Predictive value of pretreatment metabolic activity measured by fluorodeoxyglucose positron emission tomography in patients with metastatic advanced gastric cancer: the maximal SUV of the stomach is a prognostic factor

Prognostic value of the metabolic score obtained via [18F]FDG PET/CT and a new prognostic staging system for gastric cancer

We developed and validated a new staging system that includes metabolic information from pretreatment [¹⁸F]Fluorodeoxyglucose ([¹⁸F]FDG) positron emission tomography/computed tomography (PET/CT) for predicting disease-specific survival (DSS) in gastric cancer (GC) patients. Overall, 731 GC patients undergoing preoperative [¹⁸F]FDG PET/CT were enrolled and divided into the training (n = 543) and validation (n = 188) cohorts. A metabolic score (MS) was developed by combining the maximum standardized uptake value (SUVmax) of the primary tumor (T_SUVmax) and metastatic lymph node (N_SUVmax). A new staging system incorporating the MS and tumor-node-metastasis (TNM) stage was developed using conditional inference tree analysis. The MS was stratified as follows: score 1 (T_SUVmax ≤ 4.5 and N_SUVmax ≤ 1.9), score 2 (T_SUVmax > 4.5 and N_SUVmax ≤ 1.9), score 3 (T_SUVmax ≤ 4.5 and N_SUVmax > 1.9), and score 4 (T_SUVmax > 4.5 and N_SUVmax > 1.9) in the training cohort. The new staging system yielded five risk categories: category I (TNM I, II and MS 1), category II (TNM I, II and MS 2), category III (TNM I, II and MS ≥ 3), category IV (TNM III, IV and MS ≤ 3), and category V (TNM III, IV and MS 4) in the training cohort. DSS differed significantly between both staging systems; the new staging system showed better prognostic performance in both training and validation cohorts. The MS was an independent prognostic factor for DSS, and discriminatory power of the new staging system for DSS was better than that of the conventional TNM staging system alone.

Prognostic Value of Restaging F-18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography to Predict 3-Year Post-Recurrence Survival in Patients with Recurrent Gastric Cancer after Curative Resection

OBJECTIVE

The aim of this study was to investigate the prognostic value of the maximum standardized uptake value (SUV_max) measured while restaging with F-18 fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) to predict the 3-year post-recurrence survival (PRS) in patients with recurrent gastric cancer after curative surgical resection.

MATERIALS AND METHODS

In total, 47 patients with recurrent gastric cancer after curative resection who underwent restaging with ¹⁸F-FDG PET/CT were included. For the semiquantitative analysis, SUV_max was measured over the visually discernable ¹⁸F-FDG-avid recurrent lesions. Cox proportional-hazards regression models were used to predict the 3-year PRS. Differences in 3-year PRS were assessed with the Kaplan-Meier analysis.

RESULTS

Thirty-nine of the 47 patients (83%) expired within 3 years after recurrence in the median follow-up period of 30.3 months. In the multivariate analysis, SUV_max (p = 0.012), weight loss (p = 0.025), and neutrophil count (p = 0.006) were significant prognostic factors for 3-year PRS. The Kaplan-Meier curves demonstrated significantly poor 3-year PRS in patients with SUV_max > 5.1 than in those with SUV_max ≤ 5.1 (3-year PRS rate, 3.5% vs. 38.9%, p < 0.001).

CONCLUSION

High SUV_max on restaging with ¹⁸F-FDG PET/CT is a poor prognostic factor for 3-year PRS. It may strengthen the role of ¹⁸F-FDG PET/CT in further stratifying the prognosis of recurrent gastric cancer.

Low metabolic activity in primary gastric adenocarcinoma is associated with resistance to chemoradiation and the presence of signet ring cells

PURPOSES

Preoperative chemoradiation is a potential treatment option for localized gastric adenocarcinoma (GAC). Currently, the response to chemoradiation cannot be predicted. We analyzed the pretreatment maximum standardized uptake value (SUVmax) and total lesion glycolysis (TLG) on positron emission tomography/computed tomography as potential predictors of the response to chemoradiation.

METHODS

We analyzed the SUVmax and TLG data from 59 GAC patients who received preoperative chemoradiation. We used logistic regression models to predict a pathologic complete response (pCR) and Kaplan-Meier curves to determine overall survival among patients with high and low SUVmax or TLG.

RESULTS

Twenty-nine patients (49%) had Siewert type III adenocarcinoma and 30 (51%) had tumors located in the lower stomach. Forty-one patients had poorly differentiated GAC, and 26 had signet ring cells. The median SUVmax was 7.3 (0-28.2) and the median TLG was 56.6 (0-1881.5). Patients with signet ring cells had a low pCR rate, as well as a low SUVmax and TLG. In the multivariable logistic regression model, high SUVmax was a predictor of pCR (odds ratio = 11.1, 95% confidence interval = 2.12-50.0, p = 0.004). Overall survival was not associated with the SUVmax (log-rank p = 0.69) or TLG (log-rank p = 0.85) CONCLUSION: A high SUVmax was associated with sensitivity to chemoradiation and pCR in GAC, and signet ring cells seemed to confer resistance.

Prognostic Value of Metabolic Information in Advanced Gastric Cancer Using Preoperative 18F-FDG PET/CT

Purpose

This study evaluated the usefulness of semiquantitative and volumetric PET parameters for predicting prognosis in patients with advanced gastric cancer (AGC).

