Prognostic value of volumetric parameters of (18)F-FDG PET in non-small-cell lung cancer: a meta-analysis

Prognostic value of 18F-FDG-PET/CT parameters in patients with pancreatic carcinoma: A systematic review and meta-analysis

BACKGROUND

The identification of pancreatic carcinoma (PC) patients with poor prognosis is a priority in clinical oncology because of their high 5-year mortality. However, the prognostic value of pretreatment F-fluorodeoxyglucose (F-FDG)- positron emission tomography (PET)/computed tomography (CT) parameters in PC patients is controversial and no consensus exists as to its predictive capability. This meta-analysis was performed to comprehensively explore the prognostic significance of F-FDG-PET/CT parameters in patients with pancreatic carcinoma.

METHODS

Extensive literature searches of the PubMed, Embase, Web of Science, and Cochrane Library databases were conducted to identify literature published until March 5, 2017. Comparative analyses of the pooled hazard ratios (HRs) for event-free survival (EFS) and overall survival (OS) were performed to assess their correlations with pretreatment maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG). Either the fixed- or the random-effects model was adopted, depending on the heterogeneity observed across studies. Subgroup and sensitivity analyses were performed to assess the robustness of the results.

RESULTS

Sixteen studies including 1146 patients were identified. The pooled HRs for the probability of EFS were 1.90 (95% confidential interval (CI): 1.48-2.45) for SUVmax, 1.76 (95% CI: 1.20-2.58) for MTV, and 1.81 (95% CI: 1.27-2.58) for TLG. The pooled HRs for the probability of OS were 1.21 (95% CI: 1.12-1.31) for SUVmax, 1.56 (95% CI: 1.13-2.16) for MTV, and 1.70 (95% CI: 1.25-2.30) for TLG. A slight publication bias was detected using Begg test. After adjustment using the trim and fill procedure, the corrected HRs were not significantly different. The results of the subgroup analyses by SUVmax, MTV, and TLG showed that these factors may have similar prognostic significance.

CONCLUSION

F-FDG-PET/CT parameters, such as SUVmax, MTV, and TLG, may be significant prognostic factors in patients with pancreatic carcinoma. F-FDG-PET/CT imaging could be a promising tool to provide prognostic information for these patients.

Risk-stratifying capacity of PET/CT metabolic tumor volume in stage IIIA non-small cell lung cancer

OBJECTIVES

Stage IIIA non-small cell lung cancer (NSCLC) is heterogeneous in tumor burden, and its treatment is variable. Whole-body metabolic tumor volume (MTVWB) has been shown to be an independent prognostic index for overall survival (OS). However, the potential of MTVWB to risk-stratify stage IIIA NSCLC has previously been unknown. If we can identify subgroups within the stage exhibiting significant OS differences using MTVWB, MTVWB may lead to adjustments in patients' risk profile evaluations and may, therefore, influence clinical decision making regarding treatment. We estimated the risk-stratifying capacity of MTVWB in stage IIIA by comparing OS of stratified stage IIIA with stage IIB and IIIB NSCLC.

METHODS

We performed a retrospective review of 330 patients with clinical stage IIB, IIIA, and IIIB NSCLC diagnosed between 2004 and 2014. The patients' clinical TNM stage, initial MTVWB, and long-term survival data were collected. Patients with TNM stage IIIA disease were stratified by MTVWB. The optimal MTVWB cutoff value for stage IIIA patients was calculated using sequential log-rank tests. Univariate and multivariate cox regression analyses and Kaplan-Meier OS analysis with log-rank tests were performed.

RESULTS

The optimal MTVWB cut-point was 29.2 mL for the risk-stratification of stage IIIA. We identified statistically significant differences in OS between stage IIB and IIIA patients (p < 0.01), between IIIA and IIIB patients (p < 0.01), and between the stage IIIA patients with low MTVWB (below 29.2 mL) and the stage IIIA patients with high MTVWB (above 29.2 mL) (p < 0.01). There was no OS difference between the low MTVWB stage IIIA and the cohort of stage IIB patients (p = 0.485), or between the high MTVWB stage IIIA patients and the cohort of stage IIIB patients (p = 0.459). Similar risk-stratification capacity of MTVWB was observed in a large range of cutoff values from 15 to 55 mL in stage IIIA patients.

CONCLUSIONS

Using MTVWB cutoff points ranging from 15 to 55 mL with an optimal value of 29.2 mL, stage IIIA NSCLC may be effectively stratified into subgroups with no significant survival difference from stages IIB or IIIB NSCLC. This may result in more accurate survival estimation and more appropriate risk adapted treatment selection in stage IIIA NSCLC.

Estimation of Recurrence Risk After Normal (18)F-FDG PET/CT in Nonsmall-Cell Lung Cancer

The authors aimed to assess the risk of recurrence in patients with nonsmall-cell lung cancer after surgery with no evidence of disease (NED) demonstrated on (18)F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT). A total of 140 subjects with adenocarcinoma or squamous cell carcinoma of the lung were included in this study. Patients had FDG PET/CT scans within a year after surgery between January 2007 and December 2014. Patients with PET/CT scans with NED were included. Following an NED PET/CT scan, recurrence or metastasis was found in 14 patients (10.0%), and deaths in 4 (2.9%) during a median follow-up of 636 days. Although the rates of recurrence or metastasis were very low, the risk for recurrence continuously increased after 600 days up to 0.03%. The risk was higher in patients with positive margin at surgery, lymphovascular invasion, N2 stage, and TNM stage III/IV. In conclusion, according to the smoothed hazard functions, there was a very low risk of recurrence until 600 days after normal (18)F-FDG PET scans. The risk was higher in patients with positive margin at surgery, lymphovascular invasion, N2 stage, and TNM stage III/IV.

Prognostic value of 18F-FDG PET-CT-based functional parameters in patients with soft tissue sarcoma: A meta-analysis

BACKGROUND

Considering the clinical importance of high 5-year mortality, we performed a meta-analysis of maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) from F-FDG PET-CT for overall survival (OS) and progression-free survival (PFS) in patients with soft tissue sarcoma.

METHODS

The search and selection of eligible articles was conducted on PubMed and EMBASE. We applied hazard ratio (HR) and odd ratio (OR) to measure the correlation between SUVmax, MTV, and TLG with PFS and OS. The SUVmax was analyzed through subgroup in terms of histological grade and HR of posttreatment SUVmax was also assessed.

