Prognostic value of 18F-FDG PET-CT metabolic index for nasopharyngeal carcinoma

Predictive value of metabolic parameters and apparent diffusion coefficient derived from 18F-FDG PET/MR in patients with non-small cell lung cancer

BACKGROUND

Multiple models intravoxel incoherent motion (IVIM) based 18F-fluorodeoxyglucose positron emission tomography-magnetic resonance(18F-FDG PET/MR) could reflect the microscopic information of the tumor from multiple perspectives. However, its value in the prognostic assessment of non-small cell lung cancer (NSCLC) still needs to be further explored.

OBJECTIVE

To compare the value of 18F-FDG PET/MR metabolic parameters and diffusion parameters in the prognostic assessment of patients with NSCLC.

METERIAL AND METHODS

Chest PET and IVIM scans were performed on 61 NSCLC patients using PET/MR. The maximum standard uptake value (SUVmax), metabolic tumor volume (MTV), total lesion glycolysis (TLG), diffusion coefficient (D), perfusion fraction (f), pseudo diffusion coefficient (D*) and apparent diffusion coefficient (ADC) were calculated. The impact of SUVmax, MTV, TLG, D, f, D*and ADC on survival was measured in terms of the hazard ratio (HR) effect size. Overall survival time (OS) and progression-free survival time (PFS) were evaluated with the Kaplan-Meier and Cox proportional hazard models. Log-rank test was used to analyze the differences in parameters between groups.

RESULTS

61 NSCLC patients had an overall median OS of 18 months (14.75, 22.85) and a median PFS of 17 months (12.00, 21.75). Univariate analysis showed that pathological subtype, TNM stage, surgery, SUVmax, MTV, TLG, D, D* and ADC were both influential factors for OS and PFS in NSCLC patients. Multifactorial analysis showed that MTV, D* and ADC were independent predicting factors for OS and PFS in NSCLC patients.

CONCLUSION

MTV, D* and ADC are independent predicting factors affecting OS and PFS in NSCLC patients. 18F-FDG PET/MR-derived metabolic parameters and diffusion parameters have clinical value for prognostic assessment of NSCLC patients.

The prognostic value of pretreatment 18F-FDG PET-CT parameters with peripheral blood markers in patients with de novo metastatic nasopharyngeal carcinoma

BACKGROUND AND PURPOSE

To develop and validate a prognostic nomogram based on pretreatment 18F-fluorodeoxyglucose positron emission tomography/computed tomography (PET-CT)radiomics parameters and peripheral blood markers for risk stratification in patients with de novo metastatic nasopharyngeal carcinoma (dmNPC).

MATERIALS AND METHODS

A total of 558 patients with dmNPC were retrospectively enrolled between 2011 and 2019. Eligible patients were randomly divided into training and validation cohorts (7:3 ratio). A Cox regression model was used to identify prognostic factors for overall survival (OS). The predictive accuracy and discriminative ability of the prognostic nomogram were determined using the concordance index (C-index) and calibration curve.

RESULTS

Independent factors derived from multivariable analysis of the training cohort to predict death were lactate dehydrogenase levels, pretreatment Epstein-Barr virus DNA, total lesion glycolysis of locoregional lesions, number of metastatic lesions, and age, all of which were assembled into a nomogram with (nomogram B) or without PET-CT parameters (nomogram A). The C-index of nomogram B for predicting death was 0.70, which was significantly higher than the C-index values for nomogram A. Patients were then stratified into low- and high-risk groups based on the scores calculated using nomogram B for OS. The median OS was significantly higher in the low-risk group than in the high-risk group (69.60 months [95 % CI: 58.50-108.66] vs. 21.40 months [95 % CI: 19.20-23.90]; p＜0.01). All the results were confirmed in the validation cohort.

CONCLUSION

The proposed nomogram including PET-CT parameters yielded accurate prognostic predictions for patients with dmNPC, enabling effective risk stratification for these patients.

PET/CT standardized uptake value and EGFR expression predicts treatment failure in nasopharyngeal carcinoma

OBJECTIVE

This study inventively combines epidermal growth factor receptor (EGFR) expression of the primary lesion and standardized uptake value (SUV) of positron emission tomography and computed tomography (PET/CT) to predict the prognosis of nasopharyngeal carcinoma (NPC). This study aimed to evaluate the predictive efficacy of maximum standard uptake value (SUVmax) and EGFR for treatment failure in patients with NPC.

METHODS

This retrospective study reviewed the results of EGFR expression and pretreatment ¹⁸F-FDG PET/CT of 313 patients with NPC. Time-dependent receiver operator characteristics was used for analyzing results and selecting the optimal cutoff values. Cox regression was used to screen out multiple risk factors. Cumulative survival rate was calculated by Kaplan-Meier.

RESULTS

The selected cutoff value of SUVmax-T was 8.5. The patients were categorized into four groups according to EGFR expression and SUVmax-T. There were significant differences in the 3-year local recurrence-free survival (LRFS) (p = 0.0083), locoregional relapse-free survival (LRRFS) (p = 0.0077), distant metastasis-free survival (DMFS) (p = 0.013), and progression-free survival (PFS) (p = 0.0018) among the four groups. Patients in the EGFR-positive and SUVmax-T > 8.5 group had the worst survival, while patients in the EGFR-negative and SUVmax-T ≤ 8.5 group had the best prognosis. Subsequently, patients with only positive EGFR expression or high SUVmax-T were classified as the middle-risk group. There were also a significant difference in 3-year overall survival among the three risk groups (p = 0.034). SUVmax-T was associated with regional recurrence-free survival and LRRFS in multivariate analysis, whereas EGFR was an independent prognostic factor for LRRFS, DMFS, and PFS.

CONCLUSION

The combination of SUVmax-T and EGFR expression can refine prognosis and indicate clinical therapy.

Focal Nasopharyngeal Activity Detected on [18F]FDG PET/CT: Clinical Implications and Comparison of Metabolic Parameters for Prediction of Malignancy

Purpose

We aimed to investigate the incidence and clinical significance of incidental focal nasopharyngeal uptake on [18F]FDG PET/CT and to evaluate the diagnostic performance of various metabolic parameters to differentiate between benign and malignant nasopharyngeal lesions.

Methods

A total of 63 consecutive patients with incidental focal nasopharyngeal uptake on [18F]FDG PET/CT and subsequent nasopharyngeal biopsy were retrospectively enrolled. In addition, baseline pretherapeutic [18F]FDG PET/CT images of 59 patients with newly diagnosed pathologically proven nasopharyngeal carcinoma (NPC) were reviewed. Maximum standardized uptake value (SUVmax), mean SUV (SUVmean), nasopharynx-to-palatine tonsil ratio (NPR), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of the nasopharyngeal lesions were determined. Receiver operating characteristic (ROC) curve analysis was used to evaluate the diagnostic performance of the metabolic parameters.

