PET Response Criteria In Solid Tumors Research Articles

Metabolic Imaging of Advanced Basal Cell Carcinoma Treated with Sonidegib: A Retrospective Case Series Study.

Background: Positron emission tomography/computed tomography (PET/CT) with 18F-fluorodeoxyglucose (18F-FDG) is a firmly established tool in oncology and is gaining importance in dermato-oncology. However, its use in advanced basal cell carcinoma (BCC) is limited, with only a few case reports and a single study focused on vismodegib. This study evaluates the role of 18F-FDG PET/CT in advanced BCC treated with sonidegib. Methods: We retrospectively assessed the clinical data of patients with advanced BCC who underwent 18F-FDG PET/CT between January 2022 and January 2024. Inclusion criteria included histologically confirmed BCC, FDG-avid lesions on baseline PET/CT, and a minimum follow-up of 6 months. Metabolic response was assessed using the PET Response Criteria in Solid Tumors (PERCIST). Results: Four patients with advanced BCC treated with sonidegib were included, presenting with a total of 10 hypermetabolic lesions at baseline PET/CT. The mean interval between baseline and follow-up scans was 8.7 ± 1.6 months. According to PERCIST, two patients achieved a complete metabolic response (CMR), while the other two had stable metabolic disease (SMD). Low baseline-standardized uptake values (i.e., SUVmax, SUVmean) and reduced total lesion glycolysis (TLG) were associated with CMR. No relapses were observed during follow-up. Conclusions: This study suggests that 18F-FDG PET/CT may help identify advanced BCC patients who are likely to benefit from sonidegib treatment. Further research is needed to fully explore the potential of PET/CT in this specific clinical context.

Predictive Value of PERCIST for Locally Advanced Non-Small Cell Lung Cancer Treated with Preoperative Induction Therapy - A Multicenter Study in Japan.

Induction therapy followed by surgery is recommended as an alternative treatment strategy for locally advanced non-small cell lung cancer (NSCLC). Patients who achieve pathologic response after induction therapy have better outcomes than non-responders; therefore, therapeutic response must be evaluated. Recently, new approaches for monitoring therapeutic responses, which are based on 18F-Fluorodeoxyglucose positron emission tomography (FDG-PET), have been developed. In this study, we evaluated the predictive value of Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST), which uses standardized uptake values corrected for lean body mass (SUL) and total lesion glycolysis (TLG). A total of 130 patients in the Setouchi Lung Cancer Group who underwent FDG-PET imaging before and after induction therapy prior to a planned surgical resection for NSCLC between 2007 and 2016 were studied retrospectively. The pathologic responses of the primary lung tumors and metastatic lymph nodes were compared with their responses based on evaluation using PERCIST. Postoperative pathologic studies revealed pathologic complete response (pCR) in 42 (32.3%) patients. PERCIST was significantly correlated with pathologic response (p < 0.001). The sensitivity, specificity, and accuracy of PERCIST for predicting pCR were 16.7% (7/42), 88.6% (78/88), and 65.4% (85/130), respectively. Patients with pCR had significantly higher reduction rates in SULpeak for both primary lung tumors and metastatic lymph nodes and TLG for primary tumors than non-responders. In a multivariate Cox regression analysis, tumor site in upper lobes, reduction rate of TLG in primary tumor, and pathologic N0 were independent predictors of favorable recurrence-free survival (RFS). Our study suggested that PERCIST, especially the rate of TLG reduction rate, are useful to predict the pathological response and prognosis after induction therapy. Although improvement is necessary, PERCIST can be a promising method of the post-induction status in lung cancer. Further research is needed to confirm our findings.

