ESTRO 2023 - Abstract Book

S1132

Digital Posters

ESTRO 2023

Conclusion In our analysis older patients who underwent CRT showed the same rates of grade ≥ 3 acute and late toxicities compared to younger patients. OS and DFS resulted significant lower in patients with age ≥ 70 years. Baseline haemoglobin level <10 gm/dl resulted predictive of worse OS and DFS, suggesting that a supplement supportive therapy in elderly patients may be necessary.

PO-1402 SBRT for pulmonary metastasis of colorectal cancer: biologically effective dose 150 Gy is preferred

T.H. Lee 1 , H. Kang 1 , E.K. Chie 1 , H.J. Kim 1 , H. Wu 1 , J.H. Lee 1 , K.S. Kim 1

1 Seoul National University Hospital, Department of Radiation Oncology, Seoul, Korea Republic of

Purpose or Objective This study aimed to compare the local control (LC) rate of pulmonary metastatic lesions in colorectal adenocarcinoma treated with stereotactic body radiation therapy (SBRT) using a biologically effective dose with an α / β ratio of 10 (BED10) of 150 Gy. Materials and Methods We analyzed 231 pulmonary metastatic lesions from colorectal adenocarcinoma treated with SBRT in 135 patients. The patients were referred for the control of oligometastatic or oligoprogressive disease in the lungs. A dose of 40–60 Gy in 3– 8 fractions was delivered to the lung nodules by SBRT. The LC per tumor treated with BED10 was evaluated. The LC rate per patient, pulmonary progression-free survival (PPFS), any progression-free survival (APFS), and overall survival (OS) were reported as clinical outcomes. Results A significant difference was observed in the LC per tumor between the BED10 < 100 Gy group, 100 ≤ BED10 < 150 Gy group, and BED10 ≥ 150 Gy group (p < 0.001). The 1-, 2, and 3-year LC rates per tumor were 38.9%, 25.9%, and 25.9% in the BED10 < 100 group, 84.1%, 62.6%, and 60.4% in the 100 ≤ BED10 < 150 Gy group, and 97.3%, 94.9%, and 85.2% in the BED10 ≥ 150 Gy group, respectively. Actuarial rates of LC per tumor by BED groups are illustrated in the following figure. BED10 ≥ 150 Gy (hazard ratio 0.247, 95% confidence interval 0.125–0.488, p < 0.001) remained significant in the multivariate analysis of LC rate per tumor. The 3-year LC per patient, PPFS, APFS, and OS rates were 62.7%, 26.5%, 24.8%, and 67.7%, respectively. Oligoprogression (vs. oligometastasis), multiple pulmonary nodules, and extrapulmonary metastasis were associated with a poor prognosis.