Results

Incidental focal nasopharyngeal uptake in two patients (3.2%, 2/63) was pathologically confirmed to be NPC. All the metabolic parameters (SUVmax, SUVmean, NPR, MTV, and TLG) demonstrated significantly greater values in patients with NPC compared with patients with benign or physiological nasopharyngeal uptake (p < 0.001). Among the metabolic parameters, NPR demonstrated the greatest area under the curve of 0.992 (p < 0.05), with a sensitivity of 96.7% and a specificity of 93.4% when a cut-off of 1.1 was used. Similar results were seen in nasopharyngeal lesions without morphological abnormality.

Conclusion

NPC is an infrequent but important cause of incidental focal nasopharyngeal uptake on [18F]FDG PET/CT. Metabolic parameters were shown to be useful to differentiate between benign and malignant nasopharyngeal lesions, and NPR showed the best diagnostic performance.

M1 stage subdivisions based on 18F-FDG PET-CT parameters to identify locoregional radiotherapy for metastatic nasopharyngeal carcinoma

Purpose

To establish a risk classification of de novo metastatic nasopharyngeal carcinoma (mNPC) patients based on ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET-CT) radiomics parameters to identify suitable candidates for locoregional radiotherapy (LRRT).

Methods

In all, 586 de novo mNPC patients who underwent ¹⁸F-FDG PET-CT prior to palliative chemotherapy (PCT) were involved. A Cox regression model was performed to identify prognostic factors for overall survival (OS). Candidate PET-CT parameters were incorporated into the PET-CT parameter score (PPS). Recursive partitioning analysis (RPA) was applied to construct a risk stratification system.

Results

Multivariate Cox regression analyses revealed that total lesion glycolysis of locoregional lesions (LRL-TLG), the number of bone metastases (BMs), metabolic tumor volume of distant soft tissue metastases (DSTM-MTV), pretreatment Epstein-Barr virus DNA (EBV DNA), and liver involvement were independent prognosticators for OS. The number of BMs, LRL-TLG, and DSTM-MTV were incorporated as the PPS. Eligible patients were divided into three stages by the RPA-risk stratification model: M1a (low risk, PPS_low + no liver involvement), M1b (intermediate risk, PPS_low + liver involvement, PPS_high + low EBV DNA), and M1c (high risk, PPS_high + high EBV DNA). PCT followed by LRRT displayed favorable OS rates compared to PCT alone in M1a patients (p < 0.001). No significant survival difference was observed between PCT plus LRRT and PCT alone in M1b and M1c patients (p > 0.05).

Conclusions

The PPS-based RPA stratification model could identify suitable candidates for LRRT. Patients with stage M1a disease could benefit from LRRT.

Pretreatment [18F]FDG PET/CT and MRI in the prognosis of nasopharyngeal carcinoma

OBJECTIVE

The present study aimed to assess the prognostic interest of metabolic and anatomic parameters derived from 2-deoxy-2-[¹⁸F]fluoro-D-glucose positron emission tomography/computed tomography ([¹⁸F]FDG PET/CT) and head and neck magnetic resonance imaging (HN-MRI) for better management of nasopharyngeal carcinoma (NPC).

METHODS

In this study, pre-treatment [¹⁸F]FDG PET/CT and HN-MRI parameters of NPC patients diagnosed between January 2017 and December 2018, were prospectively investigated. Correlation between those parameters and 4-year patient's survival outcomes was evaluated using Kaplan-Meier and Cox-regression analyses.

RESULTS

Our results revealed a significant association between pre-treatment nodal-maximum standardized uptake value (N-SUV max) and N categories (p = 0.01), between pre-treatment node-to-tumor SUV ratio (NTR) and both tumor size (p = 0.01) and N categories (p = 0.009), as well as between metabolic tumor volume (MTV) and both tumor size and NPC overall stage (p < 0.000). In multivariate analyses, pre-treatment N-SUV max, NTR and MTV were significant independent predictors of overall survival, distant metastasis-free survival, and progression-free survival (PFS) (p < 0.05). N-SUV max and MTV were also found to be significant independent predictors of loco-regional recurrence-free survival (p < 0.05), whereas HN-MRI detection of skull-base bone invasion was an independent factor associated with worse PFS in NPC (p = 0.03).

CONCLUSIONS

The present study highlights N-SUV max, NTR and MTV derived from [¹⁸F]FDG PET/CT, and skull-base bone invasion defined by HN-MRI, as promising metabolic and anatomic prognosis biomarkers for NPC.

Combing MRI Perfusion and 18F-FDG PET/CT Metabolic Biomarkers Helps Predict Survival in Advanced Nasopharyngeal Carcinoma: A Prospective Multimodal Imaging Study

We prospectively investigated the prognostic value of imaging parameters for nasopharyngeal carcinoma (NPC) using dynamic contrast-enhanced MRI (DCE-MRI), diffusion-weighted imaging (DWI), and 2-deoxy-2-[fluorine-18]fluoro-D-glucose positron emission tomography (¹⁸F-FDG PET)/computed tomography (CT). Patients with stage III-IVb NPC underwent F-FDG PET/CT, DCE-MRI, and DWI before treatment. Kaplan-Meier and Cox-regression analyses were used to assess associations of PET and MRI imaging biomarkers with overall survival (OS) and recurrence-free survival (RFS). We used independent prognosticators to establish prognostic models; model performance was examined using Harrell's concordance index (c-index). Sixty-one patients were available for analysis, as 13 patients died and 20 experienced recurrence. Total lesion glycolysis (TLG) (p = 0.002) from PET/CT and the initial area under the curve (iAUC) (p = 0.036) from DCE-MRI were identified as independent prognosticators of OS; Epstein-Barr virus (EBV) DNA (p = 0.027), the extracellular volume fraction (V_e) (p = 0.027) from DCE-MRI, and TLG/iAUC (p = 0.025) were significant predictors of RFS. The c-indices of the prognostic models incorporating TLG + iAUC in predicting OS and incorporating EBV DNA + V_e + TLG/iAUC in predicting RFS were 0.79 and 0.76, respectively. These were significantly higher than the corresponding c-indices of the TNM staging system (p = 0.047 and 0.025, respectively); they were also higher than those of models with only MRI or PET biomarkers. In conclusion, the combination of pretreatment DCE-MRI and ¹⁸F-FDG PET/CT imaging biomarkers helps survival prediction in advanced NPC. Integrating MRI perfusion with PET metabolism and plasma EBV information may aid clinicians in planning the optimal personalized management strategy.