Stereotactic Body Radiotherapy and Liver Transplant for Liver Cancer

Whether stereotactic body radiotherapy (SBRT) as a bridge to liver transplant for hepatocellular carcinoma (HCC) is effective and safe is still unknown. To investigate the feasibility of SBRT before deceased donor liver transplant (DDLT) for previously untreated unresectable HCC. In this phase 2 nonrandomized controlled trial conducted between June 1, 2015, and October 18, 2019, 32 eligible patients within UCSF (University of California, San Francisco) criteria underwent dual-tracer (18F-fluorodeoxyglucose and 11C-acetate [ACC]) positron emission tomography with computed tomography (PET-CT) and magnetic resonance imaging (MRI) with gadoxetate followed by SBRT of 35 to 50 Gy in 5 fractions, and the same imaging afterward while awaiting DDLT. Statistical analysis was performed on an intention-to-treat basis between October 1 and 31, 2023. Patients received SBRT followed by DDLT when matched deceased donor grafts were available. Coprimary end points were progression-free survival (PFS) and objective response rates (ORRs) by the Response Evaluation Criteria in Solid Tumors, version 1.1 (RECIST 1.1), modified RECIST (mRECIST), and PET Response Criteria in Solid Tumors (PERCIST). Secondary end points were local control rate, overall survival (OS), and safety. A total of 32 patients (median age, 59 years [IQR, 54-63 years]; 22 men [68.8%]) with 56 lesions received SBRT. After a median follow-up of 74.6 months (IQR, 40.1-102.9 months), the median PFS was 17.6 months (95% CI, 6.6-28.6 months), and the median OS was 60.5 months (95% CI, 29.7-91.2 months). The 5-year PFS was 39.9% (95% CI, 19.9%-59.9%), and the 5-year OS was 51.3% (95% CI, 31.7%-70.9%). In terms of number of patients, ORRs were 62.5% ([n = 20] 95% CI, 54.2%-68.7%) by RECIST 1.1, 71.9% ([n = 23] 95% CI, 63.7%-79.0%) by mRECIST, and 78.1% ([n = 25] 95% CI, 73.2%-86.7%) by PERCIST. In terms of number of lesions, ORRs were 75.0% ([n = 42] 95% CI, 61.6%-80.8%) by RECIST 1.1, 83.9% ([n = 47] 95% CI, 74.7%-90.6%) by mRECIST, and 87.5% ([n = 49] 95% CI, 81.3%-98.6%) by PERCIST. Twenty patients with 36 lesions received DDLT, of whom 15 patients (75.0%) with 21 lesions (58.3%) exhibited pathologic complete response. Multivariable analyses revealed that pretreatment metabolic tumor volume (MTV) based on ACC (hazard ratio [HR], 1.06 [95% CI, 1.01-1.10]; P = .01) and complete metabolic response (CMR) by PERCIST (HR, 0.31 [95% CI, 0.10-0.96]; P = .04) were associated with PFS, while pretreatment MTV based on ACC (HR, 1.07 [95% CI, 1.03-1.16]; P = .01), total lesion activity based on ACC (HR, 1.01 [95% CI, 1.00-1.02]; P = .02), and CMR by PERCIST (HR, 0.21 [95% CI, 0.07-0.73]; P = .01) were associated with OS. Toxic effects associated with SBRT were reported for 9 patients (28.1%), with 1 grade 3 event. This phase 2 nonrandomized controlled trial demonstrated promising survival and safety outcomes of SBRT before DDLT for unresectable HCC. Future randomized clinical trials are warranted.

Total metabolic tumor volume on 18F-FDG PET/CT is a game-changer for patients with metastatic lung cancer treated with immunotherapy

PurposeBecause of atypical response imaging patterns in patients with metastatic non-small cell lung cancer (NSCLC) treated with immune checkpoint inhibitors (ICPIs), new biomarkers are needed for a better monitoring of...

Patterns of radiological response to tebentafusp in patients with metastatic uveal melanoma.

Metastatic uveal melanoma (mUM) is a rare type of melanoma with poor outcomes. The first systemic treatment to significantly prolong overall survival (OS) in patients with mUM was tebentafusp, a bispecific protein that can redirect T-cells to gp-100 positive cells. However, the objective response rate according to Response Evaluation Criteria in Solid Tumors (RECIST) may underestimate the clinical impact of tebentafusp. As metabolic response assessed by PET Response Criteria in Solid Tumors (PERCIST) has been reported to better correlate with clinical outcome, we here compared the patterns of radiological and morphological responses in HLA-A*02:01-positive patients with mUM treated with tebentafusp. In the 19 enrolled patients, RECIST showed an overall response rate (ORR) of 10%, median progression-free survival of 2.8 months (95% CI 2.5-8.4), and median OS (mOS) of 18.8 months. In 10 patients, where both RECIST and PERCIST evaluation was available, the ORR was 10% for both; however, the PFS was longer for PERCIST compared to RECIST, 3.1 and 2.4 months, respectively. A poor agreement between the criteria was observed at all assessments (Cohen's kappa ≤0), yet they differed significantly only at the first on-treatment imaging ( P = 0.037). Elevated baseline LDH and age were associated with an increased risk for RECIST progression, while lymphocyte decrease after the first infusions correlated to reduced risk of RECIST progression. Detectable ctDNA at baseline did not correlate with progression. Early response to tebentafusp may be incompletely captured by conventional imaging, leading to a need to consider both tumor morphology and metabolism.