Methods

We enrolled 213 patients who underwent ¹⁸F-fluoro-2-deoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) prior to curative surgery for AGC. Maximum standardized uptake value (SUVmax) and tumor-to-liver uptake ratio (TLR) were measured in all patients. Metabolic tumor volume (MTV) and total lesion glycolysis were measured in volume-measurable patients. For further quantification of FDG uptake, we developed PET prognostic scores by combining SUVmax and MTV (1: low SUVmax/low MTV; 2: high SUVmax/low MTV; 3: high SUVmax/high MTV). Comparison of PET parameters between recurrence and non-recurrence groups was performed. Univariate and multivariate analyses for recurrence-free survival (RFS) and overall survival (OS) were subsequently performed.

Results

The recurrence rate was 32.4% (69/213 patients). Mean SUVmax and mean MTV of the recurrence group were significantly higher than those of the non-recurrence group (p = 0.026 and p = 0.025). TLR showed marginal significance (p = 0.051). In multivariate analysis for RFS including all patients, SUVmax (p = 0.022), TLR (p = 0.010), and PET score (p = 0.003) were independent prognostic factors. In post hoc analysis of PET score, significant differences in RFS were observed between PET scores 2 and 3 as well as scores 1 and 3. No significant difference in RFS was observed between scores 1 and 2. Only PET score was statistically significant for OS in univariate analysis. None of the PET parameters were statistically significant for OS in multivariate analysis.

Conclusion

High SUVmax and high MTV of the primary tumor suggest a high risk of recurrence for AGC patients. Even if SUVmax is similar, the prognosis may vary depending on MTV. Combining PET parameters results in a better prediction for prognosis.

A 18FDG PET/CT-based volume parameter is a predictor of overall survival in patients with local advanced gastric cancer

Objective

The present study investigated the prognosis value of preoperative fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in patients with local advanced gastric cancer (LAGC).

Methods

In total, 144 patients [median age 63 (range: 48−80) years old] with LAGC underwent¹⁸F-FDG PET/CT prior to any treatment. The maximum standardized uptake values (SUV_max), mean standardized uptake values (SUV_mean), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) of the primary lesion were measured on PET/CT and correlated with clinicopathological features and survival.

Results

Significant differences in SUV_mean, SUV_max, MTV and TLG were found according to Lauren’s classification, histologic grade and T category (P<0.05). During the 26.5-month follow-up, 51 (35.4%) patients died and 70 (48.6%) exhibited disease progression. The optimal thresholds of MTV and TLG were 15.1 cm³ and 47.3 cm³, respectively. The 3-year progression-free survival (PFS) and overall survival (OS) for patients with high TLG values were 30% and 38% compared to 38% and 47% for low TLG values, respectively (P<0.05). Univariate and multifactor analyses demonstrated that lymph node metastasis and T stage were independent prognostic factors for PFS; T stage, histologic grade and TLG were independent prognostic factors for OS (P<0.05). Molecular markers had no relationship with patient’s outcomes.

Conclusions

Metabolic activity of primary gastric tumors from ¹⁸F-FDG PET/CT is a prognostic factor in patients with LAGC.

Gastric cancer and image-derived quantitative parameters: Part 2-a critical review of DCE-MRI and 18F-FDG PET/CT findings

Abstract

There is yet no consensus on the application of functional imaging and qualitative image interpretation in the management of gastric cancer. In this second part, we will discuss the role of image-derived quantitative parameters from dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) in gastric cancer, as both techniques have been shown to be promising and useful tools in the clinical decision making of this disease. We will focus on different aspects including aggressiveness assessment, staging and Lauren type discrimination, prognosis prediction and response evaluation. Although both the number of articles and the patients enrolled in the studies were rather small, there is evidence that quantitative parameters from DCE-MRI such as K^trans, V_e, K_ep and AUC could be promising image-derived surrogate parameters for the management of gastric cancer. Data from ¹⁸F-FDG PET/CT studies showed that standardised uptake value (SUV) is significantly associated with the aggressiveness, treatment response and prognosis of this disease. Along with the results from diffusion-weighted MRI and contrast-enhanced multidetector computed tomography presented in Part 1 of this critical review, there are additional image-derived quantitative parameters from DCE-MRI and ¹⁸F-FDG PET/CT that hold promise as effective tools in the diagnostic pathway of gastric cancer.

Key Points

• Quantitative analysis from DCE-MRI and¹⁸F-FDG PET/CT allows the extrapolation of multiple image-derived parameters.

• Data from DCE-MRI (K^trans, V_e, K_ep and AUC) and ¹⁸F-FDG PET/CT (SUV) are non-invasive, quantitative image-derived parameters that hold promise in the evaluation of the aggressiveness, treatment response and prognosis of gastric cancer.

PET/CT in thyroid nodule and differentiated thyroid cancer patients. The evidence-based state of the art

A more conservative approach to the clinical management of thyroid nodules and differentiated thyroid cancer has recently been proposed by the 2015 ATA guidelines. In this context, fine-needle aspiration biopsy has been reserved for nodules with particular ultrasound features or dimensions that exclude low-risk thyroid lesions. Accordingly, a less aggressive surgical approach (i.e. lobectomy) has been recommended as the first-choice treatment in nodules with indeterminate cytology or in small cytologically confirmed malignant nodules. At the same time, radioactive remnant ablation has been considered only for DTC patients with concrete risks of disease persistence/relapse after thyroidectomy. In addition, further radioactive iodine therapies (RAI) have been proposed only for patients presenting unresectable and iodine-avid structural relapse. In this complex scenario, which requires attention to each clinical aspect of the patient, the introduction of accurate diagnostic tools is highly warranted. PET/CT is a very sensitive and specific diagnostic procedure that can better characterize the risk of thyroid nodules, identify DTC relapse early and predict the response to RAI. Thus, it seems essential to customize a more conservative approach to thyroid nodules and DTC patients. The aim of this review is to report the principal clinical context in which PET/CT has been used and to evaluate the evidence-based support for each diagnostic indication.

