Shanghai General Hospital, Shanghai Jiaotong University Shanghai, Shanghai
G. Yan1, C. Li2, G. Zhao1, Y. Liu1, Y. Feng3, M. Wu1, S. Yao1, X. Chen1, Q. Liu1, Z. Hu1, and Y. Hu1; 1Department of Radiation Oncology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China, 2University of Cambridge, Cambridge, United Kingdom, 3Department of Radiology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
Purpose/Objective(s):The heterogeneity of malignant tumors is closely related to biological behavior, treatment response and prognosis of the tumors. This study aims to develop a noninvasive quantitative method of intratumoral heterogeneity (ITH) based on pretreatment magnetic resonance images (MRI) scans for predicting treatment response and prognosis in patients with locally advanced nasopharyngeal carcinoma (LA-NPC), thereby developing quantitative heterogeneity for further individualized therapy. Materials/
Methods: 145 patients with stage III-IVA NPC enrolled in this retrospective study were treated by induction chemotherapy (IC) followed by concurrent chemoradiotherapy (CCRT) from January 2012 to August 2019. The clinical information and pretreatment MRI scans were collected. We employed Gaussian mixture model (GMM) for unsupervised clustering and identified tumor subregions, Habitat1 and Habitat2 (hereafter, H1 and H2) based on the MRI scans. Results: We found that the volumes of H1 and H2 were associated with local control and patient survival. The tumor objective response rate (ORR) in the group below cut-off value of H1/Pretreatment tumor volume% (H1/VPre%) was 100% (77/77), but 4.4% (3/68) of patients in the group above the cut-off value didn’t achieve treatment response (P = .101). In the group below cut-off value, the 5-year LRFS rate was 3.9% (3/77), but 19.1% (13/68) of patients in the group above the cut-off value experienced local recurrence within five years (P = .004, Pearson Chi = 8.523). Univariable analysis showed that the group below cut-off value of H1/VPre% had better local recurrence-free survival (LRFS, Hazard Risk [HR], 5.303 [95% CI: 1.507, 18.665]; P = .004), disease-free survival (DFS, HR, 2.451[95% CI: 1.289, 4.662]; P = .004) and overall survival (OS, HR, 3.302 [95% CI: 1.501, 7.726]; P = .002) than the group above the cut-off value. Multivariate analysis showed that H1/VPre% was the only independent prognostic indicator for LRFS (P = .009). Conclusion: The habitats identified by MRI can reflect ITH in LA-NPC, which are critical indicators for treatment response and prognosis.