Posttreatment Surveillance Imaging After Radiation for Head and Neck Cancer

The role of surveillance imaging after treatment for head and neck cancer is controversial and evidence to support decision-making is limited. To determine the use of surveillance imaging in asymptomatic patients with head and neck cancer in remission after completion of chemoradiation. This was a retrospective, comparative effectiveness research review of adult patients who had achieved a complete metabolic response to initial treatment for head and neck cancer as defined by having an unequivocally negative positron emission tomography (PET) scan using the PET response criteria in solid tumors (PERCIST) scale within the first 6 months of completing therapy. The medical records of 501 consecutive patients who completed definitive radiation therapy (with or without chemotherapy) for newly diagnosed squamous cell carcinoma of the head and neck between January 2014 and June 2022 were reviewed. Surveillance imaging was defined as the acquisition of a PET with computed tomography (CT), magnetic resonance imaging (MRI), or CT of the head and neck region in the absence of any clinically suspicious symptoms and/or examination findings. For remaining patients, subsequent surveillance after the achievement of a complete metabolic response to initial therapy was performed on an observational basis in the setting of routine follow-up using history-taking and physical examination, including endoscopy. This expectant approach led to imaging only in the presence of clinically suspicious symptoms and/or physical examination findings. Local-regional control, overall survival, and progression-free survival based on assignment to either the surveillance imaging or expectant management cohort. This study included 340 patients (mean [SD] age, 59 [10] years; 201 males [59%]; 88 Latino patients [26%]; 145 White patients [43%]) who achieved a complete metabolic response during this period. There was no difference in 3-year local-regional control, overall survival, progression-free survival, or freedom from distant metastasis between patients treated with surveillance imaging vs those treated expectantly. In this comparative effectiveness research, imaging-based surveillance failed to improve outcomes compared with expectant management for patients who were seemingly in remission after completion of primary radiation therapy for head and neck cancer.

Comparación del valor pronóstico de diferentes criterios de respuesta metabólica determinados por PET/TC en pacientes con cáncer de mama metastásico en tratamiento con inhibidores de CDK 4/6

PurposeThis study evaluates the prognostic role of different [18F]FDG PET/CT metabolic response criteria in metastatic breast cancer (MBC) patients treated with cyclin-dependent kinase 4/6 inhibitors (CDK 4/6). Materials and methodsWe retrospectively evaluated the data of MBC patients treated with CDK 4/6 inhibitors who underwent an [18F]FDG PET/CT scan before starting and during treatment. [18F]FDG PET/CT response was assessed with the European Organization for Research and Treatment of Cancer, PET response criteria in solid tumors (PERCIST), and whole-body total lesion glycolysis (WBTLG) criteria. Fleiss kappa was computed to assess the agreement between metabolic response criteria. The endpoint of the study was progression-free survival (PFS). PFS data were analyzed by the Kaplan–Meier method and compared using the log-rank test. ResultsThe study included 16 MBC patients who received CDK 4/6 inhibitors therapy. According to PERCIST, partial metabolic response (PMR) was found in seven patients, stable metabolic disease (SMD) in seven patients, and progressive metabolic disease (PMD) in two patients. According to the European Organization for Research and Treatment of Cancer, PMR was detected in eight patients, SMD in seven patients, and PMD in one patient. According to WBTLG, PMR was found in 10 patients, SMD in four patients, and PMD in two patients. There was a fair agreement between the three criteria. While progression was detected in seven of the patients during follow-up, no progression was detected in nine of them. Kaplan–Meier analysis revealed that the responders according to WBTLG showed significantly longer PFS than non-responders. ConclusionTreatment response according to WBTLG criteria during treatment appears to be associated with prolonged PFS in patients treated with CDK 4/6 inhibitors for MBC.

Comparison of prognostic value of different metabolic response criteria determined by PET/CT in patients with metastatic breast cancer under CDK 4/6 inhibitor treatment

PurposeThis study evaluates the prognostic role of different [18F]FDG PET/CT metabolic response criteria in metastatic breast cancer (MBC) patients treated with cyclin-dependent kinase 4/6 inhibitors (CDK 4/6). Materials and methodsWe retrospectively evaluated the data of MBC patients treated with CDK 4/6 inhibitors who underwent an [18F]FDG PET/CT scan before starting and during treatment. [18F]FDG PET/CT response was assessed with the European Organization for Research and Treatment of Cancer (EORTC), PET Response Criteria in Solid Tumors (PERCIST), and whole-body total lesion glycolysis (WBTLG) criteria. Fleiss kappa was computed to assess the agreement between metabolic response criteria. The endpoint of the study was progression-free survival (PFS). PFS data were analyzed by the Kaplan–Meier method and compared using the log-rank test. ResultsThe study included sixteen MBC patients who received CDK 4/6 inhibitors therapy. According to PERCIST, partial metabolic response (PMR) was found in seven patients, stable metabolic disease (SMD) in seven patients, and progressive metabolic disease (PMD) in two patients. According to EORTC, PMR was detected in eight patients, SMD in seven patients, and PMD in one patient. According to WBTLG, PMR was found in 10 patients, SMD in four patients, and PMD in two patients. There was a fair agreement between the three criteria. While progression was detected in seven of the patients during follow-up, no progression was detected in nine of them. Kaplan–Meier analysis revealed that the responders according to WBTLG showed significantly longer PFS than non-responders. ConclusionTreatment response according to WBTLG criteria during treatment appears to be associated with prolonged PFS in patients treated with CDK 4/6 inhibitors for MBC.