Prognostic value of metabolic parameters on preoperative 18F-fluorodeoxyglucose positron emission tomography/ computed tomography in patients with stage III gastric cancer

This study investigated the prognostic value of metabolic parameters determined by 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in patients with stage III gastric cancer. Patients with pre-operative PET/CT and confirmed stage III after curative surgical resection were retrospectively enrolled. Parameters evaluated from pre-operative PET/CTwere maximum standardized uptake value (SUV_max) and peak SUV (SUV_peak) of primary tumor, SUV_max or SUV_peak of tumor to liver ratio (TLR_max and TLR_peak). Volumetric parameters, metabolic tumor volume (MTV) and total lesion glycolysis (TLG), were also evaluated. These PET/CT parameters were compared with the overall survival (OS) and recurrence-free survival (RFS). From total of 133 consecutive patients, tumor recurrence was found in 54 patients (40.6%) and 53 died during the follow-up period (median, 43 mo; range 5-62). In univariate analysis, SUV_max, SUV_peak, TLR_max and TLR_peak were significantly associated with the OS and RFS. In multivariate analysis, high TLR_max and TLR_peak were significantly unfavorable prognostic factors for RFS (both P<0.05) even after adjusting for age, depth of tumor invasion, lymph node metastasis, and chemotherapy. MTV and TLG showed no statistically significant correlation with outcome. In conclusion, glucose metabolism of primary tumor measured by pre-operative PET/CT provides prognostic information, especially for recurrence, in stage III gastric cancer.

Value of Preoperative PET-CT in the Prediction of Pathological Stage of Gastric Cancer

BACKGROUND

Preoperative precise staging is essential for the treatment of gastric cancer (GC); however, the diagnostic accuracy of conventional modalities needs to be increased. The present study investigated the clinical value of positron emission tomography-computed tomography (PET-CT) for the staging of GC.

METHODS

This was a retrospective study of 117 patients with a clinical diagnosis of advanced GC who underwent PET-CT followed by gastrectomy. The incidence of FDG uptake in the primary tumor or lymph nodes and its relationship with clinicopathological factors, particularly pathological stage (pStage) III/IV, were examined.

RESULTS

FDG uptake in the primary tumor was noted in 83 patients (70.9%). FDG uptake in the lymph nodes was detected in 21 patients (17.9%), and its sensitivity and specificity for lymph node metastasis were 22.7 and 90.5%, respectively. Multiple logistic regression analyses showed that FDG uptake in the primary tumor (odds ratio (OR) 2.764; 95% confidence interval (CI) 1.104-7.459, p = 0.029) and that in the lymph nodes (OR 4.660; 95% CI 1.675-13.84, p = 0.003) were factors independently associated with pStage III/IV. FDG uptake in the primary tumor detected pStage III/IV with higher sensitivity (80.4%) and that in lymph nodes found pStage III/IV with higher specificity (88.7%) than those of upper endoscopy plus CT (60.9 and 67.6%, respectively).

CONCLUSIONS

PET-CT appears to be a useful complementary modality in the assessment of pStage III/IV because of the high sensitivity of FDG uptake in the primary tumor and the high specificity of FDG uptake in the lymph nodes.

The prognostic value of volume-based parameters using 18F-FDG PET/CT in gastric cancer according to HER2 status

BACKGROUND

We aimed to find the clinical value of metastatic tumor burden evaluated with F18-FDG PET/CT in gastric cancer patients, considering the human epidermal growth factor receptor 2 (HER2) status.

METHODS

We retrospectively reviewed 124 patients with locally advanced or metastatic gastric cancer at Yonsei Cancer Center between January 2006 and December 2014 who had undergone baseline FDG PET/CT before first-line chemotherapy. We measured the maximum standardized uptake value from the primary tumor (SUV_max) and whole-body (WB) PET/CT parameters, including WB SUV_max, WB SUV_mean, WB metabolic tumor volume (WB MTV), and WB total lesion glycolysis (WB TLG), in all metabolically active metastatic lesions (SUV threshold ≥2.5 or 40% isocontour for ≤2.5), and we determined their association with patient survival outcomes.

RESULTS

SUV_max was higher in HER2-positive gastric cancers (median 12.1, range 3.4-34.6) compared to HER-2 negative (7.4, 1.6-39.1, P < 0.001). Among all patients, WB TLG > 600, which is indicative of a high metastatic tumor burden, showed worse progression-free survival (PFS) [hazard ratio (HR), 2.003; 95% CI, 1.300-3.086; P = 0.002] and overall survival (OS) (HR, 3.001; 95% CI, 1.950-4.618; P < 0.001) than did WB TLG ≤ 600. Among HER2-positive gastric cancer patients treated with trastuzumab, higher metabolic tumor burden predicted worse OS, but not PFS.

CONCLUSIONS

HER2-positive gastric cancers had higher SUV_max compared to HER2-negative gastric cancers. In both HER2-negative patients and -positive patients receiving trastuzumab, FDG PET/CT volume-based parameters may have a role in further stratifying the prognosis of stage IV gastric cancer.

