The impact of age on the efficacy of radiotherapy in pleural mesothelioma patients receiving trimodality therapy: a population-based study of the SEER database

Background: Pleural mesothelioma (PM) is a highly aggressive tumor with poor survival outcomes. The role of additional radiotherapy for PM patients who have received surgery and chemotherapy remains controversial. In this study, we aim to evaluate the impact of age on the effectiveness of additional radiotherapy in order to identify the populations that may benefit from the trimodality therapy. Methods: We designed a case-control study and retrospectively selected PM patients who underwent surgery and chemotherapy, with or without radiotherapy, from the Surveillance, Epidemiology, and End Results (SEER) database (2000-2019). Kaplan-Meier curves were performed to compare the overall survival (OS) and cancer-specific survival (CSS) between the surgery + chemotherapy group and the trimodality therapy group. Propensity score matching (PSM) was used to balance the clinical characteristics and reduce potential confounding effects. Results: A total of 745 patients were selected, of which 515 received surgery + chemotherapy and 230 received trimodality therapy. For patients aged 50 to <65 years, additional radiotherapy showed better OS (3-year: 34.78% vs. 23.92%, P=0.02) and CSS (3-year: 36.15% vs. 25.46%, P=0.04) compared to surgery + chemotherapy. Similar results were observed after PSM (3-year OS: 38.76% vs. 26.53%, P=0.02; 3-year CSS: 40.49% vs. 26.92%, P=0.02). No significant benefit of radiotherapy was seen for patients aged <50 and >= 65 years, both before and after PSM. Conclusions: Our findings reveal that trimodality therapy is associated with better OS and CSS compared to surgery + chemotherapy for patients aged 50 to <65 years. These patients might obtain a benefit from additional radiotherapy.