2-[18F]FDG-PET/CT is a better predictor of survival than conventional CT: a prospective study of response monitoring in metastatic breast cancer

This study aimed to compare CE-CT and 2-[18F]FDG-PET/CT for response monitoring metastatic breast cancer (MBC). The primary objective was to predict progression-free and disease-specific survival for responders vs. non-responders on CE-CT and 2-[18F]FDG-PET/CT. The secondary objective was to assess agreement between response categorization for the two modalities. Treatment response in women with MBC was monitored prospectively by simultaneous CE-CT and 2-[18F]FDG-PET/CT, allowing participants to serve as their own controls. The standardized response evaluation criteria in solid tumors (RECIST 1.1) and PET response criteria in solid tumors (PERCIST) were used for response categorization. For prediction of progression-free and disease-specific survival, treatment response was dichotomized into responders (partial and complete response) and non-responders (stable and progressive disease) at the first follow-up scan. Progression-free survival was defined as the time from baseline until disease progression or death from any cause. Disease-specific survival was defined as the time from baseline until breast cancer-specific death. Agreement between response categorization for both modalities was analyzed for all response categories and responders vs. non-responders. At the first follow-up, tumor response was reported more often by 2-[18F]FDG-PET/CT than CE-CT, with only fair agreement on response categorization between the two modalities (weighted Kappa 0.28). Two-year progression-free survival for responders vs. non-responders by CE-CT was 54.2% vs. 46.0%, compared with 59.1% vs. 14.3% by 2-[18F]FDG-PET/CT. Correspondingly, 2-year disease-specific survival were 83.3% vs. 77.8% for CE-CT and 84.6% vs. 61.9% for 2-[18F]FDG-PET/CT. Tumor response on 2-[18F]FDG-PET/CT was significantly associated with progression-free (HR: 3.49, P < 0.001) and disease-specific survival (HR 2.35, P = 0.008), while no association was found for tumor response on CE-CT. In conclusion, 2-[18F]FDG-PET/CT appears a better predictor of progression-free and disease-specific survival than CE-CT when used to monitor metastatic breast cancer. In addition, we found low concordance between response categorization between the two modalities.Trial registration: Clinical.Trials.gov. NCT03358589. Registered 30/11/2017-Retrospectively registered, http://www.ClinicalTrials.gov.

Comparative analysis of different response criteria at early phase after PD-1 blockade in non-small lung cancer

PurposeTo compare different response criteria using computed tomography (CT) and positron emission tomography (PET) in measuring response and survival in the early phase after programmed death-1 (PD-1) blockade monotherapy in patients with advanced non-small cell lung cancer (NSCLC).MethodsA total of 54 patients with advanced NSCLC who had 2-deoxy-2-[fluorine-18]-fluoro-D-glucose PET or CT at baseline, and 4 and 9 weeks after PD-1 blockade, were registered. Therapeutic response was assessed according to the Response Evaluation Criteria in Solid Tumors (RECIST), the immune-modified RECIST (irRECIST), the PET Response Criteria in Solid Tumors (PERCIST), the immune-modified PERCIST (iPERCIST), and the European Organization for Research and Treatment of Cancer (EORTC) criteria for dichotomous groups, such as responders vs. non-responders and controlled vs. uncontrolled diseases. Cohen’s κ was used to evaluate the concordance among the different criteria.ResultsThe concordance between CT and PET response criteria was fair or slight for responders vs. non-responders, but the agreement between iPERCIST and irRECIST was moderate for controlled vs. uncontrolled diseases. The agreement between EORTC and PERCIST or iPERCIST in detecting responders was higher in the application of metabolic tumor volume (MTV) and total lesion glycolysis (TLG) than in the standardized uptake value corrected for lean body mass (SUL)peak. To distinguish controlled from uncontrolled disease, RECIST, irRECIST, and PET criteria (PERCIST, iPERCIST, and EORTC) defined by MTV or TLG were found to be significant predictors of progression-free survival. To distinguish responders from non-responders, iPERCIST by SULpeak or EORTC by TLG were identified as significant indicators. The EORTC criteria using TLG for the detection of responders or uncontrolled diseases had a significantly higher predictive value for response assessment.ConclusionsThe EORTC criteria based on TLG for the early detection of responders and uncontrolled disease were effective as a response assessment at 4 weeks after the PD-1 blockade. When SULpeak was not used but MTV or TLG was, the agreement between EORTC and PERCIST or iPERCIST was almost perfect.

Radiographic Response of Solitary Plasmacytomas After Conformal Radiotherapy May Be Delayed: Outcomes in the 3D Era.