18F-FDG PET/CT is a prognostic biomarker in patients affected by bone metastases from breast cancer in comparison with 18F-NaF PET/CT

Aim: To compare 18F-FDG PET/CT and 18F-NaF PET/CT with respect to disease prognostication and outcome in patients affected by bone metastases from breast cancer (BC). Patients, methods: We retrospectively investigated 32 women with BC and documented bone metastases. Semi-quantitative parameters were applied to 18F-FDG PET/CT and 18F-Na PET/CT in order to evaluate disease extent and tumour metabolism. We used time-to-event analyses (Kaplan Meier and COX proportional hazard methods) to estimate progression-free (PFS) and overall survival (OS) in order to assess the independent prognostic value of 18F-FDG PET/CT and 18F-Na PET/CT. Results: The sensitivity of 18F-NaF PET/CT (100%) was higher (p < 0.05) than that of 18F-FDG PET/CT (72% and 72%). None of the 18F-FDG PET/CT-negative patients showed disease progression at the end of follow-up. After adjustment for age, Ki-67 levels, presence of visceral metastases, hormone therapy, duration of bone disease and response to first-line therapy, only 18F-FDG SUV mean [HR 15.7, 95% confidence interval (CI) 1.15-214.5] and 18F-FDG whole-body bone metabolic burden (WB-B-MB) (HR 16.9; 95%CI 1.87-152.2) were independently and significantly associated with OS. None of the 18F-NaF PET/CT parameters were associated with OS. None of the conventional clinical prognostic parameters remained significantly associated with OS after the inclusion of PET/ CT parameters in the model. Conclusion: 18F-FDG PET/CT is independently associated with OS in BC patients with bone metastases and its prognostic impact seems to be higher than conventional clinical and biological prognostic factors. Although 18F-NaF PET/CT has a higher diagnostic sensitivity than 18F-FDG PET/ CT, it is not independently associated with OS.

Potential Utility of FDG PET-CT as a Non-invasive Tool for Monitoring Local Immune Responses

Purpose

The tumor microenvironment is known to be associated with the metabolic activity of cancer cells and local immune reactions. We hypothesized that glucose metabolism measured by 2-deoxy-2-(¹⁸F)fluoro-D-glucose (¹⁸F-FDG) positron emission tomography (PET)-computed tomography (CT) (¹⁸F-FDG PET-CT) would be associated with local immune responses evaluated according to the presence of tumor infiltrating lymphocytes (TILs).

Materials and Methods

We retrospectively reviewed 56 patients who underwent ¹⁸F-FDG PET-CT prior to gastrectomy. In resected tumor specimens, TIL subsets, including cluster of differentiation (CD) 3, CD4, CD8, Forkhead box P3 (Foxp3), and granzyme B, were subjected to immunohistochemical analysis. The prognostic nutritional index (PNI) was calculated as: (10×serum albumin value)+(0.005×peripheral lymphocyte counts). Additionally, the maximum standard uptake value (SUV_max) was calculated to evaluate the metabolic activity of cancer cells.

Results

The SUV_max was positively correlated with larger tumor size (R=0.293; P=0.029) and negatively correlated with PNI (R=−0.407; P=0.002). A higher SUV_max showed a marginal association with higher CD3 (+) T lymphocyte counts (R=0.227; P=0.092) and a significant association with higher Foxp3 (+) T lymphocyte counts (R=0.431; P=0.009). No other clinicopathological characteristics were associated with SUV_max or TILs. Survival analysis, however, indicated that neither SUV_max nor Foxp3 held prognostic significance.

Conclusions

FDG uptake on PET-CT could be associated with TILs, especially regulatory T cells, in gastric cancer. This finding may suggest that PET-CT could be of use as a non-invasive tool for monitoring the tumor microenvironment in patients with gastric cancer.

Prognostic significance of interim 18 F-fluorodeoxyglucose positron emission tomography-computed tomography volumetric parameters in metastatic or recurrent gastric cancer

AIM

To evaluate the prognostic role of interim analysis of 18F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET/CT) volumetric parameters in patients with recurrent or metastatic advanced gastric cancer (AGC) treated with fluoropyrimidine-based palliative chemotherapy.

METHODS

Forty-four patients who underwent baseline and interim PET/CT scanning during palliative chemotherapy were analyzed retrospectively. Initial and change of metabolic parameters (MP) - metabolic tumor volume (MTV), tumor lesion glycolysis (TLG) and maximum and mean standardized uptake values (SUV) were measured with PET/CT. Metabolic change was measured by ∆MP (%)  =  (MP_interim  - MP_initial )/MP _initial   ×  100. Independent t-test was employed to compare values of initial, interim and change of metabolic parameters between each response group. Log-rank test was employed for univariate analysis, and multivariate analysis was performed using the Cox proportional hazards regression model to determine independently significant prognostic factors.

RESULTS

Reduced percentage values of maximum and mean SUV on interim PET/CT and initial values of volumetric parameters (MTV and TLG) were significant predicting factors to response to fluoropyrimidine-based palliative chemotherapy. The decreased percentage values of metabolic parameters as well as maximum and mean SUV with receiver operating characteristic (ROC) curve determined cut-off points were significant prognostic factors for overall survival and progression-free survival in univariate and multivariate analyses.

CONCLUSION

Measurement of metabolic decrease of volumetric parameters by interim PET/CT analysis is useful to determine the prognosis of patients with recurrent or metastatic AGC.