Integrated PET-CT treatment planning of locally advanced head and neck cancer: a review of imaging features and the contribution to clinical outcomes

Aim:

Little is known about how integrated positron emission tomography-computed tomography (IPET-CT), both imaging tools and not methods of treatment, contributes to head and neck cancer patients’ outcomes. We analysed the clinical PET-CT findings and their correlation to the effects of applied contemporary disease management.

Methodology:

A retrospective analysis of 29 individuals who underwent treatment planning fusion of PET-CT for radiochemotherapy of locally advanced head and neck cancer between 2010 and 2016 was undertaken. Gross tumour volumes were categorised as small (≤36 cm3) or large (>36 cm3), and tumour responses to therapy were classified as complete or incomplete.

Results:

The overall rates of complete tumour response (CTR), 3-year crude survival and failure (all types included) were 80%, 41% and 55%, respectively. Comparative analysis of tumour volume subsets revealed no significant differences in the rates of CTR (p > 0.80), 3-year survival (p > 0.30) and locoregional recurrence (p > 0.70). CTR was associated with improved prognosis (p > 0.05) and fewer tumour relapses (p < 0.02).

Conclusion:

Our findings, although not truly conclusive, appear in line with those in the literature. Smaller tumour volumes and CTRs shown on integrated PET-CT are likely to play important roles in the promotion of better prognosis, but further study with larger patient numbers and more data are needed.

Multiparametric positron emission tomography/magnetic resonance imaging in nasopharyngeal carcinoma: Correlations between magnetic resonance imaging functional parameters and 18F-fluorodeoxyglucose positron emission tomography imaging biomarkers and their predictive value for treatment failure

Objectives:

The clinical significance of positron emission tomography/magnetic resonance imaging (PET/MRI) functional parameters in nasopharyngealcarcinoma (NPC) remains unclear. The purpose of this prospective study was two-fold: (1) to investigate the associations between simultaneously acquired PET/MRI perfusion, diffusion, and glucose metabolism parameters in patients with NPC and (2) to analyze their predictive value with respect to treatment failure.

Materials and Methods:

We enrolled 85 patients with primary NPC who simultaneously underwent¹⁸F-fluorodeoxyglucose PET/CT and PET/MRI before definitive treatment. The following variables were determined: (1) functional parameters from the MRI component, including perfusion values (K^trans,k_ep,v_e, and initial area under the enhancement curve) and apparent diffusion coefficient (ADC) values, and (2) PET parameters, including metabolic tumor volume (MTV). The reciprocal interrelationships between these parameters and their correlations with treatment failure were examined.

Results:

We observed significant negative associations between K^trans and ADC (r = −0.215, P = 0.049) as well as between v_e and ADC (r = −0.22, P = 0.04). Correlations between PET and MRI functional parameters were not statistically significant. Treatment failures were observed in 21.2% of patients without distant metastases. Multivariate analysis identified v_e as a significant independent predictor for treatment failure (P = 0.022), whereas MTV showed a borderline significance (P = 0.095). Patients in whom both v_e and MTV values were increased had a significantly higher rate of treatment failure (62.5%) than those with either one (21.9%) or no (7.7%) increased parameter (P = 0.004).

Conclusion:

Correlation analyses revealed complex interrelationships among PET and MRI indices measured in patients with NPC. These parameters may have a complementary role in predicting treatment failure in this clinical setting.

Prognostic value of [18F]FDG PET/CT parameters in surgically resected primary lung adenocarcinoma: a single-center experience

OBJECTIVE

To evaluate the prognostic role of maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) measured by FDG-positron emission tomography (PET)/computed tomography (CT) in patients with primary lung adenocarcinoma undergoing surgical resection.

METHODS

All consecutive patients undergoing curative surgery for primary lung adenocarcinoma at the Thoracic Surgery Unit of the University Hospital of Parma between January 2009 and December 2014 were retrospectively analyzed. The cutoff point of each continuous PET parameter was determined through receiver operating characteristic curve and Youden index, using overall survival (OS) as the classification status. Univariate and multivariate Cox proportional hazards models were applied to evaluate the association between OS and potential prognostic variables, including SUVmax, MTV, and TLG.

RESULTS

A total of 193 patients were considered eligible for this study. The mean 5-year OS rate was 70.5 ± 3.5%. Acinar and lepidic patterns were more frequently associated with absent or low (<2.5) SUVmax values [18F]FDG uptake. At univariate analysis, male sex, advanced stage, micropapillary and solid pattern, lymphatic, blood vessels and pleural invasion, high SUVmax, MTV, and TLG were significantly associated with poorer OS. Multivariate analyses revealed that only sex, stage, and TLG were independent factors for OS, with male sex, stage 3+4, and high TLG value (p = 0.041) significantly associated with poorer OS.

CONCLUSIONS

In this study, [18F]FDG PET/CT parameters SUVmax, MTV, and TLG were prognostic factors in patients with surgically resected lung adenocarcinoma, able to predict OS and helping to further stratify these patients into prognostic subsets. Elevated TLG was also an independent predictor for shorter OS.

Correlation of PET-CT, MRI and histopathology findings in the follow-up of patients with nasopharyngeal cancer

Introduction

Surgical treatment options are limited for nasopharyngeal cancer for many reasons including epidemiological and histological properties, proximity to important structures, heavy lymphatic drainage, and the difficulty in ensuring a safe surgical margin; therefore primary treatment is generally radiotherapy and chemotherapy. With current radiotherapy technology, oncological success has been increased and the quality of life of patients during the post- radiotherapy period is improved.

Objective

The role of magnetic resonance imaging and positron emission-computed tomography in the follow-up of recurrent nasopharyngeal cancer patients who were initially treated with radiotherapy was evaluated with respect to histopathological findings.

Methods

A total of 110 patients with nasopharyngeal cancer who had received radiotherapy were included in the study. Patients who were suspected to have recurrence according to endoscopic nasopharyngeal examination and magnetic resonance imaging findings were requested to undergo positron emission-computed tomography. Biopsies were taken from 40 patients who had suspicious lesions in positron emission-computed tomography images. These patients’ age, gender, presence/absence of contrast enhancement on magnetic resonance imaging, the SuvMax values of nasopharyngeal and neck lesions, T/N phases at initial diagnosis, histopathological recurrence, and history of neck dissection were assessed.