RESULTS

Eleven studies with 582 patients were included. The pooled HRs of pretreatment SUVmax were 2.40 (95% CI: 1.38-4.17) for OS and 2.20 (95% CI: 1.47-3.30) for PFS. The HRs in terms of OS were 3.20 (95% CI: 1.71-5.98) based on MTV and 5.20 (95% CI: 2.34-11.56) based on TLG. Meanwhile, the predict results of pretreatment SUVmax on OR remained significant and the HRs of posttreatment SUVmax were 2.25 (95% CI: 1.33-3.80) for OS and 2.87 (95% CI: 1.81-4.55) for PFS.

CONCLUSIONS

The pretreatment SUVmax, MTV, and TLG of F-FDG PET-CT showed significant prognostic value for OS and the PET-CT can be used in identifying high-risk patients about progression and survival. The analysis for posttreatment SUVmax suggested PET-CT as a promising equipment in monitoring therapy response.

Role of Optimal Quantification of FDG PET Imaging in the Clinical Practice of Radiology

The combination of fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) and computed tomography (CT) for dual-modality imaging (PET/CT) plays a key role in the diagnosis and staging of FDG-avid malignancies. FDG uptake by the tumor cells offers an opportunity to detect cancer in organs that appear normal at anatomic imaging and to differentiate viable tumor from posttreatment effects. Quantification of FDG uptake has multiple clinical applications, including cancer diagnosis and staging. Dedicated FDG PET/CT-based visual and quantitative criteria have been developed to evaluate treatment response. Furthermore, the level of tumor FDG uptake reflects the biologic aggressiveness of the tumor, predicting the risk of metastasis and recurrence. FDG uptake can be measured with qualitative, semiquantitative, and quantitative methods. Qualitative or visual assessment of PET/CT images is the most common clinical approach for describing the level of FDG uptake. Standardized uptake value (SUV) is the most commonly used semiquantitative tool for measuring FDG uptake. SUV can be measured as maximum, mean, or peak SUV and may be normalized by using whole or lean body weight. SUV measurements provide the basis for quantitative response criteria; however, SUVs have not been widely adopted as diagnostic thresholds for discriminating malignant and benign lesions. Volumetric FDG uptake measurements such as metabolic tumor volume and total lesion glycolysis have shown substantial promise in providing accurate tumor assessment. SUV measurement and other quantification techniques can be affected by many technical, physical, and biologic factors. Familiarity with FDG uptake quantification approaches and their pitfalls is essential for clinical practice and research.

Prognostic Value of FDG Uptake of Portal Vein Tumor Thrombosis in Patients With Locally Advanced Hepatocellular Carcinoma

PURPOSE

This study aimed to evaluate the prognostic value of F-FDG uptake of portal vein tumor thrombosis (PVTT) for predicting progression-free survival (PFS) and overall survival (OS) in patients with locally advanced hepatocellular carcinoma (HCC).

METHODS

The study retrospectively included 166 HCC patients with PVTT and no extrahepatic metastases who underwent staging FDG PET/CT. Tumor-to-liver uptake ratio (TLR) and PVTT-to-liver uptake ratio (PLR) were measured for each patient, and the prognostic values of clinical factors, TLR, and PLR were assessed. Furthermore, patients were classified into 2 subgroups according to TLR, and the prognostic value of PLR was evaluated in each subgroup.

RESULTS

Median PFS and OS were 6.2 and 10.1 months, respectively. On multivariate analysis, tumor size (P = 0.006) and PLR (P = 0.03) were independent prognostic factors for PFS, whereas Child-Pugh class (P = 0.02) and PLR (P = 0.02) were independent prognostic factors for OS. Tumor-to-liver uptake ratio was a significant prognostic factor for PFS and OS on univariate analysis but failed to show significance on multivariate analysis. In both patient subgroups with low and high TLR, PLR remained a significant prognostic factor for predicting OS (P = 0.04 for all).

CONCLUSIONS

FDG uptake of PVTT, but not FDG uptake of HCC, is an independent prognostic factor for PFS and OS in HCC patients with PVTT and no extrahepatic metastasis. Given the prognostic significance, it is strongly encouraged to use FDG uptake of PVTT in further risk stratification for HCC patients with PVTT.

Prognostic Value of Tumor-to-Blood Standardized Uptake Ratio in Patients with Resectable Non-Small-Cell Lung Cancer

OBJECTIVES

Previously published studies showed that the standard tumor-to-blood standardized uptake value (SUV) ratio (SUR) was a more accurate prognostic method than tumor maximum standardized uptake value (SUV_max). This study evaluated and compared prognostic value of positron emission tomography (PET) parameters and normalized value of PET parameters by blood pool SUV in non-small-cell lung cancer (NSCLC) patients who received curative surgery.

METHODS

Seventy-seven patients who underwent curative resection for NSCLC between January 2010 to December 2013 were enrolled in this study. ¹⁸Fluorine-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) was performed before surgery. The mean standardized uptake value (SUV_mean), SUV_max, metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of each lesion was measured, on the workstation. SUR_mean, SUR_max, and TLGSUR were calculated by dividing each of them by descending aorta SUV_mean. Cox proportional hazards regression was used to analyze the effect of age, sex, pathological parameters, and PET parameters on recurrence and death.

RESULTS

In Cox regression analysis, N stage predicted for both recurrence (p < 0.0001) and death (p < 0.0001). SUR_max predicted recurrence (p = 0.0014), not death. Area under the receiver operating characteristic curve of SUR_max was 0.759 with cutoff value 4.004. However, SUV_max, SUV_mean, MTV, TLG, SUR_mean, and TLGSUR predicted neither recurrence nor death.

CONCLUSIONS

Among PET parameters, SUR_max was the independent predictor of recurrence in NSCLC patients who received curative surgery. N stage was the independent prognostic factor for both recurrence and death. Both parameters could be used to stratify the risk of NSCLC patients.

