Heterogeneity of targeted lung lesion predicts platinum-based first-line therapy outcomes and overall survival for metastatic triple-negative breast cancer patients with lung metastasis: a “PET biopsy” method
Authors Xie Y, Gu B, Hu X, Zhang Y, Zhang J, Wang Z, Zhao Y, Gong C, Li Y, Yang Z, Wang B
Received 6 February 2019
Accepted for publication 5 May 2019
Published 2 July 2019 Volume 2019:11 Pages 6019—6027
Checked for plagiarism Yes
Review by Single-blind
Peer reviewer comments 3
Editor who approved publication: Dr Chien-Feng Li
Yizhao Xie,1,2,* Bingxin Gu,2–5,* Xichun Hu,1,2 Yingjian Zhang,2–5 Jian Zhang,1,2 Zhonghua Wang,1,2 Yannan Zhao,1,2 Chengcheng Gong,1,2 Yi Li,1,2 Zhongyi Yang,2–5 Biyun Wang,1,2
1Department of Medical Oncology, Fudan University Shanghai Cancer Center, Shanghai, People’s Republic of China; 2Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, People’s Republic of China; 3Department of Nuclear Medicine, Fudan University Shanghai Cancer Center, Shanghai, People’s Republic of China; 4Center for Biomedical Imaging, Fudan University, Shanghai, People’s Republic of China; 5Shanghai Engineering Research Center of Molecular Imaging Probes, Shanghai, People’s Republic of China
*These authors contributed equally to this work
Background: Platinum-based chemotherapy is widely used as first-line therapy for metastatic triple-negative breast cancer (mTNBC). Intratumor heterogeneity derived from fluorine-18 fluorodeoxyglucose (18,F-FDG) positron emission tomography/computed tomography (PET/CT) is a potential predictor of treatment outcomes and the prognosis of breast cancer. However, the presence of multiple lesions and complex calculation methods leads to difficulties in the clinical use of this parameter for metastatic breast cancer. The aim of this study is to provide a convenient and effective measurement of intratumor heterogeneity to predict treatment outcomes for mTNBC patients with lung metastasis.
Patients and methods: We enrolled mTNBC patients with lung metastasis who underwent 18,F-FDG PET/CT scans before ﬁrst‐line therapy from three clinical trials (NCT01287624, NCT02341911 and NCT02546934). Apart from the regular FDG parameters, including standard uptake value (SUV), total lesion glycolysis (TLG) and metabolic tumor volume (MTV), we defined the lung index as the SUVmean divided by the difference between the SUVmax and SUVmean for the targeted lung lesion. The MTV was automatically exported from the manual delineation using software based on an adaptive threshold of SUV intensity >2.5 within the contouring margin. The TLG was calculated using the following formula: TLG=SUVmean×MTV. Progression‐free survival (PFS) and overall survival were estimated by the Kaplan–Meier method, and univariate and multivariate analyses were performed using the Cox proportional hazard model.
Results: The data from 31 patients were available for analysis. The median PFS of low-lung index (LI) patients was 8.1 months, which was significantly longer than that of high-LI patients (HR=3.3, 95% CI 1.5–7.3, p=0.003). Patients with low TLG had a significantly better PFS than those with high TLG (HR=2.6, 95% CI 1.2–5.8, p=0.014). Patients with low TLG had significantly longer overall survival than those with high TLG (31.2 months vs 13.9 months, HR=3.1, 95% CI 1.2–8.6, p=0.029). Multivariate analysis confirmed the predictive value of LI and TLG.
Conclusions: This study proposed a new “PET biopsy” method to evaluate the intratumor heterogeneity of mTNBC on pretreatment 18,F-FDG PET/CT scans and indicated the predictive value of LI and TLG for first-line platinum-based treatment outcomes and overall survival. These findings could help clinicians recognize patients who are likely to not only have a favorable response to platinum-based therapy but also a good prognosis.
Keywords: triple-negative breast cancer, chemotherapy, PET, tumor heterogeneity
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