Results

Recurrence was observed in 8 patients (20.0%). Among these, 4 (10.0%) had recurrence at the nasopharynx and 4 (10.0%) at the neck. Patients with recurrence were found to be of older age, male gender, advanced T/N phase, contrast enhancement on magnetic resonance imaging, and higher nasopharyngeal and neck SuvMax values in positron emission-computed tomography. However, these differences were not statistically significant. Only the history of neck dissection was significantly more common among those with recurrence (p < 0.001). However, in multivariate analysis, those with a nasopharyngeal SuvMax value higher than 4.58 were found to have 7.667-fold higher risk for recurrence (p = 0.036).

Conclusions

Magnetic resonance imaging and positron emission-computed tomography should be evaluated together in the follow-up of nasopharyngeal cancer. Patients with minimal SuvMax 4.58 on positron emission-computed tomography after contrast enhancement in the T2 sequence on magnetic resonance imaging may considered appropriate for biopsy. Biopsies in patients with a SuvMax value lower than 4.58 can be avoided. Thus, patients avoid surgical stress and unnecessary costs.

Quantitative volumetric metabolic measurement of solitary pulmonary nodules by F-18 fluorodeoxyglucose positron emission tomography-computed tomography

Background

This study aims to evaluate the effect of quantitative volumetric metabolic measurements in F-18 fluorodeoxyglucose positron emission tomographycomputed tomography to distinguish benign and malignant solitary pulmonary nodules.

Methods

We retrospectively reviewed 78 patients (56 males; 22 females; mean age 61±11.9 years; range, 32 to 82 years) with solitary pulmonary nodules who underwent F-18 fluorodeoxyglucose positron emission tomography-computed tomography. Patients were classified as benign, malignant and metastatic lesions according to pathology results. Metabolic volume, maximum standardized uptake value, mean standardized uptake value, maximum metabolic index and mean metabolic index were measured. Mean, median and standard error values were calculated for each group. Nonparametric tests were used for the comparison of each group. Partial correlation analysis was used for the relationship between parameters. For all parameters, cut-off values were obtained with receiver operating characteristic analysis.

Results

Of 78 lesions, 10 were benign (12.8%), 38 were primary lung carcinoma (48.7%) and 30 were metastatic lung nodules (38.5%). There was a significant difference between benign lesions and primary lung cancer and between primary lung cancer and metastatic groups in all parameters (p<0.05). We determined highly significant positive correlation between maximum standardized uptake value and maximum metabolic index (r=0.73; p<0.05), and moderate positive correlation between mean standardized uptake value and mean metabolic index (r=0.56; p<0.05). In receiver operating characteristic analysis, maximum standardized uptake value and mean standardized uptake value were found to be the most sensitive and specific methods for benign/malignant discrimination. In the cut-off value=2.59, the sensitivity and specificity for maximum standardized uptake value were 98.0% and 91.7%, respectively. In the cut-off value=1.65, the sensitivity and specificity for mean standardized uptake value were 94.0% and 91.7%, respectively.

Conclusion

Maximum metabolic index value is highly correlated with maximum standardized uptake value in benign/malignant solitary pulmonary nodules discrimination by F-18 fluorodeoxyglucose positron emission tomographycomputed tomography. Maximum metabolic index can also be used for discrimination of primary/metastatic malignant lesions.

Textural features on 18F-FDG PET/CT and dynamic contrast-enhanced MR imaging for predicting treatment response and survival of patients with hypopharyngeal carcinoma

The utility of multimodality molecular imaging for predicting treatment response and survival of patients with hypopharyngeal carcinoma remains unclear. Here, we sought to investigate whether the combination of different molecular imaging parameters may improve outcome prediction in this patient group.Patients with pathologically proven hypopharyngeal carcinoma scheduled to undergo chemoradiotherapy (CRT) were deemed eligible. Besides clinical data, parameters obtained from pretreatment 2-deoxy-2-[fluorine-18]fluoro-D-glucose positron emission tomography/computed tomography (F-FDG PET/CT), dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI), and diffusion-weighted MRI were analyzed in relation to treatment response, recurrence-free survival (RFS), and overall survival (OS).A total of 61 patients with advanced-stage disease were examined. After CRT, 36% of the patients did not achieve a complete response. Total lesion glycolysis (TLG) and texture feature entropy were found to predict treatment response. The transfer constant (K), TLG, and entropy were associated with RFS, whereas K, blood plasma volume (Vp), standardized uptake value (SUV), and entropy were predictors of OS. Different scoring systems based on the sum of PET- or MRI-derived prognosticators enabled patient stratification into distinct prognostic groups (P <.0001). The complete response rate of patients with a score of 2 was significantly lower than those of patients with a score 1 or 0 (14.7% vs 58.9% vs 75.7%, respectively, P = .007, respectively). The combination of PET- and DCE-MRI-derived independent risk factors allowed a better survival stratification than the TNM staging system (P <.0001 vs .691, respectively).Texture features on F-FDG PET/CT and DCE-MRI are clinically useful to predict treatment response and survival in patients with hypopharyngeal carcinoma. Their combined use in prognostic scoring systems may help these patients benefit from tailored treatment and obtain better oncological results.

Prognostic Value of Volume-Based Positron Emission Tomography/Computed Tomography in Nasopharyngeal Carcinoma Patients after Comprehensive Therapy

Objective

We assessed the prognostic value of standardized uptake value (SUV) and volume-based methods including whole-body metabolic tumor volume (WBMTV) and whole-body total lesion glycolysis (WBTLG) using ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) of patients with nasopharyngeal carcinoma (NPC) after therapy.

Methods

A total of 221 posttherapy NPC cases were enrolled, all of whom had undergone PET/CT scanning and follow-up in this retrospective study. The diagnostic results of PET/CT were analyzed and compared with histopathological diagnosis or clinical follow-up. Receiver operator characteristic curves, the Kaplan-Meier method, and the log-rank test were used to assess the optimal cutoff values for WBMTV and WBTLG to identify independent predictors of survival.

Results

The detection rates of the threshold SUV were 2.5, 20%, and 40%, and SUV background methods were 65.6% (378/576), 80.2% (462/576), 71.5% (412/576), and 90.4% (521/576), respectively (P < 0.005). Patients with a WBMTV < 8.10 and/or a WBTLG < 35.58 had significantly better 5-year overall survival than those above the cutoffs (90.7% versus 51.2%, P < 0.001; 91.7% versus 50.4%, P < 0.001), respectively. Multivariate Cox regression modeling showed both WBTLG (RR, 1.002; P = 0.004) and age (RR, 1.046; P = 0.006) could be used to predict overall survival. WBTLG (RR, 1.003; P < 0.001) may have predictive relevance in estimating disease-free survival.

Conclusions

SUV volume-based threshold background methodology had a significantly higher detection rate for metastatic lesions. WBTLG could be used as an independent prognostic indicator for posttherapy NPC.