PET/Computed Tomography and Precision Medicine: Gastric Cancer

Gastric cancer is a disease with low survival rates and high morbidity, requiring accurate and prompt diagnosis and treatment. Although limited in the evaluation of the primary tumor as such, the metabolic information of primary tumors in an ¹⁸F-FDG PET/CT study can assist in surgical and treatment planning and differentiating gastric cancers. It detects nodal disease with good specificity and positive predictive value, thus enabling appropriate therapy for individual patients. It provides valuable information about distant metastases, altering therapy decisions. It has reasonably good performance in detecting recurrent disease and in the follow-up of patients.

Prognostic value of pretreatment standardized uptake value of F-18-fluorodeoxyglucose PET in patients with gastric cancer: a meta-analysis

Background

F-18- fluorodeoxyglucose Positron emission tomography (¹⁸FDG-PET) has been widely used in clinical practice. However, the prognostic value of the pretreatment standardized uptake value (SUV) for patients with gastric cancer remains controversial.

Methods

Major databases were systematically searched. The quality of the included studies was assessed using the Newcastle–Ottawa scale; the PET protocols were also evaluated. The pooled hazard ratio (HR) for overall survival (OS) and recurrence-free survival (RFS) were used to estimate the effect size. Data from the included studies were analyzed using Review Manager Software version 5.2.

Results

Eight studies with 1080 patients were included. The pooled HR for OS of six studies including 672 patients was 1.72 (95% CI [1.28–2.3], p = 0.0004, I² = 0%), indicating that patients with high SUVs may have poor prognosis. The pooled HR for RFS was 1.70 (95% CI [1.20–2.39], p = 0.003, I² = 0%). Subgroup analysis based on the cutoff values determining method indicated that the receiver operating characteristic (ROC) method could better define the cutoff value. Subgroup analysis based on the therapeutic strategies used subsequently indicated the significant prognostic value of SUV.

Conclusion

In conclusion, our meta-analysis indicated that pretreatment SUV in primary lesions can be an important prognostic factor for overall survival and recurrence-free survival in patients with gastric cancer. High SUVs may indicate poor prognosis.

Low uptake of fluorodeoxyglucose in positron emission tomography/computed tomography in ovarian clear cell carcinoma may reflect glutaminolysis of its cancer stem cell-like properties

The characteristics of ovarian cancers that showed low activation of glycolysis were investigated. Using medical records of patients with ovarian cancers who had undergone fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) prior to their primary surgery at the University of Tokyo Hospital between 2010 and 2015, we identified cases with a low uptake of FDG in PET/CT. We considered the maximum standardized uptake value (SUVmax) as the degree of glucose uptake. We investigated the properties which may account for the low activation of glycolysis in vitro. The expression level of alanine, serine, cysteine-preferring transporter 2 (ASCT2, a glutamine influx transporter), system L-type amino acid transporter 1 (LAT1, a glutamine efflux transporter) and glucose transporter 1 (GLUT1, a glucose influx transporter) were investigated by western blotting. The phosphorylation level of AMP-activated protein kinase (AMPK), which is one of the metabolic sensors, was also investigated. Most of the cases with a low uptake SUVmax were limited to patients with ovarian clear cell carcinoma (CCC). We obtained cancer stem cell (CSC)-like properties from CCC cell lines, and compared the expression levels of transporters between non-CSCs and CSCs. Whereas the expression level of ASCT2 was nearly unchanged between non-CSCs and CSCs, the expression levels of LAT1 and GLUT1 were decreased in CSCs compared to non-CSCs. The phosphorylation level of AMPK was reduced in CSCs compared to non-CSCs. In conclusion, we suggested that ovarian CCC showed low activation of glycolysis, and this may reflect glutaminolysis of its CSC-like properties.

Predictive Role of the Number of 18F-FDG-Positive Lymph Nodes Detected by PET/CT for Pre-Treatment Evaluation of Locally Advanced Gastric Cancer

OBJECTIVES

The aim of this study was to investigate the predictive value of the numbers of metabolically positive lymph nodes (MPLN) detected by 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT) in patients with locally advanced gastric cancer (LAGC).

METHODS

We retrospectively analyzed the records of 50 patients with LAGC (stage T2-T4) who had undergone pre-operative PET/CT examination and laparotomy (total gastrectomy, n = 11; subtotal gastrectomy, n = 13; distal gastrectomy, n = 22; and bypass with gastrojejunstomy, n = 4). The numbers of MPLN were determined by combining visual observations with semi-quantitative measurements of the maximized standardized uptake value (SUVmax). Performance was investigated in terms of predicting post-surgical overall survival (OS).

RESULTS

The median post-surgical OS was 32.57 months (range 3.0-94 months). The numbers of MPLN were moderately correlated with the numbers of histological positive LN (r = 0.694, p = 0.001). In univariate analyses, the numbers of MPLN (≤ 2 vs. ≥3), PET/CT LN (positivity vs. negativity), SUVmax of LN (< 2.8 vs. ≥ 2.8), TNM stage (I, II vs. III, IV), and surgery type (R0 vs. non-R0) were significantly associated with OS. In multivariate analysis, surgery type (R0 vs. non-R0) and numbers of MPLN (≤ 2 vs. ≥ 3) were both independent factors for poor OS.

CONCLUSIONS

This explored study indicates that the number of MPLN could provide additional information for LAGC prognosis. Patients with MPLNs ≥ 3 may be at the risk of the more bad outcomes, and the further clinical trials are needed.