Prognostic value of tumoral heterogeneity and volumetric parameters as measured by F18-FDG PET/CT in sinonasal cancer

The objective of this study was to investigate the value of parameters assessed with F18-FDG PET/CT in predicting recurrence-free survival (RFS) and disease-specific survival (DSS) in patients with cancer of nasal cavity and paranasal sinus. Thirty-eight patients with cancer of nasal cavity (n = 14) and paranasal sinus (n = 24) who underwent PET/CT prior to curative treatment were enrolled. A volume of interest was placed on PET/CT images covering the entire tumor volume, and the maximum SUV (SUV_max), the mean SUV (SUV_mean), and volumetric parameters of metabolic tumor volume (MTV) and total lesion glycolysis (TLG) were measured using thresholds of 40 % of SUV_max. The heterogeneity factor (HF) defined as the derivative of volume-threshold function from 40 to 80 % of SUV thresholds. RFS and DSS were defined as the time from the diagnosis to recurrence and death. Median values of SUV_max, SUV_mean, MTV, TLG, and HF were 14.81, 9.16, 25.84, 150.74, and -0.496. SUV_max was higher in patients with advanced stage and nodal metastasis. High MTV and low HF group showed shorter RFS. Cox proportional hazards regression analysis revealed low HF was the only significant predictive factor on RFS. Furthermore, high TLG was associated with shorter DSS. High TLG was potent predictor of DSS by Cox proportional hazards regression analysis. In conclusion, the tumoral heterogeneity and volumetric parameters as measured by F18-FDG PET/CT could be significant prognostic surrogate markers in patients with sinonasal cancer.

Clinical Significance of Pretreatment FDG PET/CT in MIBG-Avid Pediatric Neuroblastoma

PURPOSE

¹⁸F-fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging is well known to have clinical significance in the initial staging and response evaluation of the many kinds of neoplasms. However, its role in the pediatric neuroblastoma is not clearly defined. In the present study, the clinical significance of FDG-PET/computed tomography (CT) in ¹²³I- or ¹³¹I-metaiodobenzylguanidine (MIBG)-avid pediatric neuroblastoma was investigated.

METHODS

Twenty patients with neuroblastoma who undertook pretreatment FDG PET/CT at our institute between 2008 and 2015 and showed MIBG avidity were retrospectively enrolled in the present study. Clinical information-including histopathology, and serum markers-and several PET parameters-including SUVmax of the primary lesion (Psuv), target-to-background ratio (TBR), metabolic tumor volume (MTV), and coefficient of variation (CV)-were analyzed. The prognostic effect of PET parameters was evaluated in terms of progression-free survival (PFS).

RESULTS

Total 20 patients (4.5 ± 3.5 years) were divided as two groups by disease progression. Six patients (30.0 %) experienced disease progression and one patient (5.0 %) died during follow-up period. There were not statistically significant in age, stage, MYCN status, primary tumor size, serum lactate dehydrogenase (LDH), neuron-specific enolase (NSE), and ferritin level between two groups with progression or no progression. However, Psuv (p = 0.017), TBR (p = 0.09), MTV (p = 0.02), and CV (p = 0.036) showed significant differences between two groups. In univariate analysis, PFS was significantly associated with Psuv (p = 0.021) and TBR (p = 0.023).

CONCLUSIONS

FDG-PET parameters were significantly related with progression of neuroblastoma. FDG-PET/CT may have the potential as a valuable modality for evaluating prognosis in the patients with MIBG-avid pediatric neuroblastoma.

18F-fluorodeoxyglucose positron emission tomography/computed tomography comparison of gastric lymphoma and gastric carcinoma

AIM

To compare ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) features in gastric lymphoma and gastric carcinoma.

METHODS

Patients with newly diagnosed gastric lymphoma or gastric carcinoma who underwent ¹⁸F-FDG PET/CT prior to treatment were included in this study. We reviewed and analyzed the PET/CT features of gastric wall lesions, including FDG avidity, pattern (focal/diffuse), and intensity [maximal standard uptake value: (SUVmax)]. The correlation of SUVmax with gastric clinicopathological variables was investigated by χ² test, and receiver-operating characteristic (ROC) curve analysis was performed to determine the differential diagnostic value of SUVmax-associated parameters in gastric lymphoma and gastric carcinoma.

RESULTS

Fifty-two patients with gastric lymphoma and 73 with gastric carcinoma were included in this study. Abnormal gastric FDG accumulation was found in 49 patients (94.23%) with gastric lymphoma and 65 patients (89.04%) with gastric carcinoma. Gastric lymphoma patients predominantly presented with type I and type II lesions, whereas gastric carcinoma patients mainly had type III lesions. The SUVmax (13.39 ± 9.24 vs 8.35 ± 5.80, P < 0.001) and SUVmax/THKmax (maximal thickness) (7.96 ± 4.02 vs 4.88 ± 3.32, P < 0.001) were both higher in patients with gastric lymphoma compared with gastric carcinoma. ROC curve analysis suggested a better performance of SUVmax/THKmax in the evaluation of gastric lesions between gastric lymphoma and gastric carcinoma in comparison with that of SUVmax alone.

CONCLUSION

PET/CT features differ between gastric lymphoma and carcinoma, which can improve PET/CT evaluation of gastric wall lesions and help differentiate gastric lymphoma from gastric carcinoma.

The role of 18F-fluorodeoxyglucose uptake of bone marrow on PET/CT in predicting clinical outcomes in non-small cell lung cancer patients treated with chemoradiotherapy

OBJECTIVES

This study aimed to assess the relationship between bone marrow (BM) FDG uptake on PET/CT and serum inflammatory markers and to evaluate the prognostic value of BM FDG uptake for predicting clinical outcomes in non-small cell lung cancer (NSCLC) patients.

METHODS

One hundred and six NSCLC patients who underwent FDG PET/CT for staging work-up and received chemoradiotherapy were enrolled. Mean BM FDG uptake (BM SUV) and BM-to-liver uptake ratio (BLR) were measured, along with volumetric parameters of PET/CT. The relationship of BM SUV and BLR with hematologic parameters and serum inflammatory markers was evaluated. Prognostic values of BM SUV and BLR for predicting progression-free survival (PFS) and overall survival (OS) were assessed.

RESULTS

BM SUV and BLR were significantly correlated with white blood cell count and C-reactive protein level. On univariate analysis, BLR was a significant prognostic factor for both PFS and OS. On multivariate analysis, TNM stage and BLR were independent prognostic factors for PFS, and only TNM stage was an independent prognostic factor for OS.

CONCLUSIONS

In NSCLC patients, FDG uptake of BM reflects the systemic inflammatory response and can be used as a biomarker to identify patients with poor prognosis.