Significant value of 18F-FDG-PET/CT in diagnosing small cervical lymph node metastases in patients with nasopharyngeal carcinoma treated with intensity-modulated radiotherapy

BACKGROUND

Little is known about the nature of metastasis to small cervical lymph nodes (SCLNs) in the patients with nasopharyngeal carcinoma (NPC) examined by using 18-fluoro-2-deoxy-glucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT). The present study aimed to evaluate the diagnostic values of PET/CT in identifying metastasis in SCLNs in NPC patients.

METHODS

Magnetic resonance images (MRI) and PET/CT scans for 470 patients with newly diagnosed, non-distant metastatic NPC were analyzed. Metastatic rates of SCLNs were defined by the positive number of SCLNs on PET/CT scans and total number of SCLNs on MRI scans. Receiver operating characteristic curve was applied to compare PET/CT-determined stage with MRI-determined stage.

RESULTS

In total, 2082 SCLNs were identified, with 808 (38.8%) ≥ 5 and < 6 mm in diameter (group A), 526 (25.3%) ≥ 6 and < 7 mm in diameter (group B), 374 (18.0%) ≥ 7 and < 8 mm in diameter (group C), 237 (11.4%) ≥ 8 and < 9 mm in diameter (group D), and 137 (6.5%) ≥ 9 and < 10 mm in diameter (group E). The overall metastatic rates examined by using PET/CT for groups A, B, C, D, and E were 3.5%, 8.0%, 31.3%, 60.0%, and 83.9%, respectively (P < 0.001). In level IV/Vb, the metastatic rate for nodes ≥ 8 mm was 84.6%. PET/CT examination resulted in modification of N category and overall stage for 135 (28.7%) and 46 (9.8%) patients, respectively. The areas under curve of MRI-determined and PET/CT-determined overall stage were 0.659 and 0.704 for predicting overall survival, 0.661 and 0.711 for predicting distant metastasis-free survival, and 0.636 and 0.663 for predicting disease-free survival.

CONCLUSIONS

PET/CT was more effective than MRI in identifying metastatic SCLNs, and the radiologic diagnostic criteria for metastatic lymph nodes in level IV/Vb should be re-defined.

Prognostic value of maximum standard uptake value, metabolic tumor volume, and total lesion glycolysis of positron emission tomography/computed tomography in patients with nasopharyngeal carcinoma: A systematic review and meta-analysis

BACKGROUND

The maximal standard uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of positron emission tomography/computed tomography (PET/CT) in patients with nasopharyngeal carcinoma (NPC) perform as new prognostic factors, but the outcomes of the published articles were inconclusive. In this meta-analysis, we evaluated the prognostic value of SUVmax, MTV, and TLG of PET/CT in patients with NPC.

METHODS

Relevant English articles were searched in PubMed and EMBASE. The data of patients and the survival outcomes were extracted. Pooled hazard ratios (HRs) were accounted to assess the prognostic value of the SUVmax, MTV, and TLG.

RESULTS

This meta-analysis combined 10 primary studies including 941 patients with NPC. The combined HRs (95% confidence interval [CI] of higher SUVmax, higher MTV, and higher TLG for event-free survival were 2.33 (95% CI, 1.39-3.91, P = .001), 2.51 (95% CI, 1.61-3.91, P < .0001), and 2.74 (95% CI, 1.91-3.93, P < .00001), respectively. Regarding overall survival, the combined HRs were 2.50 (95%CI, 1.65-3.78, P < .0001) with higher SUVmax, 3.30 (95% CI, 1.92-5.69, P < .0001) with higher MTV and 3.18 (95% CI, 1.70-5.96, P = .0003) with higher TLG.

CONCLUSION

SUVmax, MTV, and TLG were significant prognostic predictors in patients with NPC. And the results suggested that higher SUVmax, MTV, and TLG were associated with worse prognosis.

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

BACKGROUND

The prognostic role of 18F-fluorodeoxyglucose positron emission tomography CT (18F-FDG PET/CT) parameters is still controversial in nasopharyngeal carcinoma patients. We sought to perform a systematic review and meta-analysis to explore the prognostic value of maximal standardized uptake value (SUVmax), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) on event-free survival (EFS) and overall survival (OS) in nasopharyngeal carcinoma patients.

RESULTS

Fifteen studies comprising 1,938 patients were included in this study. The combined hazard ratios (HRs) for EFS were 2.63 (95%CI 1.71-4.05) for SUVmax, 2.55 (95%CI 1.49-4.35) for MTV, and 3.32 (95%CI 1.23-8.95) for TLG. The pooled HRs for OS were 2.07 (95%CI 1.54-2.79) for SUVmax, 3.86 (95%CI 1.85-8.06) for MTV, and 2.60 (95%CI 1.55-4.34) for TLG. The prognostic role of SUVmax, MTV and TLG remained similar in the sub-group analyses.

METHODS

A systematic literature search was performed to identify studies which associated 18F-FDG PET/CT to clinical survival outcomes of nasopharyngeal carcinoma patients. The summarized HRs for EFS and OS were estimated by using fixed- or random-effect models according to heterogeneity between trials.

CONCLUSIONS

The present meta-analysis confirms that high values of SUVmax, MTV and TLG predicted a higher risk of adverse events or death in patients with nasopharyngeal carcinoma, despite clinically heterogeneous nasopharyngeal carcinoma patients and the various methods adopted between these studies.

Prognostic value of pretreatment 18F-FDG PET-CT for nasopharyngeal carcinoma patients

BACKGROUND

Nasopharyngeal carcinoma (NPC) is a special subtype of head and neck cancer (HNC). At present, there are no highly specific prognostic markers to aid in tumor grading and guide patient treatment modalities for NPC. The prognostic value of pretreatment F-fluorodeoxyglucose positron emission tomography-computed tomography (F-PET-CT) in NPC patients is controversial and no consensus exists as to its predictive capability.

METHODS

To analyze the predictive efficacy of F-PET-CT imaging in NPC patients, data from MEDLINE, EMBASE, the Cochrane library, CBM, CNKI, and VIP (inception to July 2016) were accessed. Results from prospective and retrospective observational studies that used F-FDG PET to predict disease prognosis in NPC patients were used for analysis. Two authors independently assessed study quality and extracted data. Event-free survival (EFS) was considered the primary endpoint and overall survival rate (OS) was considered the secondary endpoint.

