Fagundes Theara C, Mafra Arnoldo, Silva Rodrigo G, Castro Ana C G, Silva Luciana C, Aguiar Priscilla T, Silva Josiane A, P Junior Eduardo, Machado Alexei M, Mamede Marcelo
Oncology Section, University Hospital, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
Radiation Therapy Section, Instituto Mario Penna, Belo Horizonte, MG, Brazil.
Rev Assoc Med Bras (1992). 2018 Feb;64(2):119-126. doi: 10.1590/1806-9282.64.02.119.
The standard treatment for locally advanced rectal cancer (RC) consists of neoadjuvant chemoradiation followed by radical surgery. Regardless the extensive use of SUVmax in 18F-FDG PET tumor uptake as representation of tumor glycolytic consumption, there is a trend to apply metabolic volume instead. Thus, the aim of the present study was to evaluate a noninvasive method for tumor segmentation using the 18F-FDG PET imaging in order to predict response to neoadjuvant chemoradiation therapy in patients with rectal cancer.
The sample consisted of stage II and III rectal cancer patients undergoing 18F-FDG PET/CT examination before and eight weeks after neoadjuvant therapy. An individualized tumor segmentation methodology was applied to generate tumor volumes (SUV2SD) and compare with standard SUVmax and fixed threshold (SUV40%, SUV50% and SUV60%) pre- and post-therapy. Therapeutic response was assessed in the resected specimens using Dworak's protocol recommendations. Several variables were generated and compared with the histopathological results.
Seventeen (17) patients were included and analyzed. Significant differences were observed between responders (Dworak 3 and 4) and non-responders for SUVmax-2 (p<0.01), SUV2SD-2 (p<0.05), SUV40%-2 (p<0.05), SUV50%-2 (p<0.05) and SUV60%-2 (p<0.05). ROC analyses showed significant areas under the curve (p<0.01) for the proposed methodology with sensitivity and specificity varying from 60% to 83% and 73% to 82%, respectively.
The present study confirmed the predictive power of the variables using a noninvasive individualized methodology for tumor segmentation based on 18F-FDG PET/CT imaging for response evaluation in patients with rectal cancer after neoadjuvant chemoradiation therapy.
局部晚期直肠癌（RC）的标准治疗包括新辅助放化疗，随后进行根治性手术。尽管SUVmax在18F-FDG PET肿瘤摄取中被广泛用于代表肿瘤糖酵解消耗，但现在有使用代谢体积的趋势。因此，本研究的目的是评估一种使用18F-FDG PET成像进行肿瘤分割的非侵入性方法，以预测直肠癌患者对新辅助放化疗的反应。
样本包括在新辅助治疗前和治疗八周后接受18F-FDG PET/CT检查的II期和III期直肠癌患者。应用一种个体化的肿瘤分割方法来生成肿瘤体积（SUV2SD），并与标准SUVmax以及治疗前后的固定阈值（SUV40%、SUV50%和SUV60%）进行比较。使用德沃拉克方案建议对切除标本的治疗反应进行评估。生成了几个变量，并与组织病理学结果进行比较。
纳入并分析了17名患者。在反应者（德沃拉克3级和4级）和无反应者之间，观察到SUVmax-2（p<0.01）、SUV2SD-2（p<0.05）、SUV40%-2（p<0.05）、SUV50%-2（p<0.05）和SUV60%-2（p<0.05）存在显著差异。ROC分析显示，所提出方法的曲线下面积显著（p<0.01），敏感性和特异性分别在60%至83%和73%至82%之间变化。
本研究证实了使用基于18F-FDG PET/CT成像的非侵入性个体化肿瘤分割方法所生成变量对直肠癌患者新辅助放化疗后反应评估的预测能力。
