Dose-averaged linear energy transfer within the gross tumor volume of non-small-cell lung cancer affects the local control in carbon-ion radiotherapy

• Published in: Radiotherapy and oncology Vol. 201; p. 110584
• Main Authors: Li, Guangsheng, Ma, Ningyi, Wang, Weiwei, Chen, Jian, Mao, Jingfang, Jiang, Guoliang, Wu, Kailiang
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier B.V 01.12.2024
• Subjects: Carbon-ion radiotherapy; Linear energy transfer; Local control; Locally-advanced non-small-cell lung cancer; Carbon-ion radiotherapy; Local control; Linear energy transfer; Locally-advanced non-small-cell lung cancer
• ISSN: 0167-8140; 1879-0887; 1879-0887
• DOI: 10.1016/j.radonc.2024.110584

•Linear energy transfer affect local control of lung cancer with carbon-ion radiotherapy.•LETd in iGTV in the local recurrence group was lower than the local control group.•LETd distribution within iGTV should be routinely assessed in CIRT for lung cancer. High linear energy transfer (LET) radiation exhibits stronger tumor-killing effect. However, the correlation between LET and the therapeutic efficacy in Carbon-ion radiotherapy (CIRT) for locally advanced non-small-cell lung cancer (LA-NSCLC) is currently not clear. This study aimed to investigate the relationship between the dose-averaged LET (LETd) distribution within tumor and local recurrence for LA-NSCLC treated with CIRT. An analysis of 62 consecutive patients with LA-NSCLC who underwent CIRT from 2018 to 2022 was conducted. The LETd distribution was calculated based on their treated plans, and the correlation between local recurrence and LETd, relative biological effectiveness (RBE)-weighted doses (DRBE) and clinical factors was investigated. Receiver operating characteristic (ROC) curve, log-rank test, and Cox regression analysis were performed based on that. 16 patients were defined as local recurrence. Overall survival (OS) and local control (LC) at 24 months were 76.9 % and 73.2 %, respectively. The mean LETd in internal gross tumor volume (iGTV) in the local recurrence group was 48.7 keV/µm, significantly lower than the mean LETd of 53.2 keV/µm in the local control group (p = 0.016). No significant difference was observed in DRBE between the local recurrence and local control groups. ROC curve analysis indicated that a percentage of 88 % of volume in iGTV receiving at least 40 keV/µm (V40keV/μm) is the optimal threshold for predicting local recurrence (Area under curve (AUC) = 0.7636). The log-rank test and Cox regression analysis revealed that the LETd value covering 98 % volume of iGTV (LETd98%) was a significant risk factor for LC (p = 0.020). Our study revealed an association between LETd distribution and local recurrence in patients with LA-NSCLC. These findings suggest that lower LETd may increase the probability of local recurrence. We suggest that LETd distribution within iGTV should be routinely assessed in CIRT for lung cancer.