Neuroblastoma: MIBG Imaging and New Tracers

Neuroblastoma is an embryonic tumor of the peripheral sympathetic nervous system, and is metastatic or otherwise high risk for relapse in nearly 50% of cases, with a long-term survival of <40%. Therefore, exact staging with radiological and nuclear medicine imaging methods is crucial for finding the adequate therapeutic choice. The tumor cells express the norepinephrine transporter, which makes metaiodobenzylguanidine (MIBG), an analogue of norepinephrine, an ideal tumor-specific agent for imaging. On the contrary, MIBG imaging has several disadvantages such as limited spatial resolution, limited sensitivity in small lesions, need for two or even more acquisition sessions, and a delay between the start of the examination and result. Most of these limitations can be overcome with positron emission tomography (PET) using different radiotracers. Furthermore, for operative or biopsy planning, a combination with morphological imaging methods is indispensable. This article would discuss the therapeutic strategy for primary and follow-up diagnosis in neuroblastoma using MIBG scintigraphy and different new PET tracers as well as multimodality imaging.

The Predictive and Prognostic Value of Early Metabolic Response Assessed by Positron Emission Tomography in Advanced Gastric Cancer Treated with Chemotherapy

PURPOSE

To evaluate the feasibility of early metabolic change assessed by PET in predicting clinical response to chemotherapy and investigate its prognostic value in patients with advanced gastric cancer.

EXPERIMENTAL DESIGN

A total of 64 patients with advanced gastric cancer were prospectively enrolled and examined by PET with (18)F-fluorodeoxyglucose (FDG) and (18)F-fluoro-3'-deoxy-3'-L-fluorothymidine (FLT) at baseline and 14 days after treatment initiation. PET findings were analyzed for the correlation with best clinical response of patients, disease control status, and survival after identifying the threshold of metabolic change percentage by ROC analysis.

RESULTS

For FDG-PET, the total uptake value reduction percentage (δ-SUV) of 40% was the cut-off point with the maximum of sensitivity (70%) and specificity (83%) to predict clinical responding and that of prediction for disease control status was 30%, with the highest sensitivity (58%) and specificity (100%). The δ-SUV of FLT-PET played no predictive role for clinical response (AUC = 0.62; P= 0.134) and disease control (AUC = 0.66; P= 0.157). The univariate Cox regression analysis revealed no significant prognostic impact. FDG uptake reduction in liver metastases could predict both clinical response (P= 0.010) and disease control status (P= 0.002) at thresholds of 35% and 15%, respectively. Those with greater FDG uptake reduction in liver lesions had a longer overall survival (P= 0.004).

CONCLUSIONS

Early metabolic change in FDG-PET might be a predictive marker for response and disease control in advanced gastric cancer. Early FDG uptake change in liver metastases might be a useful prognostic factor and needs further exploration.

Prognostic value and clinical correlations of 18-fluorodeoxyglucose metabolism quantifiers in gastric cancer

AIM: To investigate the correlations of pre-treatment positron emission tomography-computer tomography (PET-CT) metabolic quantifiers with clinical data of unstratified gastric cancer (GC) patients.

METHODS: Forty PET-CT scans utilising 18-fluorodeoxyglucose in patients who received no prior treatment were analysed. Analysis involved measurements of maximum and mean standardised uptake volumes (SUV), coefficient of variation (COV), metabolic tumour volumes and total lesion glycolysis of different thresholds above which the tumor volumes were identified. The threshold values were: SUV absolute value of 2.5, 30% of SUVmax, 40% of SUVmax, and liver uptake-based (marked _2.5, ₃₀, ₄₀ and _liv, respectively). Clinical variables such as age, sex, clinical stage, performance index, weight loss, tumor histological type and grade, and CEA and CA19.9 levels were included in survival analysis. Patients received various treatment modalities appropriate to their disease stage and the outcome was defined by time to metastasis (TTM) and overall survival (OS). Clinical and metabolic parameters were evaluated by analysis of variance, receiver operating characteristics, univariate Kaplan-Meier, and multivariate Cox models. P < 0.05 was considered statistically significant.

RESULTS: Significant differences were observed between initially disseminated and non-disseminated patients in mean SUV (6.05 vs 4.13, P = 0.008), TLG_2.5 (802 cm³vs 226 cm³; P = 0.031), and TLG₃₀ (436 cm³vs 247 cm³, P = 0.018). Higher COV was associated with poor tumour differentiation (0.47 for G3 vs 0.28 for G1 and G2; P = 0.03). MTV_2.5 was positively correlated to patient weight loss (< 5%, 5%-10% and > 10%: 40.4 cm³vs 123.6 cm³vs 181.8 cm³, respectively, P = 0.003). In multivariate Cox analysis, TLG₃₀ was prognostic for OS (HR = 1.001, 95%CI: 1.0009-1.0017; P = 0.047) for the whole group of patients. In the same model yet only including patients without initial disease dissemination TLG₃₀ (HR = 1.009, 95%CI: 1.003-1.014; P = 0.004) and MTV_2.5 (HR = 1.02, 95%CI: 1.002-1.036; P = 0.025) were prognostic for OS; for TTM TLG₃₀ was the only significant prognostic variable (HR = 1.006, 95%CI: 1.001-1.012; P = 0.02).

CONCLUSION: PET-CT in GC may represent a valuable diagnostic and prognostic tool that requires further evaluation in highly standardised environments such as randomised clinical trials.