KEY POINTS

• Bone marrow FDG uptake is correlated with serum inflammatory markers. • Bone marrow FDG uptake is an independent prognostic factor for progression-free survival. • Bone marrow FDG uptake can provide information on predicting lung cancer progression.

Prognostic value of early response assessment using 18F-FDG PET/CT in chemotherapy-treated patients with non-small-cell lung cancer

OBJECTIVE

We aimed to evaluate the prognostic value of early response assessment using a volumetric fluorine-18-fluorodeoxyglucose (F-FDG) PET analysis in chemotherapy-treated patients with non-small-cell lung cancer (NSCLC).

MATERIALS AND METHODS

We retrospectively reviewed 33 patients with NSCLC who received first-line chemotherapy and performed F-FDG PET/computed tomography before (baseline PET) and after two cycles of chemotherapy (interim PET). The maximum standardized uptake value (SUVmax) and metabolic tumor volume (MTV) of the total malignant lesion were measured in baseline (SUV1 and MTV1) and interim (SUV2 and MTV2) PET images, and percentage changes in SUVmax (ΔSUV) and MTV (ΔMTV) were calculated between the two images. We compared PET parameters and clinicopathologic variables in terms of the 2-year overall survival (OS).

RESULTS

The median follow-up period was 14.3 months and the 2-year OS was 31%. In PET images, the mean SUV1, MTV1, SUV2, MTV2, ΔSUV, and ΔMTV were 13.1±4.5, 307.9±340.0 cm, 9.5±5.1, 180.4±29.6 cm, 27±28%, and 42±65%, respectively. In univariable analysis, M stage, TNM stage, and all six PET parameters associated significantly with OS. Both the MTV1 and the ΔMTV were tested against OS controlling for M stage, one at time, and the effect remained significant in multivariable analyses.

CONCLUSION

A smaller baseline MTV and greater decrease in MTV between baseline and interim PET images are associated with a significantly prolonged OS. A volume-based F-FDG PET analysis would facilitate prediction of clinical outcome and identification of treatment-resistant patients early during chemotherapy and could thus be used in personalized treatment approaches for patients with NSCLC.

The Impact of Optimal Respiratory Gating and Image Noise on Evaluation of Intratumor Heterogeneity on 18F-FDG PET Imaging of Lung Cancer

Accurate measurement of intratumor heterogeneity using parameters of texture on PET images is essential for precise characterization of cancer lesions. In this study, we investigated the influence of respiratory motion and varying noise levels on quantification of textural parameters in patients with lung cancer.

METHODS

We used an optimal-respiratory-gating algorithm on the list-mode data of 60 lung cancer patients who underwent ¹⁸F-FDG PET. The images were reconstructed using a duty cycle of 35% (percentage of the total acquired PET data). In addition, nongated images of varying statistical quality (using 35% and 100% of the PET data) were reconstructed to investigate the effects of image noise. Several global image-derived indices and textural parameters (entropy, high-intensity emphasis, zone percentage, and dissimilarity) that have been associated with patient outcome were calculated. The clinical impact of optimal respiratory gating and image noise on assessment of intratumor heterogeneity was evaluated using Cox regression models, with overall survival as the outcome measure. The threshold for statistical significance was adjusted for multiple comparisons using Bonferroni correction.

RESULTS

In the lower lung lobes, respiratory motion significantly affected quantification of intratumor heterogeneity for all textural parameters (P < 0.007) except entropy (P > 0.007). The mean increase in entropy, dissimilarity, zone percentage, and high-intensity emphasis was 1.3% ± 1.5% (P = 0.02), 11.6% ± 11.8% (P = 0.006), 2.3% ± 2.2% (P = 0.002), and 16.8% ± 17.2% (P = 0.006), respectively. No significant differences were observed for lesions in the upper lung lobes (P > 0.007). Differences in the statistical quality of the PET images affected the textural parameters less than respiratory motion, with no significant difference observed. The median follow-up time was 35 mo (range, 7-39 mo). In multivariate analysis for overall survival, total lesion glycolysis and high-intensity emphasis were the two most relevant image-derived indices and were considered to be independent significant covariates for the model regardless of the image type considered.

CONCLUSION

The tested textural parameters are robust in the presence of respiratory motion artifacts and varying levels of image noise.

Performance of automatic image segmentation algorithms for calculating total lesion glycolysis for early response monitoring in non-small cell lung cancer patients during concomitant chemoradiotherapy

BACKGROUND AND PURPOSE

This study evaluated the use of total lesion glycolysis (TLG) determined by different automatic segmentation algorithms, for early response monitoring in non-small cell lung cancer (NSCLC) patients during concomitant chemoradiotherapy.

MATERIALS AND METHODS

Twenty-seven patients with locally advanced NSCLC treated with concomitant chemoradiotherapy underwent (18)F-fluorodeoxyglucose (FDG) PET/CT imaging before and in the second week of treatment. Segmentation of the primary tumours and lymph nodes was performed using fixed threshold segmentation at (i) 40% SUVmax (T40), (ii) 50% SUVmax (T50), (iii) relative-threshold-level (RTL), (iv) signal-to-background ratio (SBR), and (v) fuzzy locally adaptive Bayesian (FLAB) segmentation. Association of primary tumour TLG (TLGT), lymph node TLG (TLGLN), summed TLG (TLGS=TLGT+TLGLN), and relative TLG decrease (ΔTLG) with overall-survival (OS) and progression-free survival (PFS) was determined using univariate Cox regression models.

RESULTS

Pretreatment TLGT was predictive for PFS and OS, irrespective of the segmentation method used. Inclusion of TLGLN improved disease and early response assessment, with pretreatment TLGS more strongly associated with PFS and OS than TLGT for all segmentation algorithms. This was also the case for ΔTLGS, which was significantly associated with PFS and OS, with the exception of RTL and T40.

CONCLUSIONS

ΔTLGS was significantly associated with PFS and OS, except for RTL and T40. Inclusion of TLGLN improves early treatment response monitoring during concomitant chemoradiotherapy with FDG-PET.

