pts and 21 (31%) pts, respectively. Dose/fraction according tumor site were reported in Fig.2. At the end of treatment toxicity data were available for 55 (82%) pts. Grade 2 toxicity were recorded in 10 (15%) pts, the majority of them treated for head and neck (3 pts) and breast (3 pts) cancers. Four pts experienced a G3 toxicity: 2 breast, 1 central nervous system (snc) cancers and 1 head and neck. During the follow up period 1 patient had a G4 toxicity (acute hemorrage) and 1 pts had a G3 skin toxicity (chest wall irradiation). Clinical follow up (mean 5 months, range 1-9 months) was available for 37 (55%) pts. Among 19 pts treated with curative intent, 13 (68%), 4 (21%) and 2 (11%) achieved a complete response, partial response and stable disease, respectively. In the post-operative setting (14 pts) all pts were free from disease while one patient died for systemic recurrences. Three patients progressed and died before the first follow up (2 curative and one post-operative patient).