Appropriateness criteria of FDG PET/CT in oncology

(18)Fluorine-2-fluoro-2-Deoxy-d-glucose ((18)F-FDG) positron emission tomography/computerized tomography (PET/CT) is a well-established functional imaging method widely used in oncology. In this article, we have incorporated the various indications for (18)FDG PET/CT in oncology based on available evidence and current guidelines. Growing body of evidence for use of (18)FDG PET/CT in select tumors is also discussed. This article attempts to give the reader an overview of the appropriateness of using (18)F-FDG PET/CT in various malignancies.

Correlation of Primary Tumor FDG Uptake with Histopathologic Features of Advanced Gastric Cancer

PURPOSE

Histopathologic features could affect the FDG uptake of primary gastric cancer and detection rate on FDG PET/CT. The aim of this study was to evaluate the FDG uptake of primary gastric cancer by correlating it with the histopathologic features of the tumors.

METHODS

Fifty patients with locally advanced gastric adenocarcinoma who were referred for preoperative FDG-PET/CT scans were enrolled in this study. The detection rate of PET/CT and maximum standardized uptake values (SUVmax) of the primary tumor were compared using the WHO, Lauren, Ming and Borrmann classifications and tumor size and location.

RESULTS

In 45 of the 50 patients (90 %), the primary gastric tumors were detected by FDG PET/CT. On comparison using the WHO classification, the detection rate and SUVmax of the tubular type were significantly higher than those of the poorly cohesive type. On comparison using the Lauren and Ming classifications, the SUVmaxs of the intestinal type and expanding type were significantly higher than those of the diffuse and infiltrative type, respectively. On comparison using the Borrmann classification and tumor size and location, there was no significant difference in the detection rate and SUVmax of primary gastric tumors.

CONCLUSION

This study demonstrates that the poorly cohesive type according to the WHO classification, diffuse type according to the Lauren classification and infiltrative type according to the Ming classification have low FDG uptake in patients with locally advanced gastric carcinoma. Understanding the relationship between primary tumor FDG uptake and histopathologic features would be helpful in detecting the primary tumor by FDG PET/CT in patients with gastric cancer.

Imaging of Gastric Cancer Metabolism Using 18 F-FDG PET/CT

Aerobic glycolysis has been the most important hypothesis in cancer metabolism. It seems to be related to increased bioenergetic and biosynthetic needs in rapidly proliferating cancer cells. To this end, F-18 fluorodeoxyglucose (FDG), a glucose analog, became widely popular for the detection of malignancies combined with positron emission tomography/computed tomography (PET/CT). Although the potential roles of FDG PET/CT in primary tumor detection are not fully established, it seems to have a limited sensitivity in detecting early gastric cancer and mainly signet ring or non-solid types of advanced gastric cancer. In evaluating lymph node metastases, the location of lymph nodes and the degree of FDG uptake in primary tumors appear to be important factors affecting the diagnostic accuracy of PET/CT. In spite of the limited sensitivity, the high specificity of PET/CT for lymph node metastases may play an important role in changing the extent of lymphadenectomy or reducing futile laparotomies. For peritoneal metastases, PET/CT seems to have a poorer sensitivity but a better specificity than CT. The roles of PET/CT in the evaluation of other distant metastases are yet to be known. Studies including primary tumors with low FDG uptake or peritoneal recurrence seem suffer from poorer diagnostic performance for the detection of recurrent gastric cancer. There are only a few reports using FDG PET/CT to predict response to neoadjuvant or adjuvant chemotherapy. A complete metabolic response seems to be predictive of more favorable prognosis.

Metabolic information on staging FDG-PET-CT as a prognostic tool in the evaluation of 97 patients with gastric cancer

BACKGROUND AND OBJECTIVE

Gastric cancer remains a leading cause of malignancy-related mortality. Many patients with locally advanced disease succumb despite peri-operative chemotherapy and the survival benefit of chemotherapy for advanced disease is modest, suggesting that current staging is imperfect. The role of fluorine-18-2-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) in the staging of gastric cancer remains to be determined. This study aimed to determine, and compare with computerized tomography (CT), the association between FDG-PET uptake in the primary tumour and regional lymph nodes, and overall survival in patients with all stage gastric cancer.

METHODS

Patients with histologically confirmed gastric cancer (any stage) who, at diagnosis, had received a staging FDG-PET-CT at our institution between 2006 and 2011 were included. Records were retrospectively analysed. Patients with >50 % of tumour above the gastro-oesophageal junction or an active second malignancy were excluded.

RESULTS

97 patients were included in the analysis. Surgery with curative intent was performed in 68 patients. In univariate analysis, an association with overall survival was seen in patients who had FDG-PET-positive primary tumours (hazard ratio (HR) for death 3.33, 95 % confidence interval (95 % CI) 1.63-6.80, p = 0.001). FDG-PET lymph node positive (vs node negativity) was associated with inferior overall survival (HR 8.66, 95 % CI 4.59-16.37, p < 0.0001), and remained an independent predictor in the multivariate analysis. In contrast, positive lymphadenopathy identified on CT was not associated with overall survival (HR 1.34, 95 % CI 0.79-2.29, p = 0.82).

CONCLUSION

FDG-PET-positive tumours are associated with an inferior overall survival. In contrast to CT, FDG-PET-positive lymphadenopathy is associated with a decreased overall survival.

Pretreatment F-18 FDG PET/CT Parameters to Evaluate Progression-Free Survival in Gastric Cancer

PURPOSE

We performed this study to evaluate the predictive value of pretreatment F-18 FDG PET/CT for progression-free survival (PFS) in patients with gastric cancer.