Prognostic Value of Metabolic and Volumetric Parameters of Preoperative FDG-PET/CT in Patients With Resectable Pancreatic Cancer

In this study, we aimed to evaluate prognostic value of metabolic and volumetric parameters measured from F fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) in patients with resectable pancreatic cancer.Fifty-one patients with resectable pancreatic cancer who underwent FDG-PET/CT and curative operation were retrospectively enrolled. The maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were measured from FDG-PET/CT. Association between FDG-PET/CT and clinicopathologic parameters was evaluated. The prognostic values of the FDG-PET/CT and clinicopathologic parameters for recurrence-free survival (RFS) and overall survival (OS) were assessed by univariate and multivariate analyses.The 51 enrolled patients were followed up for a median of 21 months (mean ± SD: 23 ± 16 months, range: 1-78 months) with 33 (65%) recurrences and 30 (59%) deaths during the period. SUVmax, MTV, and TLG were associated with Tumor node metastasis (TNM) stage and presence of lymph node metastasis. MTV and TLG were associated with presence of lymphovascular invasion, whereas SUVmax was not. On the univariate analysis, SUVmax, MTV, and TLG were associated with RFS and OS. Also, lymph node metastasis and TNM stage were associated with OS on the univariate analysis. On multivariate analysis, MTV and TLG were independent prognostic factors for RFS and OS. SUVmax was an independent prognostic factor for OS, but not for RFS.Metabolic tumor volume and TLG were independently predictive of RFS and OS in resectable pancreatic cancer. SUVmax was an independent factor for OS, but not for RFS.

Present and future roles of FDG-PET/CT imaging in the management of lung cancer

Integrated positron emission tomography/computed tomography (PET/CT) using 2-[(18)F]fluoro-2-deoxy-D-glucose ((18)F-FDG) has emerged as a powerful tool for combined metabolic and anatomic evaluation in clinical oncologic imaging. This review discusses the utility of (18)F-FDG PET/CT as a tool for managing patients with lung cancer. We discuss different patient management stages, including diagnosis, initial staging, therapy planning, early treatment response assessment, re-staging, and prognosis.

Update on F-18-fluoro-deoxy-glucose-PET/computed tomography in nonsmall cell lung cancer

PURPOSE OF REVIEW

The aim of this review is to provide an outline of current evidence for the use of F-18-fluoro-deoxy-glucose PET computed tomography (FDG-PET/CT) in nonsmall cell lung cancer (NSCLC) for diagnosis, staging, radiotherapy planning, response assessment and response monitoring.

RECENT FINDINGS

Management of patients with NSCLC requires a multimodality approach to accurately diagnose and stage patients. In this approach, FDG-PET/CT has become a standard staging instrument in lung cancer. FDG-PET/CT is, in addition to staging, also valuable for the characterization of the solitary pulmonary nodule. An increased uptake in the nodule as compared with mediastinal blood pool is suspected for malignancy. In radiotherapy planning, FDG-PET/CT can assist the radiation oncologist for optimal dose delivery to the tumour, while sparing healthy tissues. Evidence of the prognostic and predictive implications of FDG-PET/CT is accumulating. Volumetric parameters of PET, such as metabolic active tumour volume and total lesion glycolysis, are promising predictive and prognostic biomarkers. However, for implementation of metabolic response parameters in clinical practice, more randomized, PET-based, multicentre trials are necessary. The introduction of integrated PET and MRI scanners did not change the pivotal role of standard FDG-PET/CT yet, as with current technology, PET/MRI did not show superior performance in thoracic staging.

SUMMARY

The role of PET is described for diagnosis, staging and response assessment.

Prognostic value of (18)F-fluorodeoxyglucose positron emission tomography in patients with gastric neuroendocrine carcinoma and mixed adenoneuroendocrine carcinoma

OBJECTIVE

Gastric neuroendocrine carcinomas (NEC) and mixed adenoneuroendocrine carcinoma (MANEC) are very rare, aggressive tumors of the stomach. We aimed to examine predictive role of pretreatment (18)F-FDG PET/CT-assessed metabolic parameter of primary tumors and metastases in patients with gastric NEC and MANEC.

METHODS

We conducted a review of the 27 patients with histopathologically confirmed NECs (n = 10) and MANEC (n = 17) of the stomach at our institution between January 2005 and December 2012. All patients underwent (18)F-FDG-PET examination at diagnosis. Metabolic parameters [SUVmax, SUVmean, metabolic tumor volume (MTV) and total lesion glycolysis (TLG)] of the primary tumor and metastases on baseline PET/CT were analyzed.

RESULTS

The median follow-up duration was 39.4 months (95 % CI 20.0-58.1 months) and the median overall survival (OS) was 25.7 months (95 % CI 14.1-37.2 months). All gastric lesions were well visualized (average SUVmax = 12.0, range 3.0-41.8). When subjects were divided into two groups by ROC cut-off value of 210.9 and 612, patients with high TLG in primary lesion and metastases showed poorer prognosis compared to low TLG patients (P = 0.09, P = 0.002, respectively). In the sub-analysis of patients with metastasis (n = 12), patients with high TLG in whole body tumor showed significantly shorter OS compared to those with low TLG (31.7 ± 11.4 vs. 7.2 ± 2.1 months, P = 0.006).

CONCLUSION

(18)F-FDG PET/CT is useful in evaluating prognosis of advanced gastric cancer with neuroendocrine carcinoma components. Baseline MTV of primary gastric cancer with metastatic disease, and MTV, TLG of metastases may be prognostic markers in patients with gastric NEC and MANEC.

Prognostic Value of 18F-FDG PET/CT in Surgical Non-Small Cell Lung Cancer: A Meta-Analysis

Background

The identification of surgical non-small cell lung cancer (NSCLC) patients with poor prognosis is a priority in clinical oncology because of their high 5-year mortality. This meta-analysis explored the prognostic value of maximal standardized uptake value (SUV_max), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) on disease-free survival (DFS) and overall survival (OS) in surgical NSCLC patients.

Materials and Methods

MEDLINE, EMBASE and Cochrane Libraries were systematically searched until August 1, 2015. Prospective or retrospective studies that evaluated the prognostic roles of preoperative 18F-FDG PET/CT with complete DFS and OS data in surgical NSCLC patients were included. The impact of SUV_max, MTV or TLG on survival was measured using hazard ratios (HR). Sub-group analyses were performed based on disease stage, pathological classification, surgery only and cut-off values.

