ESTRO 2024 - Abstract Book

S2251

Clinical - Upper GI

ESTRO 2024

Respiratory Motion Management using CPAP in Radiotherapy for Liver Tumors : a prospective trial

Won Young Suh 1 , Se Ho Kwon 2 , Seongmoon Jung 1 , Bo-Gyum Kim 1 , Joo Ho Lee 1,3 , Ji Hyun Jang 1,3 , Hak Jae Kim 1,3 , Eui Kyu Chie 1,3 , Jaeman Son 1 , Hyun-Woo Shin 4,5 , Kyung Su Kim 1,3 1 Seoul National University Hospital, Radiation Oncology, Seoul, Korea, Republic of. 2 Seoul National University Hospital, Office of Education & Research, Seoul, Korea, Republic of. 3 Seoul National University College of Medicine, Department of Radiation Oncology, Seoul, Korea, Republic of. 4 Seoul National University College of Medicine, Obstructive Upper airway Research (OUaR) Laboratory, Seoul, Korea, Republic of. 5 Seoul National University Hospital, Department of Otorhinolaryngology-Head and Neck Surgery, Seoul, Korea, Republic of

Purpose/Objective:

The objective of the study is to analyze the effect of Continuous Positive Airway Pressure (CPAP) on tumor excursion, liver volume and dose in patients receiving Radiation Therapy (RT) for liver tumors.

Material/Methods:

Patients with primary or secondary liver tumors were enrolled on a prospective Institutional Review Board (IRB) approved phase II clinical trial, utilizing CPAP during RT. Each patient was simulated and planned with CPAP and without CPAP (CPAP/noCPAP). Conventional abdomen compression (AC) method was used to control respiratory motion of noCPAP patients. Patients were instructed to breath with the CPAP device via a full-face mask and the pressure was increased to a maximum of 20cm H2O. We compared tumor excursion, volume, and dosimetric parameters of both treatment plans. We recorded both CPAP-related and radiation-related adverse events at the simulation, after every treatment, and at two-month follow-up.

Results:

Out of eighty-six patients who were enrolled, 17 dropped out, including 13 who withdrew due to discomfort. In total, treatment plans of sixty-two patients with 69 lesions were available for full volumetric and dosimetric comparison. With CPAP, Superior-Inferior (SI) tumor excursion was reduced by 0.26 cm (95% Confidence Interval [CI] 0.15 – 0.36, p<0.0001). We could not find significant reduction of tumor motion in Right-Left (RL) or Anterior-Posterior (AP) direction. In addition, implementation of CPAP did not have a significant impact on liver volume (p=0.10). On average, CPAP reduced Planning Target Volume (PTV) by 14.9% (95% CI 5.0% - 24.8%, p=0.004), which resulted in a mean decrease in MLD by 1.2 Gy (95% CI 0.6 – 1.8, p=0.003). The reduction in MLD was independent of age, sex, and tumor location. Furthermore, CPAP decreased Liver V5Gy, V10Gy, V20Gy, V30Gy, and V40Gy by 10.2% (95% CI 5.2% - 15.2%, p=0.0001), 12.9% (95% CI 6.6% - 19.3%, p=0.001), 17.9% (95% CI 6.3% - 29.5%), p=0.003), 21.6% (95% CI, 6.0%-37.4%, p=0.008), and 25.9% (95% CI 6.9% - 44.9%, p=0.008), respectively.

Conclusion: