2496 - Comparison of Efficacy between Osteolytic vs. Osteoblastic Metastatic Lesion in Lung Cancer Following Radiotherapy

D. J. Chen¹, J. Liang², W. Jiang³, J. Lu⁴, K. Xu⁵, M. Zhao⁴, and S. Han⁶; ¹National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital,Chinese Academy of Medical Sciences and Peking Union Medical College,Shenzhen,518116,China, ShenZhen, China, ²National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital,Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, Shenzhen, China, ³Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, China, ⁴National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital,Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, ShenZhen, China, ⁵Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, China, Shenzhen, China, ⁶National Cancer Center / National Cancer Clinical Research Center / Cancer Hospital / Shenzhen Hospital, Chinese Academy of Medical Sciences, Shenzhen 518116, China., Shzhen, China

Purpose/Objective(s): Lung cancer can develop both osteolytic and osteoblastic metastases to bone. However, the difference in the efficacy of radiotherapy in these two types of lesions is unknown. This study aimed to compare the difference between osteolytic vs osteoblastic metastatic lesions on radiotherapy efficacy in lung cancer. Materials/

Methods: A retrospective analysis was conducted for lung cancer patients who received bone radiotherapy from November 2019 to November 2023. The patients were divided into two groups: the osteoblastic group and the osteolytic group. The pain response was obtained 2 weeks after radiotherapy. Similarly, the radiologic response was accessed 3 months after radiotherapy according to the MD-Anderson criteria (Response categories are divided into complete response (CR), partial response (PR), stable disease (SD), progressive disease (PD), PR and CR are considered to be radiologic response). Pain response was defined as a decrease in worst pain NRS score of at least 2 points. And the overall survival (OS) and bone progression-free survival (bPFS) rates were analyzed between the two groups.
Results: A total of 94 lung cancer patients including 59 patients with osteolytic metastases and 35 patients with osteoblastic metastases were retrospectively recruited. 84.9% of the patients were diagnosed with adenocarcinoma. The prescribed dose was 20Gy to 60Gy in 4 to 13 fractions. Biological effective dose (BED) ranged from 28Gy to 96Gy. No difference was found between the two groups for BED (p=0.692). Compared with the osteolytic group, a significantly higher objective pain response rate was observed in the osteoblastic group (64.9% vs 81.3%, P<0.001). Further analysis indicated that there was not any difference between the two groups for the radiologic response (p=0.128). Moreover, the osteolytic group was observed longer bPFS than the osteoblastic group (p=0.048). Conversely, there was a trend for longer OS in the osteoblastic group, but the result was not statistically significant ( median OS: 46.88 months for the osteolytic group vs 52.4 months for the osteoblastic group, p=0.130).
Conclusion: Pain control of osteoblastic lesions was better than that of osteolytic lesions after radiotherapy for lung cancer. Moreover, patients with osteoblastic lesions may probably have longer OS, but bPFS is inferior to that of patients with osteolytic lesions. More studies are needed to determine the radiosensitivity between osteoblastic lesions and osteolytic lesions.