Results

Thirty-six studies comprised of 5807 patients were included. The combined HRs for DFS were 2.74 (95%CI 2.33–3.24, unadjusted) and 2.43 (95%CI: 1.76–3.36, adjusted) for SUV_max, 2.27 (95%CI 1.77–2.90, unadjusted) and 2.49 (95%CI 1.23–5.04, adjusted) for MTV, and 2.46 (95%CI 1.91–3.17, unadjusted) and 2.97 (95%CI 1.68–5.28, adjusted) for TLG. The pooled HRs for OS were 2.54 (95%CI 1.86–3.49, unadjusted) and 1.52 (95%CI 1.16–2.00, adjusted) for SUV_max, 2.07 (95%CI 1.16–3.69, unadjusted) and 1.91 (95%CI 1.13–3.22, adjusted) for MTV, and 2.47 (95%CI 1.38–4.43, unadjusted) and 1.94 (95%CI 1.12–3.33, adjusted) for TLG. Begg’s test detected publication bias, the trim and fill procedure was performed, and similar HRs were obtained. The prognostic role of SUV_max, MTV and TLG remained similar in the sub-group analyses.

Conclusions

High values of SUV_max, MTV and TLG predicted a higher risk of recurrence or death in patients with surgical NSCLC. We suggest the use of FDG PET/CT to select patients who are at high risk of disease recurrence or death and may benefit from aggressive treatments.

Volume-Based Assessment With 18F-FDG PET/CT Improves Outcome Prediction for Patients With Stage IIIA-N2 Non-Small Cell Lung Cancer

OBJECTIVE

We evaluated the prognostic impact of volume-based assessment by pretreatment (18)F-FDG PET/CT in patients who had clinical stage IIIA-N2 non-small cell lung cancer (NSCLC) treated with neoadjuvant concurrent chemoradiotherapy (CCRT) followed by surgical resection.

MATERIALS AND METHODS

We reviewed 161 consecutive patients who had stage IIIA-N2 NSCLC treated with neoadjuvant CCRT followed by surgery. In all cases, N2 disease was pathologically confirmed by mediastinoscopic biopsy, endobronchial ultrasound-guided transbronchial needle aspiration, or video-assisted thoracoscopic surgery. We measured the total metabolic tumor volume (total MTV) and the maximum standardized uptake value (SUVmax), including a primary tumor and metastatic nodes on the pretreatment scan. Overall survival (OS) and disease-free survival (DFS) were assessed using the Kaplan-Meier method. The association of PET parameters with OS and DFS was determined by univariable and multivariable analyses performed using the Cox regression model.

RESULTS

A higher total MTV was significantly associated with poor DFS (hazard ratio [HR], 1.82; p = 0.036) and OS (HR = 2.97; p = 0.012) in the multivariable analysis. In contrast, a higher SUVmax was not significantly associated with poor DFS and OS. Patients with a high total MTV (> 22 cm(3)) had a median survival time that was significantly shorter than that of patients with a low total MTV (median DFS, 11.3 vs 42.0 months, respectively [p < 0.001]; median OS, 38.3 months vs not reached [p < 0.001]). Kaplan-Meier curves showed significant differences on the basis of total MTV in patients with or without mediastinal downstaging after CCRT. Patients with a high total MTV had significantly worse DFS when they had post-neoadjuvant pathologic (yp) stage 0-II disease (p = 0.020) or yp stage III disease (p = 0.036). Higher total MTV was also associated with worse OS in patients with yp stage 0-II disease (p = 0.013) or yp stage III disease (p = 0.007).

CONCLUSION

A higher pretreatment total MTV is associated with worse outcome, independent of yp stage, in patients with stage IIIA-N2 NSCLC treated with neoadjuvant CCRT followed by surgery.

Fluorodeoxyglucose Uptake on Positron Emission Tomography Is a Useful Predictor of Long-Term Pain Control After Palliative Radiation Therapy in Patients With Painful Bone Metastases: Results of a Single-Institute Prospective Study

PURPOSE

To determine whether fluorodeoxyglucose positron emission tomography (FDG-PET) before and after palliative radiation therapy (RT) can predict long-term pain control in patients with painful bone metastases.

METHODS AND MATERIALS

Thirty-one patients with bone metastases who received RT were prospectively included. Forty painful metastatic treatment fields were evaluated. All patients had undergone pre-RT and post-RT PET/CT scanning. We evaluated the relationships between the pre-RT, post-RT, and changes in maximum standardized uptake value (SUVmax) and the pain response, and between SUVmax and pain relapse of the bone metastases in the treatment field. In addition, we compared the SUVmax according to the length of time from the completion of RT to pain relapse of the bone metastases.

RESULTS

Regarding the pain response at 4 weeks after the completion of RT, there were 36 lesions of 27 patients in the responder group and 4 lesions of 4 patients in the nonresponder group. Changes in the SUVmax differed significantly between the responder and nonresponder groups in both the early and delayed phases (P=.0292 and P=.0139, respectively), but no relationship was observed between the pre-RT and post-RT SUVmax relative to the pain response. The responder group was evaluated for the rate of relapse. Thirty-five lesions of 26 patients in the responder group were evaluated, because 1 patient died of acute renal failure at 2 months after RT. Twelve lesions (34%) showed pain relapse, and 23 lesions (66%) did not. There were significant differences between the relapse and nonrelapse patients in terms of the pre-RT (early/delayed phases: P<.0001/P<.0001), post-RT (P=.0199/P=.0261), and changes in SUVmax (P=.0004/P=.004).

CONCLUSIONS

FDG-PET may help predict the outcome of pain control in the treatment field after palliative RT for painful bone metastases.

[Positron emission tomography and stereotactic body radiation therapy for lung cancer: From treatment planning to response evaluation]

Stereotactic body radiation therapy is the standard treatment for inoperable patients with early-stage lung cancer. Local control rates range from 80 to 90 % 2 years after treatment. The role of positron emission tomography in patient selection is well known, but its use for target definition or therapeutic response evaluation is less clear. We reviewed the literature in order to assess the current state of knowledge in this area.

