ESTRO 2024 - Abstract Book

S1773

Clinical - Lung

ESTRO 2024

1 Hospital Universitario de Navarra, Radiation Oncology, Pamplona, Spain. 2 Hospital Universitario de Navarra, Radiophysics and radiological protection, Pamplona, Spain

Purpose/Objective:

Treatment of stage I lung cancer with SBRT has been common practice for many years. However, during this period there have been changes in the way treatments are carried out, including improvements in TC4D, IGRT and the way RT is planned and administered. Also in the role played by the different professionals involved in the treatment. In this work we want to analyze the results of our department, comparing the first period in which pulmonary SBRT was performed with recent years.

Material/Methods:

We analyze two different time periods.

Period 1 (2011-2016): For planning, a CT4D was used to generate the MOT and a margin of 5mm was applied to perform the PTV. Treatment was performed in a Varian Trilogy ™ accelerator, using coplanar and non-coplanar fields or conformal arcs. BodyFix ™ was used as an immobilization system. As IGRT, 2 CBCTs were performed before treatment. No respiratory control system was used during treatment. All treatment fractions were directed by a physician. The physicist was present in the first fraction. Period 2 (2020-2022): The ITV and PTV are generated the same as in period 1. The treatment is performed in a Varian TrueBeam ™ accelerator using conformal arcs or VMAT. The immobilization system has been simplified employing a Monarch ™ Overhead Arm Positioner system and BodyProlock ™ abdominal compression system. During the treatment, monitoring of the respiratory cycle is carried out, interrupting the treatment beam when breathing goes beyond the pre-established range. 2 CBCTs are performed before treatment and in the first fraction a post-treatment CBCT. If the displacements in this CBCT are not significant, it is not repeated in the other fractions. In the first fraction a physicist and a doctor are present. In the other fractions SBRT are directed by the RTTs.

We analyze our results retrospectively in terms of overall survival (OS), cause-specific survival (CSS), progression free survival (PFS) and local progression-free survival (LPFS).

For this study we considered the age, sex and ECOG of the patients, whether we had histological confirmation, the diagnosis date and date of last revision or death.

Statistical analyses were carried out using Kaplan-Meier and Log-Rank tests performed using SPSS.

Results:

132 patients were analyzed, 47 from period 1 and 85 from period 2.

Median age was 76y for period 1 and 75y for period 2.

Patients with an histological confirmation was 57% in period 1 and 48% in period 2.

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