The tolerance of proton radiotherapy — preliminary results

Streszczenie

Introduction. Because the specific proton beam dose distribution (i.e. the so-called ’Bragg curve’), proton radiotherapy ensures that the high-dose region is precisely confined to the target volume while minimizing the dose delivered to healthy tissues/critical organs surrounding the tumour or to those lying in the path of the proton beam. This method has been used for patients in Kraków since November 2016.

Aim. To report the early tolerance outcomes to proton radiotherapy in patients completing their treatment just before the end of August 2017.

Materials and methods. Study subjects were 47 patients who had completed their treatment before the end of August 2017 with a mean age of 41.6 years (range: 16–76, median: 40). The most frequent diagnoses were skull base tumours (22 pts. — 46.8%) and brain G1 or G2 gliomas (17 pts. — 36.2%), whereas the most frequent histological types were chordomas (17 pts. — 36.2%). Proton radiotherapy was administered by pencil beam scanning and consisted of using the intensity modulated proton therapy (IMPT) technique. The total dose given per cancer type averaged as follows: (i) 70 and 74 Gy(RBE), for respectively chodrosarcomas and chordomas, (ii) 54 Gy(RBE) for brain gliomas and (iii) 70 Gy(RBE) for paranasal sinuses tumours. Early tolerance was prospectively evaluated and measured according to the CTCAE scale, version 4.03.

Results. In all, 91 side effects (SE) were recorded in 44 patients. The intensity of SEs were as following: 62 SEs (68.1%) were of grade 1 intensity, 21 SEs (23.1%) were of grade 2 and 8 SEs (8.8%) were of grade 3. The most frequently developed SEs were skin reactions (29 pts. — 61.7%) or oral/pharyngeal mucositis (20 pts. — 42.6%). Because the patient follow-up period was short, presented results only describes the early tolerance to this therapy. Our findings of mild intensities for the most early side effects, at (grades 1 or 2) are consistent with other published studies.