Although recurrence rates after radiotherapy for solitary plasmacytoma (SP) are well established, little is known about how SP responds radiographically, as most historical patients were treated in the 2D era. We evaluated the response to radiotherapy among SP patients staged and treated with 3D techniques, including proton therapy, which has not yet been previously reported. Between 2007 and 2021, 15 SP patients (4 extramedullary, 11 bone) staged with 3D imaging and bone marrow evaluation were consecutively treated with definitive radiotherapy. The best response was categorized in 9 evaluable patients according to response evaluation criteria in solid tumors (RECIST) and positron emission tomography response criteria in solid tumors (PERCIST). With a median follow-up of 34 months, 4 patients relapsed. The median time to the best response was ~2 years (26.6mo RECIST, 25.4mo PERCIST). Response rates differed based on response assessment criteria. PERCIST was associated with higher rates of complete (85.7%) or partial response (14.3%) compared with RECIST (16.7% complete, 33.3% partial). Two-year and 4-year PFS for extramedullary SP were 100% and 75%, compared with 91% and 55% for bone ( P =0.75). Patients treated with proton therapy (n=5) did not appear to have different patterns of relapse (1 marginal, 1 distant) compared with those treated with photons or electrons (n=10; 2 distant). More conformal dose distribution with proton therapy does not appear to alter patterns of recurrence. Although response rates differ based on criteria by both RECIST and PERCIST assessments, the radiographic response may be slow and requires validation in other cohorts.

SDHx mutations and temozolomide in malignant pheochromocytoma and paraganglioma

Malignant pheochromocytomas (PHEOs)/paragangliomas (PGLs) are rare tumors for which clinical outcomes remain poorly defined and therapeutic options are limited. Approximately 27% carry pathogenic germline succinate dehydrogenase (SDHx) mutations; the presence of such mutations has been correlated with response to temozolomide (TMZ). We aimed to investigate the association between germline mutations in SDHx and response to TMZ. We retrospectively identified patients with metastatic malignant PHEO/PGLs treated with TMZ- based chemotherapy at Dana-Farber Cancer Institute between 2003 and 2020. The correlation between response by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 and PET Response Criteria in Solid Tumors (PERCIST) and the presence of SDHx mutations in the germline and tumor was evaluated. Nineteen patients received TMZ. Seventeen underwent germline assessment: 9 (53%) carried a pathogenic SDHx germline mutation. Fifteen patients were evaluable for response by RECIST 1.1: 6 (40%) partial response, 4 (27%) stable disease, and 5 (33%) progressive disease. Overall median progression-free survival was 2.2 years. Three-year overall survival (OS) was 58%. Median PFS was 1.3 years and 5.5 years for carriers and non-carriers, respectively and OS was 1.5 years and not estimable for carriers and non-carriers, respectively. The response by PERCIST criteria in nine patients correlated with the RECIST 1.1 assessment. Our series represents one of the largest analyses of patients with malignant PHEOs/PGLs treated with TMZ who have available germline data. The incidence of pathogenic germline SDHx mutations was similar to what has been previously published, though our analysis suggests that there may be a limited association between response to TMZ and pathogenic germline SDHx mutations.

Artificial intelligence guided enhancement of digital PET: scans as fast as CT?

PurposeBoth digital positron emission tomography (PET) detector technologies and artificial intelligence based image post-reconstruction methods allow to reduce the PET acquisition time while maintaining diagnostic quality. The aim of this study was to acquire ultra-low-count fluorodeoxyglucose (FDG) ExtremePET images on a digital PET/computed tomography (CT) scanner at an acquisition time comparable to a CT scan and to generate synthetic full-dose PET images using an artificial neural network.MethodsThis is a prospective, single-arm, single-center phase I/II imaging study. A total of 587 patients were included. For each patient, a standard and an ultra-low-count FDG PET/CT scan (whole-body acquisition time about 30 s) were acquired. A modified pix2pixHD deep-learning network was trained employing 387 data sets as training and 200 as test cohort. Three models (PET-only and PET/CT with or without group convolution) were compared. Detectability and quantification were evaluated.ResultsThe PET/CT input model with group convolution performed best regarding lesion signal recovery and was selected for detailed evaluation. Synthetic PET images were of high visual image quality; mean absolute lesion SUVmax (maximum standardized uptake value) difference was 1.5. Patient-based sensitivity and specificity for lesion detection were 79% and 100%, respectively. Not-detected lesions were of lower tracer uptake and lesion volume. In a matched-pair comparison, patient-based (lesion-based) detection rate was 89% (78%) for PERCIST (PET response criteria in solid tumors)-measurable and 36% (22%) for non PERCIST-measurable lesions.ConclusionLesion detectability and lesion quantification were promising in the context of extremely fast acquisition times. Possible application scenarios might include re-staging of late-stage cancer patients, in whom assessment of total tumor burden can be of higher relevance than detailed evaluation of small and low-uptake lesions.

Rapid Standardized CT-Based Method to Determine Lean Body Mass SUV for PET-A Significant Improvement Over Prediction Equations.