RESULTS

Data from 14 studies and 1134 patients were included in our analysis. The hazard ratios (HRs) of maximum standardized uptake value of primary tumor (SUVmax-T), metabolic tumor volume of primary tumor (MTV-T), and total lesional glycolysis of primary tumor (TLG-T) for EFS were 1.31 (95% confidence interval [CI], 1.11-1.55, P = .001), 2.38 (95% CI 1.53-3.70, P < .001), and 1.65 (95% CI 0.76-3.59, P = .21), respectively. Among studies including TLG-T, those with a fixed SUV of 2.5 had an HR of 3.55 (95% CI, 1.42-8.84, P = .007). The HRs of SUVmax-T and MTV-T for OS were 2.19 (95% CI, 1.47-3.27, P < .001) and 2.69 (95% CI, 1.01-7.17, P = .05), respectively. Among studies including MTV-T, those with a fixed SUV of 2.5 had an HR of 4.07 (95% CI, 2.22-7.46, P < .001). Tests used for assessing predictive value of pretreatment SUVmax, MTV, and TLG of lymph nodes for EFS and OS showed that these parameters did not have significant predictive value (P>.05).

CONCLUSION

Our results suggested that SUVmax, MTV, and TLG (with a fixed SUV of 2.5) of primary tumors before treatment initiation may be independent prognostic factors for NPC patients; however, SUVmax, MTV, and TLG of metastatic lymph nodes are not.

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.

Lymph node standardized uptake values at pre-treatment 18F-fluorodeoxyglucose positron emission tomography as a valuable prognostic factor for distant metastasis in nasopharyngeal carcinoma

Objective:

The aim of the present study was to evaluate prognostic values of pre-treatment fluorine-18 fludeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) parameters for predicting the distant metastasis (DM) of nasopharyngeal cancer.

Methods:

73 patients diagnosed with nasopharyngeal cancer with regional lymph node (LN) involvement, who underwent pre-treatment ¹⁸F-FDG PET evaluation between January 2005 and December 2012, were retrospectively reviewed. We assessed the ¹⁸F-FDG PET parameters of the primary tumours (T–) and regional LNs (N–). For patients with bilateral retropharyngeal, bilateral neck and/or supraclavicular LN involvement, we also assessed the ¹⁸F-FDG PET parameters of the farthest LN station [N(f)–]. The following ¹⁸F-FDG PET parameters were evaluated: maximum standardized uptake value (SUV_max), mean standardized uptake value (SUV_mean), peak standardized uptake value (SUV_peak), metabolic tumour volumes (MTVs) (MTV₃₀–MTV₇₀, which were calculated as the tumour volume with 30%, 40%, 50%, 60% and 70% of the SUV_max as the threshold, respectively) and total lesion glycolysis (TLG) (TLG₃₀–TLG₇₀, which were determined by the product of each MTV and the corresponding SUV_mean within that MTV). Distant metastasis-free survival (DMFS) rates were estimated from the date of the start of radiotherapy to the date of DM or last follow-up by the Kaplan–Meier method. Univariate and multivariate analyses were performed to identify prognostic factors for DMFS. The median follow-up period was 53 months (range 12–110 months).

Results:

Most patients (95%) received concurrent chemoradiotherapy. The major failure pattern was DM (15 of all patients, 21%) and the 5-year DMFS was 79%. In univariate analysis, the T–SUV_max, T–SUV_mean, T–SUV_peak, N–SUV_max, N–SUV_peak, N(f)–SUV_max and N(f)–SUV_peak were significant prognostic factors for DMFS. In multivariate analysis, the T–SUV_max, T–SUV_peak, N(f)–SUV_max and N(f)–SUV_peak were significant prognostic factors for DMFS. Of these parameters, the N(f)–SUV_max (hazard ratio = 6.524; p = 0.001) and N(f)–SUV_peak (hazard ratio = 5.399; p = 0.001) were the strongest prognostic factors for DMFS.

Conclusion:

In patients with nasopharyngeal cancer with LN involvement, the standardized uptake value parameter of the farthest LN station seems to be an important ¹⁸F-FDG PET parameter for predicting DM. Further studies are needed to validate its clinical significance.

Advances in knowledge:

We found that pre-treatment ¹⁸F-FDG PET parameters of primary tumours and regional LNs (the SUV_max and SUV_peak of the primary tumour and the farthest LN station) were significant prognostic factors for DMFS in patients with nasopharyngeal carcinoma with LN involvement.

The role of PET/CT as a prognosticator and outcome predictor in lung cancer

Positron emission tomography/computed tomography (PET/CT) is an important imaging tool for management of lung cancer and can be utilized in diagnosis, staging, restaging, treatment planning and evaluating treatment response. In the past decade PET/CT has proven to be beneficial for the prediction of prognosis and outcome. PET findings before and after treatment, the quantitative PET parameters such as standardized uptake value (SUV), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) as well as delayed PET/CT imaging can be used to determine patient prognosis and outcome. Other tracers such as hypoxia and proliferation marker tracers may be used for prognostication. The prognostic factors derived from PET/CT imaging help early development of risk-adapted treatment strategies, which provides cost-effective treatment and leads to improved patient management. Here, we discuss findings of studies related to application of PET/CT in lung cancer as well as some technical updates on quantitative PET/CT in lung cancer.

The role of PET/CT in the management of patients affected by head and neck tumors: a review of the literature

The management of head and neck tumor (HNSCC) has been changing over the years, especially due to the aid of imaging techniques that help physicians to attain a correct diagnosis. These techniques represent a valuable tool to help tailor treatment and during follow-up of patients affected by malignancies. The aim of this review is to summarize the results of the most recent and relevant studies about the use of PET imaging in HNSCCs. This review is divided into six chapters: (1) The role of PET/CT in the pre-treatment phase; (2) PET/CT and radiotherapy planning; (3) PET/CT in the post-treatment setting; (4) PET/CT and SUVmax for prediction of prognosis; (5) miscellanea on the utility of PET in specific HNSCCs; (6) non-FDG PET tracers used in HNSCC. Promising results have been obtained so far. Despite the encouraging outcomes, more investigations are needed to warrant the value of this technique, especially in the pre-treatment setting.

Tumor heterogeneity measured on F-18 fluorodeoxyglucose positron emission tomography/computed tomography combined with plasma Epstein-Barr Virus load predicts prognosis in patients with primary nasopharyngeal carcinoma

OBJECTIVES/HYPOTHESIS

Plasma Epstein-Barr virus (EBV) DNA concentrations predict prognosis in patients with nasopharyngeal carcinoma (NPC). Recent evidence also indicates that intratumor heterogeneity on F-18 fluorodeoxyglucose positron emission tomography (¹⁸ F-FDG PET) scans is predictive of treatment outcomes in different solid malignancies. Here, we sought to investigate the prognostic value of heterogeneity parameters in patients with primary NPC.

STUDY DESIGN

Retrospective cohort study.