Prognostic value of (18) F-fluoroazomycin arabinoside PET/CT in patients with advanced non-small-cell lung cancer

This study evaluated the prognostic value of positron emission tomography/computed tomography (PET/CT) using ¹⁸F‐fluoroazomycin arabinoside (FAZA) in patients with advanced non‐small‐cell lung cancer (NSCLC) compared with ¹⁸F‐fluorodeoxyglucose (FDG). Thirty‐eight patients with advanced NSCLC (stage III, 23 patients; stage IV, 15 patients) underwent FAZA and FDG PET/CT before treatment. The PET parameters (tumor‐to‐muscle ratio [T/M] at 1 and 2 h for FAZA, maximum standardized uptake value for FDG) in the primary lesion and lymph node (LN) metastasis and clinical parameters were compared concerning their effects on progression‐free survival (PFS) and overall survival (OS). In our univariate analysis of all patients, clinical stage and FAZA T/M in LNs at 1 and 2 h were predictive of PFS (P = 0.021, 0.028, and 0.002, respectively). Multivariate analysis also indicated that clinical stage and FAZA T/M in LNs at 1 and 2 h were independent predictors of PFS. Subgroup analysis of chemoradiotherapy‐treated stage III patients revealed that only FAZA T/M in LNs at 2 h was predictive of PFS (P = 0.025). The FDG PET/CT parameters were not predictive of PFS. No parameter was a significant predictor of OS. In patients with advanced NSCLC, FAZA uptake in LNs, but not in primary lesions, was predictive of treatment outcome. These results suggest the importance of characterization of LN metastases in advanced NSCLC patients.

Use of FDG PET/CT in Patients with Pancoast Tumors: Does It Add Any Contribution to Patient Management?

PURPOSE

To evaluate any potential value of 2-deoxy-2-[18F] fluoro-D-glucose with positron emission tomography/computerized tomography (FDG PET/CT) in staging of patients with Pancoast tumors and to investigate the relationship between volume-based quantitative PET parameters and prognosis.

MATERIALS AND METHODS

The authors retrospectively reviewed data of the 47 patients with Pancoast tumors who underwent initial staging by conventional imaging methods and FDG PET/CT. FDG-PET images were visually and quantitatively evaluated, and metabolic tumor volume (MTV), total lesion glycolysis, and maximum standardized uptake values of primary tumors were calculated. The correlations between quantitative PET parameters and tumor stages, as well as overall survival, were analyzed.

RESULTS

By detecting unknown distant metastasis, PET/CT upstaged 21% of patients. The sensitivity and specificity for detection of lymphatic involvement were 100% and 83.75%, respectively. Having surgery (p = 0.01) and being at an early stage (p = 0.004) were the most predictive factors for overall survival. Although there was no significant correlation between quantitative PET parameters and overall survival, MTV was the most powerful discriminator for operability and preoperative staging (p < 0.05).

CONCLUSIONS

FDG-PET imaging was found to be a valuable method for an accurate staging in the management of patients with Pancoast tumor. Having surgery and being at an early stage at presentation were found to be significant predictors for survival. Quantitative metabolic parameters may contribute to clarification of operable patient subgroups having an early disease stage with low MTV.

Prognostic Value of Metabolic Tumor Volume on (11)C-Methionine PET in Predicting Progression-Free Survival in High-Grade Glioma

PURPOSE

C-11 methionine (MET) PET is commonly used for diagnosing high-grade glioma (HGG). Recently, volumetric analysis has been widely applied to oncologic PET imaging. In this study, we investigated the prognostic value of metabolic tumor volume (MTV) on MET PET in HGG.

METHODS

A total of 30 patients with anaplastic astrocytoma (n = 12) and glioblastoma multiforme (n = 18) who underwent MET PET before treatment (surgery followed by chemo-radiotherapy) were retrospectively enrolled. Maximal tumor-to-normal brain ratio (TNRmax, maximum tumor activity divided by mean of normal tissue) and MTV (volume of tumor tissue that shows uptake >1.3-fold of mean uptake in normal tissue) were measured on MET PET. Adult patients were classified into two subgroups according to Radiation Therapy Oncology Group Recursive Partitioning Analysis (RTOG RPA) classification. Prognostic values of TNRmax, MTV and clinicopathologic factors were evaluated with regard to progression-free survival (PFS).

RESULTS

Median PFS of all patients was 7.9 months (range 1.0-53.8 months). In univariate analysis, MTV (cutoff 35 cm(3)) was a significant prognostic factor for PFS (P = 0.01), whereas TNRmax (cutoff 3.3) and RTOG RPA class were not (P = 0.80 and 0.61, respectively). Treatment of surgical resection exhibited a borderline significance (P = 0.06). In multivariate analysis, MTV was the only independent prognostic factor for PFS (P = 0.03).

CONCLUSION

MTV on MET PET is a significant and independent prognostic factor for PFS in HGG patients, whereas TNRmax is not. Thus, performing volumetric analysis of MET PET is recommended in HGG for better prognostication.

Stage III Non-Small Cell Lung Cancer: Prognostic Value of FDG PET Quantitative Imaging Features Combined with Clinical Prognostic Factors

PURPOSE

To determine whether quantitative imaging features from pretreatment positron emission tomography (PET) can enhance patient overall survival risk stratification beyond what can be achieved with conventional prognostic factors in patients with stage III non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

The institutional review board approved this retrospective chart review study and waived the requirement to obtain informed consent. The authors retrospectively identified 195 patients with stage III NSCLC treated definitively with radiation therapy between January 2008 and January 2013. All patients underwent pretreatment PET/computed tomography before treatment. Conventional PET metrics, along with histogram, shape and volume, and co-occurrence matrix features, were extracted. Linear predictors of overall survival were developed from leave-one-out cross-validation. Predictive Kaplan-Meier curves were used to compare the linear predictors with both quantitative imaging features and conventional prognostic factors to those generated with conventional prognostic factors alone. The Harrell concordance index was used to quantify the discriminatory power of the linear predictors for survival differences of at least 0, 6, 12, 18, and 24 months. Models were generated with features present in more than 50% of the cross-validation folds.

RESULTS

Linear predictors of overall survival generated with both quantitative imaging features and conventional prognostic factors demonstrated improved risk stratification compared with those generated with conventional prognostic factors alone in terms of log-rank statistic (P = .18 vs P = .0001, respectively) and concordance index (0.62 vs 0.58, respectively). The use of quantitative imaging features selected during cross-validation improved the model using conventional prognostic factors alone (P = .007). Disease solidity and primary tumor energy from the co-occurrence matrix were found to be selected in all folds of cross-validation.

CONCLUSION

Pretreatment PET features were associated with overall survival when adjusting for conventional prognostic factors in patients with stage III NSCLC.

A new PET/CT volumetric prognostic index for non-small cell lung cancer

OBJECTIVES

Whole-body metabolic tumor volume (MTVWB) has been shown of prognostic value for non-small cell lung cancer (NSCLC) beyond that of TNM stage, age, gender, performance status, and treatment selection. The current TNM staging system does not incorporate tumor volumetric information. We propose a new PET/CT volumetric prognostic (PVP) index that combines the prognostic value of MTVWB and TNM stage.