In 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) studies, maximum standardized uptake value (SUVmax) is the parameter commonly used to provide a measurement of the metabolic activity of a tumor. SUV normalized by body mass is affected by the proportions of body fat and lean tissue, which present high variability in patients with cancer. SUV corrected by lean body mass (LBM), denoted as SUL, is recommended to provide more accurate, consistent, and reproducible SUV results; however, LBM is frequently estimated rather than measured. Given the increasing importance of a quantitative PET parameter, especially when comparing PET studies over time to evaluate disease response clinically, and its use in oncological clinical trials, we set out to evaluate the commonly used equations originally derived by James (1976) and Janmahasatian et al. (2005) against computerized tomography (CT)-derived measures of LBM.MethodsWhole-body 18F-FDG PET images of 195 adult patients with cancer were analyzed retrospectively. Representative liver SUVmean was normalized by total body mass. SUL was calculated using a quantitative determination of LBM based on the CT component of the PET/CT study (LBMCT) and compared against the equation-estimated SUL. Bland and Altman plots were generated for SUV-SUL differences.ResultsThis consecutive sample of patients undergoing usual care (men, n = 96; women, n = 99) varied in body mass (38–127 kg) and in Body Mass Index (BMI) (14.7–47.2 kg/m2). LBMCT weakly correlated with body mass (men, r2 = 0.32; women, r2 = 0.22), and thus SUV and SULCT were also weakly correlated (men, r2 = 0.24; women, r2 = 0.11). Equations proved inadequate for the assessment of LBM. LBM estimated by James’ equation showed a mean bias (overestimation of LBM compared with LBMCT) in men (+6.13 kg; 95% CI 4.61–7.65) and in women (+6.32 kg; 95% CI 5.26–7.39). Janmahasatian’s equation provided similarly poor performance.ConclusionsCT-based LBM determinations incorporate the patient’s current body composition at the time of a PET/CT study, and the information garnered can provide care teams with information with which to more accurately determine FDG uptake values, allowing comparability over multiple scans and treatment courses and will provide a robust basis for the use of PET Response Criteria in Solid Tumors (PERCIST) in clinical trials.

Comparison of Magnetic Resonance Imaging With Positron Emission Tomography/Computed Tomography in the Evaluation of Response to Neoadjuvant Therapy of Breast Cancer

IntroductionThe present study aims to determine the diagnostic accuracy of magnetic resonance imaging (MRI) and positron emission tomography–computed tomography (PET-CT) in predicting a pathological response of molecular subtypes of breast cancer to neoadjuvant chemotherapy (NAC). Materials and methodsWe retrospectively analyzed patients with breast cancer who were operated after NAC between January 2018 and May 2020. Radiological responses were evaluated as per the Response Evaluation Criteria in Solid Tumors (RECIST) and changes in contrast enhancement patterns on MRI and the classification of PET Response Criteria in Solid Tumors (PERCIST) on PET-CT. The presence of a pathological response was evaluated based on the Sataloff classification. The agreement between the radiological response determined through imaging modalities before and after the NAC and the postoperative pathological complete response (pCR) was evaluated and compared statistically. Among the patients diagnosed with breast cancer between the ages of 18 and 80 y, those with N (+) at the time of diagnosis, those with T2 and advanced tumors, and those who were planned for breast conserving surgery were included in our study. Male patients, patients with distant metastases at the time of diagnosis, and patients with other system malignancies were excluded. ResultsThe study included 88 patients who had undergone surgery for breast cancer after NAC between January 2018 and May 2020. The study was conducted retrospectively in a single center. The tumor diameters and standard uptake values significantly decreased after NAC (P < 0.001). Estrogen receptor (ER) and progesterone receptor (PR) positivity were negatively associated with pCR (P = 0.03 and P = 0.03, respectively), whereas there was a significant positive association between HER-2 positivity and pCR (P = 0.004). There was a moderate agreement between the RECIST criteria used with MRI and pCR (k: 0.46). Moreover, a good agreement between PET-CT-PERCIST and pCR was detected (k: 0.61). In predicting pCR after NAC, MRI showed a selectivity of 80.7%, a sensitivity of 65.2%, a positive predictive value (PPV) of 75%, and a negative predictive value (NPV) of 72.4%. The corresponding rates for PET-CT were 75.7%, 100%, 57.9%, and 100%. ConclusionsWhen evaluating pCR after NAC, MRI was found to be more sensitive in patients with ER-positive cancer cell nuclei with weak to medium staining intensity and a loss of E-cadherin expression, whereas PET-CT was found to be more sensitive in patients with HER-2 overexpression, Luminal B, or Ki-67 proliferation >14% (P = 0.01).

Assessment of Treatment Response to Lenvatinib in Thyroid Cancer Monitored by F-18 FDG PET/CT Using PERCIST 1.0, Modified PERCIST and EORTC Criteria-Which One Is Most Suitable?

