ESTRO 2024 - Abstract Book

S1618

Clinical - Lung

ESTRO 2024

We extracted data from IRB-approved database to record compliance and toxicity associated with CPAP-assisted RT/SBRT in patients treated for lung, mediastinal, and breast cancers. Data recorded included RT indications, treatment techniques, total dose and fraction number, compliance with CPAP, and reasons for refusing or discontinuing treatment, including occurrence of treatment related adverse events (TRAE) unrelated to CPAP use. The CPAP protocol used a full-face mask to deliver pressurized room air, increased gradually from 5cm H2O to 15cm H2O over 15-30 minutes and sustained at the target pressure during planning scans and treatment delivery (example in figure 1). We grouped patients according to treatment indications and radiation techniques, and used regression analysis to compare subgroups, selecting patients receiving breast treatment as the reference subgroup.

Results:

Between 2014-2023, 315 patients received 396 courses of CPAP-RT/SBRT in 3,862 fractions. Characteristics included a mean age of 63 years (range 26-86 years), with 116 (37%) being male and 36 (11.4%) receiving concomitant chemotherapy (CTX). Table 1 summarizes treatment indications, techniques, and reasons for refusing or discontinuing CPAP assistance. Fourteen (4.4%) refused CPAP-RT/SBRT prior to treatment, either before treatment-planning (n=8, 2.5%) or after planning (n=6, 1.9%), due to discomfort or chest pain. Ten (3%) discontinued CPAP after starting treatment due to; presyncope/vertigo (n=3, 1%), syncope (n=1, 0.3%), hypertension (n=2, 0.6%), hoarseness (n=1, 0.3%), or discomfort (n=3, 1%). Subgroup analysis revealed that compared to breast treatments, most interruptions occurred when receiving fractionated CPAP-RT to the chest or mediastinum (n=7/84, 8%, OR 6.6, p=0.04), particularly with concomitant CTX (n=5/36, 14%, OR 12, p=0.006). Few treatment interruptions occurred during lung CPAP-SBRT (n=2/156, 0.9%, OR 0.96, p=0.97) or hypo-fractionated mediastinal CPAP-RT (n=2/34, 5.7%, OR 4.6, p=0.18).