METHODS

We examined 101 patients with primary NPC who underwent pretreatment ¹⁸ F-FDG PET/computed tomography. Circulating levels of EBV DNA were measured in all participants. The following PET heterogeneity parameters were collected: histogram-based heterogeneity parameters, second-order texture features (uniformity, contrast, entropy, homogeneity, dissimilarity, inverse difference moment), and higher-order (coarseness, contrast, busyness, complexity, strength) texture features.

RESULTS

The median follow-up time was 5.14 years. Total lesion glycolysis (TLG), tumor heterogeneity measured by histogram-based parameter skewness, and the majority of second-order or higher-order texture features were significantly associated with overall survival (OS) and/or recurrence-free survival (RFS). In multivariate analysis, age (P =.005), EBV DNA load (P = .0002), and uniformity (P = .001) independently predicted OS. Only skewness retained the independent prognostic significance for RFS. Tumor stage, standardized uptake value, or TLG did not show an independent association with survival endpoints. The combination of uniformity, EBV DNA load, and age resulted in a more reliable prognostic stratification (P < .001).

CONCLUSIONS

Tumor heterogeneity is superior to traditional PET parameters for predicting outcomes in primary NPC. The combination of uniformity with EBV DNA load can improve prognostic stratification in this clinical entity.

LEVEL OF EVIDENCE

4 Laryngoscope, 127:E22-E28, 2017.

Correlation between histological grade and positron emission tomography parameters in cervical carcinoma

The aim of the present study was to evaluate the changes in cervical cancer glucose metabolism for different levels of cellular differentiation. The metabolic activity was measured by standardized uptake value (SUV), SUV normalized to lean body mass, metabolic tumor volume and total lesion glycolysis using fluorine-18 fluorodeoxyglucose positron emission tomography (PET). A correlation study of these values could be used to facilitate therapeutic choice and to improve clinical practice and outcome. This study considered 32 patients with diagnosed cervical cancers, at different International Federation of Gynecology and Obstetrics stages. Glucose metabolism was assessed by PET examination, and histological specimens were examined to determine their initial grade of differentiation. A correlation study of these values was evaluated. Histological examination showed that all cases were of squamous cell carcinoma. Regarding the differentiation of the tumor, 19 well- to moderately-differentiated tumors and 13 poorly-differentiated tumors were determined. Negative findings for correlations between metabolic parameters and initial grade of histological differentiation were found, and considering that histological grade has been shown to have no consistent prognostic value in cervical cancer treatment, PET imaging could play a significant role in cervical cancer prognosis.

Prognostic utility of (18)F-FDG PET-CT performed prior to and during primary radiotherapy for nasopharyngeal carcinoma: Index node is a useful prognostic imaging biomarker site

PURPOSE

To evaluate the prognostic value of (18)F-FDG-PET-CT performed prior to (prePET) and during the third week (iPET) of radiation therapy (RT) in nasopharyngeal carcinoma (NPC).

MATERIALS AND METHODS

Thirty-patients with newly diagnosed loco-regionally advanced NPC treated with radical RT underwent prePET and iPET. The median follow-up was 26months (8-66.9). The maximum-standardised-uptake-value (SUVmax), metabolic-tumour-volume (MTV) and total-lesional-glycolysis (TLG) of the primary tumour (PT), index-node (IN) (lymph node with highest TLG), total-lymph-nodes (TN) and combined primary-tumour and nodal (PTN), and their % reductions in iPET were analysed, and results were correlated with 2-year Kaplan-Meier loco-recurrence-free-survival (LRFS), regional-failure-free-survival (RFFS), distant-metastatic-failure-free-survival (DMFFS), disease-free-survival (DFS), and overall-survival (OS). Optimal-cutoffs (OC) were derived from Receiver-Operating-Characteristic curves.

RESULTS

For LRFS, the only predictor was reduction in PT MTV by >50%: 95.2% vs. 75.0%, p=0.024. For other treatment outcomes, only nodal or PTN predicted outcomes. The IN SUVmax (pre-PET-OC=10.45g/mL and iPET-OC=8.15) and TLG (prePET-OC=90g and iPET-OC=33.4) were the best predictors of outcome: RFFS (iPET SUVmax/TLG): 100% vs. 50%, p<0.001 and 100% vs. 44%, p=0.032; DMFFS (prePET SUVmax/TLG); 100% vs. 51.9%, p=0.004 and 100% vs. 47.6%, p=0.002; DFS (prePET TLG and iPET SUVmax): 87.5% vs. 33%, p=0.045 and 78.7% vs. 20%, p=0.01; and OS (prePET TLG): 100% vs 66.3%, p=0.036.

CONCLUSIONS

We have demonstrated IN of prePET and iPET to be a feasible and potentially useful novel imaging biomarker to predict for patients with NPC who have a high risk of regional or distant metastatic failure. Future work is required to validate our findings in a well-powered, prospective study with a standardised treatment protocol, and their potential use to guide individualised therapy for NPC.

18F-FDG PET-CT performed before and during radiation therapy of head and neck squamous cell carcinoma: Are they independent or complementary to each other?

INTRODUCTION

The aims of this study are to evaluate the prognostic value of metabolic parameters derived from (18) F-FDG PET-CT performed before definitive radiation therapy (RT) (prePET) in patients with mucosal primary head and neck squamous cell carcinoma (MPHNSCC) and to assess the additive prognostic values of FDG PET-CT performed during RT (iPET).

METHODS

One hundred patients with MPHNSCC treated with radical RT underwent staging prePET and iPET performed during the third week of treatment. The maximum standardized uptake value (SUVmax ), metabolic tumour volume (MTV) and total lesional glycolysis (TLG) of primary tumour were analysed for both prePET and iPET, and results were correlated with loco-regional recurrence-free survival (LRFS), disease-free survival (DFS), metastatic failure-free survival (MFFS) and overall survival (OS), using Kaplan-Meier analysis. Optimal cut-offs (OC) for prePET and iPET were derived from Receiver Operating Characteristic curves. Patients with metabolic parameters above/below the individual OC of prePET as well as iPET (i.e. combined prePET and iPET (comPET)) were evaluated against their outcomes.

RESULTS

Median age was 61 years (range 39-81), median follow-up of 20 months (range 4-70, mean 27), and AJCC 7th Edition clinical stage II, III and IV were 8, 24 and 68 patients respectively. Metabolic values below individual OC in comPET were found to be associated with statistically significant improvements (P < 0.05) in DFS, LRFS and OS. In addition, patients with SUVmax above the OC in comPET were associated with worse MFFS (P = 0.011) and confirmed on both univariate (P = 0.019) and multivariate analyses (P = 0.04).