Simple SummaryIn patients with progressive metastatic radioiodine-refractory differentiated thyroid cancer, tyrosine kinase inhibitor (TKI) therapy with lenvatinib improves progression-free survival. Early identification of patients with therapeutic responses to the TKI therapy is clinically relevant due to common side effects and toxicity. The use of metabolic response criteria derived from F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) imaging can help to identify those patients who benefit from treatment. In our study, we evaluated different response criteria, namely, the Positron Emission Tomography Response Criteria In Solid Tumors (PERCIST) and European Organization for Research and Treatment of Cancer (EORTC) criteria, to find out which system might be more reliable and suitable in everyday clinical practice. The EORTC criteria could be applied to all patients, and the different PERCIST criteria, in 80% and 88%, respectively. Regarding their survival and treatment responses, patients with a progressive disease could be reliably identified by using all the criteria.Background: We aimed to compare the established metabolic response criteria PERCIST and EORTC for their applicability and predictive value in terms of clinical response assessment early after the initiation of lenvatinib therapy in patients with metastatic radioiodine-refractory (RAI) thyroid cancer (TC). Methods: In 25 patients treated with lenvatinib, baseline and 4-month follow-up F-18 FDG PET/CT images were analyzed using PERCIST 1.0, modified PERCIST (using SUVpeak or SUVmax) and EORTC criteria. Two groups were defined: disease control (DC) and progressive disease (PD), which were correlated with PFS and OS. Results: PERCIST, mPERCIST, PERCISTmax and EORTC could be applied in 80%, 80%, 88% and 100% of the patients based on the requirements of lesion assessment criteria, respectively. With PERCIST, mPERCIST, PERCISTmax and EORTC, the patients classified as DC and PD ranged from 65 to 68% and from 32 to 35%, respectively. Patients with DC exhibited a longer median PFS than patients with PD for EORTC (p < 0.014) and for PERCIST and mPERCIST (p = 0.037), respectively. Conclusion: EORTC and the different PERCIST criteria performed equally regarding the identification of patients with PD requiring treatment changes. However, the applicability of PERCIST 1.0 using SULpeak seems restricted due to the significant proportion of small tumor lesions.

An evaluation of the response to neoadjuvant chemotherapy for osteosarcoma of extremities: PERCIST versus RECIST 1.1 criteria after long-term follow-up.

The aim of this study was to compare the recent Positron emission tomography (PET) Response Criteria in Solid Tumors (PERCIST) and Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 criteria for evaluating the response of osteosarcoma to neoadjuvant chemotherapy of the extremities. We retrospectively reviewed patients with osteosarcoma of the extremities who received neoadjuvant chemotherapy and then surgical resection at Peking University People's Hospital. Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) and magnetic resonance imaging (MRI) were performed prior to chemotherapy and before surgical resection. Therapeutic response was assessed separately by the PERCIST and RECIST 1.1 criteria. The association between the data acquired by the PERCIST and RECIST 1.1 criteria was then analyzed by Wilcoxon's signed-rank test. The association between the PERCIST criteria and the pathological necrosis rate was analyzed by Fisher's exact test. Finally, the impact of a range of clinicopathological factors on overall survival (OS) and event-free survival (EFS) was analyzed by Cox proportional hazards regression. We recruited 68 patients with a median follow-up of 74months (range 45-102months). The evaluations resulting from the RECIST 1.1 and PERCIST criteria were significantly different (p = 0.000). Only two responders were identified according to the RECIST 1.1 criteria. However, 34 responders were identified by the PERCIST criteria. Data arising from the PERCIST criteria were in accordance with the pathological necrosis rate. Survival analysis showed that metastasis at diagnosis, poor pathological response, and disease progression (according to the RECIST 1.1 or PERCIST criteria) were all associated with a poor prognosis (p < 0.05). Our data indicate that the PERCIST criteria are significantly more sensitive than RECIST 1.1 criteria to identify more responders when evaluating the response of osteosarcoma to neoadjuvant chemotherapy.

Evaluation of response to stereotactic body radiation therapy for nonsmall cell lung cancer: PET response criteria in solid tumors versus response evaluation criteria in solid tumors.

