Abstract
To assess the therapeutic response for metastatic breast cancer with (18)F-FDG position emission tomography (PET), this retrospective study aims to compare the performance of six different metabolic metrics with PERCIST, PERCIST with optimal thresholds, and an image-based parametric approach. Thirty-six metastatic breast cancer patients underwent 128 PET scans and 123 lesions were identified. In a per-lesion and per-patient analysis, the performance of six metrics: maximum standardized uptake value (SUVmax), SUVpeak, standardized added metabolic activity (SAM), SUVmean, metabolic volume (MV), total lesion glycolysis (TLG), and a parametric approach (SULTAN) were determined and compared to the gold standard (defined by clinical assessment and biological and conventional imaging according RECIST 1.1). The evaluation was performed using PERCIST thresholds (for per-patient analysis only) and optimal thresholds (determined by the Youden criterion from the receiver operating characteristic curves). In the per-lesion analysis, 210 pairs of lesion evolutions were studied. Using the optimal thresholds, SUVmax, SUVpeak, SUVmean, SAM, and TLG were significantly correlated with the gold standard. SUVmax, SUVpeak, and SUVmean reached the best sensitivity (91, 88, and 83%, respectively), specificity (93, 95, and 97%, respectively), and negative predictive value (NPV, 90, 88, and 83%, respectively). For the per--patient analysis, 79 pairs of PET were studied. The optimal thresholds compared to the PERCIST threshold did not improve performance for SUVmax, SUVpeak, and SUVmean. Only SUVmax, SUVpeak, SUVmean, and TLG were correlated with the gold standard. SULTAN also performed equally: 83% sensitivity, 88% specificity, and NPV 86%. This study showed that SUVmax and SUVpeak were the best parameters for PET evaluation of metastatic breast cancer lesions. Parametric imaging is helpful in evaluating serial studies.
Highlights
Metastatic breast cancer is initially diagnosed in 6–10% of cases and during follow-up in 30% of cases [1]
The optimal thresholds defined by the Youden criterion, were 21% for SUVmax, 23% for SUVpeak, 29% for SUVmean, 48% for standardized added metabolic activity (SAM), 33% for metabolic volume (MV), and 20% for total lesion glycolysis (TLG)
Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy values, and Youden correlation coefficients were calculated for their optimal threshold (Table 2)
Summary
Metastatic breast cancer is initially diagnosed in 6–10% of cases and during follow-up in 30% of cases [1]. The accurate and early assessment of therapeutic efficacy represents a major challenge but is crucial for limiting toxicity and reducing expensive treatments. RECIST has a number of intrinsic limitations such as moderate reproducibility of tumor measurement [3], late occurrence of morphological response compared to early metabolic changes, not applicable with non-measurable morphological lesions (bone lesions, lymphangitis, and effusions), and in targeted cytostatic therapies. Specific evaluation criteria for metabolic responses have been previously defined. These include measures of quantitative metrics and visual analysis tools to classify tumor progression and response, as defined by the European Organization for Research and Treatment of Cancer (EORTC) [6] or PERCIST [3]
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