ESTRO 2024 - Abstract Book

S2147

Clinical - Upper GI

ESTRO 2024

1 University Medical Centre Groningen, Department of Radiation Oncology, Groningen, Netherlands. 2 University Medical Centre Groningen, Department of Surgery, Groningen, Netherlands. 3 Martini Hospital Groningen, Department of Surgery, Groningen, Netherlands. 4 University Medical Centre Groningen, Department of Medical Oncology, Groningen, Netherlands. 5 University Medical Center Utrecht, Department of Medical Humanities, Utrecht, Netherlands

Purpose/Objective:

Current multimodal treatment in oesophageal cancer consists of neoadjuvant chemoradiotherapy (nCRT) followed by surgical resection. This treatment is associated with serious complication risks, of which pneumonia is one of the most frequently observed complications. The incidence of pulmonary complications depends on the mean dose to the lungs 1 . Photon-based radiotherapy (PhRT) has been the standard treatment approach for a long time. However, proton radiotherapy (PRT) has emerged as a promising alternative since reductions in radiation dose to healthy tissues can be obtained 2,3 . An recent randomized controlled trial showed that the dose reduction achieved by PRT significantly reduced the risk of developing adverse events, including pneumonia and re-intubation 4 .

The main aim of the current analysis was to test the hypothesis that PRT can effectively reduce the occurrence of pneumonia among patients undergoing multimodal treatment for oesophageal cancer.

Material/Methods:

At our centre, all curatively treated oesophageal cancer patients are enrolled in a prospective data registry. For the current analysis, patients who underwent nCRT between October 2014 and June 2022 followed by a surgical resection within 6 months after the end of nCRT were included. Excluded were those with a history of thoracic radiotherapy/resection and those diagnosed with neuroendocrine carcinoma. Since April 2020, oesophageal cancer patients can be selected for PRT using the model-based approach. In this study, a complete case association analysis was performed to analyse the impact of patient, treatment and tumour characteristics on the risk of pneumonia. Differences in baseline characteristics between the PRT and PhRT groups were identified with a Chi-Square-test or the Mann-Witney-U-test. Pneumonia was defined as CTCAE grade 2 or higher within 6 months after the end of nCRT. A univariable logistic regression analysis was performed to identify parameters that associate with pneumonia (p<0.2). To evaluate potential confounding, possible confounders were introduced into the univariable model of the variable it possible influenced (10% coefficient chance). Subsequently, variables that were significant in the univariable analysis were multiplied within a logistic regression model to assess potential interactions (p<0.1). All significant variables were subsequently incorporated into a multivariable logistic regression analysis (p<0.05) using backward selection. Volumes at radiation doses in intervals of 5Gy (V5,..., V40) of the heart and lungs were calculated to analyse the effect of the DVH parameters. To cope with the multicollinearity of the DVH parameters, a principal component analysis (PCA) analysis was performed.

Results:

The study was composed of 316 patients who met the eligibility criteria, of which 9 patients were excluded because of missing variables. This left 307 complete cases for the analysis. Baseline characteristics were comparable between the PRT and the PhRT groups except for the surgical variables (time between end nCRT and surgery, surgical approach and anastomosis). The incidence of pneumonia was 32% after PhRT compared to 12% after PRT