Recommendations for surveillance after stereotactic body radiation therapy (SBRT) for early-stage nonsmall cell lung cancer (NSCLC) are not well defined. Recently, PET response criteria in solid tumors (PERCIST) have been proposed as a new standardized method to assess radiotherapeutic response both quantitatively and metabolically. The aim of this study was to evaluate therapeutic response following SBRT in early-stage NSCLC patients by comparing PERCIST with the currently widely used RECIST. Forty-nine patients with early-stage NSCLC who had been prescribed SBRT were studied. Responses of lesion were evaluated using CT and 18F-FDG PET according to the RECIST and PERCIST methods. PET-CT scans were obtained before SBRT and 3-6 months after SBRT. Associations between overall survival (OS) and clinicopathologic results (histology, tumor location, tumor size, lymphatic invasion, clinical stage, and radiotherapeutic responses in RECIST and PERCIST) were statistically analyzed. The median patient follow-up was 30 months. Thirteen patients had stage IA, 9 stage IB, 10 stage IIA, and 17 stage IIB biopsy-proven NSCLC. Three-year OS was 79.6%. CT scans indicated three regional recurrences. PET-CT/chest indicated three regional recurrences and distant metastasis. Significant differences were observed in response classification between RECIST and PERCIST (Wilcoxon signed-rank test, P = 0.0041). Univariate analysis showed that clinical stage, RECIST, and PERCIST were significant factors associated with OS, whereas by multivariate analysis PERCIST was the only predictor of OS. SMD, PMD/PMR, and CMR in PERCIST criteria were indicative of a 9.900-fold increase in the risk of OS in early NSCLC patients [risk ratio, 9.900 (95% CI, 1.040-21.591); P = 0.001]. RECIST based on the anatomic size reduction rate did not demonstrate the correlation between radiotherapeutic response and prognosis in patients with early-stage NSCLC receiving SBRT. However, PERCIST was shown as the strongest independent predictor of outcomes. PERCIST might be considered more suitable for the evaluation of NSCLC tumor response to SBRT than RECIST.

18F-Fluorodeoxyglucose PET/CT for Early Prediction of Outcomes in Patients with Advanced Lung Adenocarcinomas and EGFR Mutations Treated with First-Line EGFR-TKIs.

Simple SummaryEpithelial growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) are the first-line therapy for patients with advanced-stage lung adenocarcinoma with EGFR mutations. However, 17–31% of these patients do not respond to therapy, making early evaluation of treatment response crucial. This prospective study investigates the value of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) for timely prediction of response and survival of these patients. We evaluated 30 patients with stage IIIB/IV lung adenocarcinomas and EGFR mutations, receiving first-line EGFR-TKI therapy. 18F-FDG PET/CT was performed before and two weeks after initiation of treatment. Positron Emission Tomography Response Criteria in Solid Tumors served as an independent predictor of non-progressive disease; baseline and change of metabolic tumor volume represented independent predictors of progression-free survival and overall survival, respectively. Therefore, 18F-FDG PET/CT is an early predictor of outcomes and individual prognosis of patients with stage IIIB/IV lung adenocarcinomas and EGFR mutations receiving first-line EGFR-TKI therapy.This study aims to investigate the role of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in early prediction of response and survival following epithelial growth factor receptor (EGFR)–tyrosine kinase inhibitor (TKI) therapy in patients with advanced lung adenocarcinomas and EGFR mutations. Thirty patients with stage IIIB/IV lung adenocarcinomas and EGFR mutations receiving first-line EGFR-TKIs were prospectively evaluated between November 2012 and May 2015. EGFR mutations were quantified by delta cycle threshold (dCt). 18F-FDG PET/CT was performed before and 2 weeks after treatment initiation. PET response was assessed based on PET Response Criteria in Solid Tumors (PERCIST). Baseline and percentage changes in the summed standardized uptake value, metabolic tumor volume (bsumMTV and ΔsumMTV, respectively), and total lesion glycolysis of ≤5 target lesions/patient were calculated. The association between parameters (clinical and PET) and non-progression disease after 3 months of treatment in CT based on the Response Evaluation Criteria in Solid Tumors Version 1.1 (nPD3mo), progression-free survival (PFS), and overall survival (OS) were tested. The median follow-up time was 19.6 months. The median PFS and OS were 12.0 and 25.3 months, respectively. The PERCIST criteria was an independent predictor of nPD3mo (p = 0.009), dCt (p = 0.014) and bsumMTV (p = 0.014) were independent predictors of PFS, and dCt (p = 0.014) and ΔsumMTV (p = 0.005) were independent predictors of OS. 18F-FDG PET/CT achieved early prediction of outcomes in patients with advanced lung adenocarcinomas and EGFR mutations receiving EGFR-TKIs.

Imaging response assessment for oncology: An algorithmic approach

Treatment response assessment by imaging plays a vital role in evaluating changes in solid tumors during oncology therapeutic clinical trials. Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 is the reference standard imaging response criteria and provides details regarding image acquisition, image interpretation and categorical response classification. While RECIST 1.1 is applied for the majority of clinical trials in solid tumors, other criteria and modifications have been introduced when RECIST 1.1 outcomes may be incomplete. Available criteria beyond RECIST 1.1 can be explored in an algorithmic fashion dependent on imaging modality, tumor type and method of treatment. Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST) is available for use with PET/CT. Modifications to RECIST 1.1 can be tumor specific, including mRECIST for hepatocellular carcinoma and mesothelioma. Choi criteria for gastrointestinal stromal tumors incorporate tumor density with alterations to categorical response thresholds. Prostate Cancer Working Group 3 (PCWG3) imaging criteria combine RECIST 1.1 findings with those of bone scans. In addition, multiple response criteria have been created to address atypical imaging responses in immunotherapy.