METHODS

Of 321 patients with a diagnosis of gastric cancer, we retrospectively enrolled 97 patients (men:women = 61:36, age 59.8 ± 13.2 years), who underwent pretreatment F-18 fluoro-2-deoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT) from January 2009 to December 2009. Maximum standardized uptake value (SUVmax) was measured for each case with detectable primary lesions. In the remaining non-detectable cases, SUVmax was measured from the corresponding site seen on gastroduodenoscopy for analysis. In subgroup analysis, metabolic tumor volume (MTV) was measured in 50 patients with clearly distinguishable primary lesions. SUVmax, stage, depth of tumor invasion and presence of lymph node metastasis were analyzed in terms of PFS. Receiver operating characteristic (ROC) curves were used to find optimal cutoff values of SUVmax and MTV for disease progression. The relationship between SUVmax, MTV and PFS was analyzed using the Kaplan-Meier with log-rank test and Cox's proportional hazard regression methods.

RESULTS

Of 97 patients, 15 (15.5 %) had disease progression. The mean follow-up duration was 29.6 ± 10.2 months. The mean PFS of low SUVmax group (≤5.74) was significantly longer than that of the high SUVmax group (>5.74) (30.9 ± 8.0 vs 24.3 ± 13.6 months, p = 0.008). In univariate analysis, stage (I vs II, III, IV), depth of tumor invasion (T1 vs T2, T3, T4), presence of lymph node metastasis and SUVmax (>5.74 vs ≤5.74) were significantly associated with recurrence. In multivariate analysis, high SUVmax (>5.74) was the only poor prognostic factor for PFS (p = 0.002, HR 11.03, 95 % CI 2.48-49.05). Subgroup multivariate analysis revealed that high MTV (>16.42) was the only poor prognostic factor for PFS (p = 0.034, HR 3.59, 95 % CI 1.10-11.71).

CONCLUSION

In gastric cancer, SUVmax measured by pretreatment F-18 FDG PET/CT has a significant predictive value for PFS. In addition, if MTV is measurable, high MTV is an independent factor for disease progression.

The role of 18F-fluorodeoxyglucose positron emission tomography in differentiated thyroid cancer before surgery

The incidence of thyroid cancer in both men and women is increasing faster than that of any other cancer. Although positron emission tomography (PET) using (18)F-fluorodeoxyglucose (FDG) has received much attention, the use of FDG PET for the management of thyroid cancer is limited primarily to postoperative follow-up. However, it might have a role in selected, more aggressive pathologies, and so patients at a high risk of distant metastasis may benefit from PET before surgery. As less FDG-avid thyroid cancers may lower the diagnostic accuracy of PET in preoperative assessment, an understanding of FDG avidity is important for the evaluation of thyroid cancer. FDG avidity has been shown to be associated with tumor size, lymph node metastasis, and glucose transporter expression and differentiation. As PET is commonly used in clinical practice, the detection of incidentalomas by PET is increasing. However, incidentalomas detected by PET have a high risk of malignancy. Clinicians handling cytologically indeterminate nodules face a dilemma regarding a procedure for a definitive diagnosis, usually lobectomy. With 'nondiagnostic (ND)' fine-needle biopsy (FNA), PET has shown a negative predictive value (NPV) of 100%, which indicates that negative uptake in a ND FNA procedure accurately excludes malignancy. With 'atypia of undetermined significance' or 'follicular neoplasm', the sensitivity and NPV of PET are 84 and 88%. PET does not provide additional information for the preoperative assessment of thyroid cancer. However, factors associated with FDG positivity are related to a poor prognosis; therefore, FDG PET scans before surgery may facilitate the prediction of the prognosis of differentiated thyroid cancer.

[Impact of the standardized uptake value on the body trunk with truncation error of μ-map in the positron emission tomography/computed tomography: phantom studies]

PURPOSE

The aim of this study was evaluate to impact of standardized uptake value (SUV) on the body trunk with truncation error of μ-map for CT attenuation correction (CTAC) in whole-body 2-deoxy-2-[(18)F] fluoro-D-glucose ((18)F-FDG)-positron emission tomography (PET)/CT with use of anthropomorphic phantom.

METHODS

We used body phantom (2.5 MBq/l) including simulated tumor targets (11.25 MBq/l) and arm phantom. The CT scan was used with a field of view (FOV) of 50 cm. The μ-maps were created by assuming a state of the arm protruding from the FOV (Pmap). A 3D-PET scan with an emission time of 20 min was performed. The PET images were then reconstructed with CTAC, and with and without scatter correction. We evaluated the relationship to Pmap size and the count of simulated tumors and background (B.G.) in PET images which reconstructed the use of each Pmap, respectively.

RESULTS

The count of simulated tumor (large) with scatter correction was decreased to 1.3% (Pmap: 15 mm) and 8.8% (Pmap: 35 mm). Then, the count severe reduction was 86.9% in Pmap of 65 mm. The same trend was shown by simulated tumor (middle, small) and B.G. The count of the simulated tumor (large) without scatter correction decreased to 1.3% (Pmap: 15 mm), 6.4% (Pmap: 35 mm) and 13.1% (Pmap: 65 mm).

CONCLUSION

Truncation error by μ-map for CTAC in whole-body (18)F-PET/CT caused a decrease of the SUV on the body trunk used for attenuation and scatter correction in the PET images.