MATERIALS AND METHODS

Based on 328 consecutive NSCLC patients with a baseline PET/CT scan before treatment, from which MTVWB was measured semi-automatically, we estimated hazard ratios (HRs) for ln(MTVWB) and TNM stage from a Cox proportional hazard regression model that consisted of only ln(MTVWB) and TNM stage as prognostic variables of overall survival. We used the regression coefficients, which gave rise to the HRs, as weights to formulate the PET/CT volumetric prognostic (PVP) index. We also compared the prognostic value of the PVP index against that of TNM stage alone and ln(MTVWB) alone with univariate and multivariate survival analyses and C-statistics.

RESULTS

Univariate analysis C-statistic for the PVP index (C=0.71) was statistically significantly greater than those for TNM stage alone (C=0.67, p<0.01) and for ln(MTVWB) alone (C=0.69, p=0.033). Multivariate analyses showed that the PVP index yielded significantly greater discriminatory power (C=0.74) than similar models based on either TNM stage (C=0.72, p<0.01) or ln(MTVWB) (C=0.73, p<0.01). Lower values of the PVP index were associated with significantly better overall survival (adjusted HR=2.70, 95%CI [2.16, 3.37]).

CONCLUSION

The PVP index provides a practical means for clinicians to combine the prognostic value of MTVWB and TNM stage and offers significantly better prognostic accuracy for overall survival of NSCLC patients than the current TNM staging system or metabolic tumor burden alone.

Cancer stratification by molecular imaging

The lack of specificity of traditional cytotoxic drugs has triggered the development of anticancer agents that selectively address specific molecular targets. An intrinsic property of these specialized drugs is their limited applicability for specific patient subgroups. Consequently, the generation of information about tumor characteristics is the key to exploit the potential of these drugs. Currently, cancer stratification relies on three approaches: Gene expression analysis and cancer proteomics, immunohistochemistry and molecular imaging. In order to enable the precise localization of functionally expressed targets, molecular imaging combines highly selective biomarkers and intense signal sources. Thus, cancer stratification and localization are performed simultaneously. Many cancer types are characterized by altered receptor expression, such as somatostatin receptors, folate receptors or Her2 (human epidermal growth factor receptor 2). Similar correlations are also known for a multitude of transporters, such as glucose transporters, amino acid transporters or hNIS (human sodium iodide symporter), as well as cell specific proteins, such as the prostate specific membrane antigen, integrins, and CD20. This review provides a comprehensive description of the methods, targets and agents used in molecular imaging, to outline their application for cancer stratification. Emphasis is placed on radiotracers which are used to identify altered expression patterns of cancer associated markers.

Predictive value of 18F-FDG PET and CT morphologic features for recurrence in pathological stage IA non-small cell lung cancer

Patients with pathological stage IA non-small cell lung cancer (NSCLC) may relapse despite complete surgical resection without lymphovascular invasion. A method of selecting a high-risk group for adjuvant therapy is necessary. The aim of this study was to assess the predictive value of F-fluorodeoxyglucose (FDG) uptake and the morphologic features of computed tomography (CT) for recurrence in pathological stage IA NSCLC.One hundred forty-five patients with pathological stage IA NSCLC who underwent pretreatment with FDG positron emission tomography and CT evaluations were retrospectively enrolled. The associations among tumor recurrence and patient characteristics, maximal standard uptake value (SUVmax) of primary tumors, and CT imaging features were investigated using univariate and multivariate analyses. A receiver operating characteristic (ROC) curve analysis was performed to quantify the predictive value of these factors.Tumor recurrence developed in 21 (14.5%) of the 145 patients, and the 5-year recurrence-free survival rate was 77%. The univariate analysis demonstrated that SUVmax, the grade of histological differentiation, tumor size, and the presence of bronchovascular bundle thickening were significant predictive factors (P < 0.05). A higher SUVmax (≥2.5) (P = 0.021), a lower ground-glass opacity ratio (≤17%) (P = 0.014), and the presence of bronchovascular bundle thickening (P = 0.003) were independent predictive factors of tumor recurrence in the multivariate analysis. The use of this predictive model yielded a greater area under the ROC curve (0.877), which suggests good discrimination.The combined evaluation of FDG uptake and CT morphologic features may be helpful in the prediction of recurrence in patients with pathological stage IA NSCLC and in the stratification of a high-risk group for postoperative adjuvant therapy or prospective clinical trials.

Prognostic value of total lesion glycolysis by 18F-FDG PET/CT in surgically resected stage IA non-small cell lung cancer

Despite the favorable prognosis of stage IA non-small cell lung cancer (NSCLC), the disease recurs after complete surgical resection in 20%-30% of patients. This study determined the prognostic value of various metabolic parameters of (18)F-FDG PET/CT in surgically resected stage IA NSCLC.

METHODS

We retrospectively reviewed 248 patients with stage IA NSCLC who underwent lobectomy and complete lymph node dissection after PET/CT. A region of interest was drawn on the primary lesion, and metabolic indices such as metabolic tumor volume, maximum standardized uptake value (SUV(max)), and total lesion glycolysis (TLG) were measured using an SUV cutoff of 2.5.

RESULTS

The patients included 134 men and 114 women, and the mean age was 63.03 ± 10.01 y; 129 were stage T1a (≤ 2 cm) and 119 were T1b (>2 cm). The median follow-up period was 36.6 mo. Recurrence took place in 15 patients. The mean (± SD) SUV(max), metabolic tumor volume, and TLG were 4.55 ± 3.75, 5.92 ± 5.57, and 14.42 ± 17.35, respectively. The cutoffs of SUV(max) and TLG were 3.7 and 13.76, respectively. The 5-y overall survival (OS) was 95.1% in low-SUV(max) patients and 82.2% in high-SUV(max) patients (P = 0.02). The 5-y OS was 93.7% in low-TLG patients and 78.3% in high-TLG patients (P = 0.01). On multivariate analysis, TLG was a risk factor for OS (hazard ratio, 3.159; P = 0.040), but SUV(max) showed marginal significance (P = 0.064). The concordance index of the TLG model was 0.676 (95% CI, 0.541-0.812).

CONCLUSION

TLG was a significant prognostic factor for OS in patients with stage IA NSCLC.