CONCLUSION

Addition of iPET significantly improves the prognostic values of all three metabolic parameters and can potentially be used in future adaptive local and systemic therapy trials.

Correlation between Semi-Quantitative (18)F-FDG PET/CT Parameters and Ki-67 Expression in Small Cell Lung Cancer

PURPOSE

The aim of this study was to evaluate the relationship between semiquantitative parameters on (18)F-FDG PET/CT including maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) and the expression level of Ki-67 in small-cell lung cancer (SCLC).

METHODS

Ninety-four consecutive patients with SCLC were enrolled in this study. They underwent (18)F-FDG PET/CT for initial evaluation of SCLC, and we measured SUVmax, avgSUVmean, MTVsum, and TLGtotal on (18)F-FDG PET/CT images. The protein expression of Ki-67 was examined by immunohistochemical staining.

RESULTS

Significant correlations were found between the MTVsum and Ki-67 labeling index (r = 0.254, p = 0.014) and the TLGtotal and Ki-67 labeling index (r = 0.239, p = 0.020). No correlation was found between the SUVmax and Ki-67 labeling index (r = 0.116, p = 0.264) and the avgSUVmean and Ki-67 labeling index (r = 0.031, p = 0.770). Dividing the Ki-67 expression level into three categories, it was suggested that increasing Ki-67 expression level caused a stepwise increase in the MTVsum and TLGtotal. (p = 0.028 and 0.039, respectively), but not the SUVmax and avgSUVmean (p = 0.526 and 0.729, respectively).

CONCLUSION

In conclusion, the volume-based parameters of (18)F-FDG PET/CT correlate with immunohistochemical staining of Ki-67 in SCLC. Measurement of the MTVsum and TLGtotal by (18)F-FDG PET/CT might be a simple, noninvasive, and useful method to determine the proliferative potential of cancer cells.

[F-18] FDG-PET/CT parameters as predictors of outcome in inoperable NSCLC patients

Background

We evaluated the prognostic significance of standardized uptake value (SUVmax), metabolic tumour volume (MTV), and total lesion glycolysis (TLG) in [F-18] FDG PET/CT findings in patients with inoperable non-small-cell lung cancer (NSCLC).

Patients and methods.

One hundred and three patients (mean age, 65.6 ± 16 years) underwent [F-18] FDG PET/CT before the chemotherapy. The SUVmax value, the MTV (cm³; 42% threshold) and the TLG (g) were registered. The patients were followed up to 18 months thereafter (range 12–55 months). Failure to respond without progression, progression and/or disease-related death constituted surrogate end-points. The optimal SUVmax, MTV and TLG cut-off to predict the patients’ outcome were estimated. PET/CT results were then related to disease outcome (progression free survival; PFS).

Results

The Kaplan-Meier survival analysis for SUVmax showed a significant shorter PFS in patients presenting with lower values as compared to those with higher (p < 0.05, log-rank test). MTV and TLG were not suitable for predicting PFS apart from the subset of patients with mediastinal nodal involvement.

Conclusions

Despite the availability of new tools for the quantitative assessment of disease activity on PET/CT, the SUVmax rather than MTV and TLG remains the only predictor for PFS in NSCLC patients. MTV holds a value only when concomitant nodal involvement occurs.

Association between serum tumor markers and metabolic tumor volume or total lesion glycolysis in patients with recurrent small cell lung cancer

The aim of the present study was to investigate the association between serum tumor markers and the metabolic tumor volume (MTV) or total lesion glycolysis (TLG), as determined by fluorine-18 fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography-computed tomography (PET/CT) in patients with recurrent small cell lung cancer (SCLC). Data from 21 patients with recurrent SCLC were collected. The levels of neuron-specific enolase (NSE), carcinoembryonic antigen (CEA) and cytokeratin 19 fragment 21-1 were measured at the time of the ¹⁸F-FDG PET/CT examination. The MTV and TLG of all lesions were calculated. Pearson correlation analyses were used to estimate the correlations between NSE level and PET findings. Pearson correlation analyses showed that NSE was the only tumor marker to have a strong correlation with MTV or TLG (r=0.787, P<0.001; r=0.866, P<0.001, respectively). In patients with a normal NSE level, no correlation was found between NSE and MTV or TLG (r=0.018, P=0.958; r=-0.003, P=0.92, respectively), but a significant correlation was found in patients with an abnormal NSE level (r=0.789, P<0.01; r=0.872, P=0.01, respectively). Therefore, TLG and MTV may serve as sensitive markers of tumor burden in patients with recurrent SCLC, with TLG showing greater sensitivity. In patients with an abnormal NSE level, a higher NSE level indicates greater MTV and TLG.

Prognostic Value of (18)F-FDG PET-CT in Nasopharyngeal Carcinoma: Is Dynamic Scanning Helpful?

OBJECTIVES

To evaluate the differences in prognostic values of static and dynamic PET-CT in nasopharyngeal carcinoma (NPC).

MATERIAL AND METHODS

Forty-five patients who had static scan were recruited. Sixteen had dynamic scan. The primary lesions were delineated from standardized uptake value (SUV) maps from static scan and K i maps from dynamic scan. The average follow-up lasted for 34 months. The patients who died or those with recurrence/residual disease were considered "poor outcome"; otherwise they were considered "good outcome." Fisher's exact test and ROC analysis were used to evaluate the prognostic value of various factors.

RESULTS

Tumor volume thresholded by 40% of maximal SUV (VOLSUV40) significantly predicted treatment outcome (p = 0.024) in the whole cohort. In 16 patients with dynamic scan, all parameters by dynamic scan were insignificant in predicting the outcome. The combination of maximal SUV, maximal K i , VOLSUV40, and VOL K i 37 (the tumor volume thresholded by 37% maximal K i ) achieved the highest predicting accuracy for treatment outcome with sensitivity, specificity, and accuracy of 100% in these 16 patients; however this improvement compared to VOLSUV40 was insignificant.

CONCLUSION

Tumor volume from static scan is useful in NPC prognosis. However, the role of dynamic scanning was not justified in this small cohort.

Positron emission tomography-computed tomography before treatment is highly prognostic of distant metastasis in nasopharyngeal carcinoma patients after intensity-modulated radiotherapy treatment: a prospective study with long-term follow-up

OBJECTIVES

The utility of [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET) in the prediction of distant metastasis after definitive treatment for non-disseminated NPC patients is not clear. We prospectively investigated the prognostic significance of (18)F-FDG PET-CT performed before treatment for the distant metastasis-free survival (DMFS) of NPC patients treated with intensity-modulated radiotherapy (IMRT) ± chemotherapy.

MATERIALS AND METHODS

The results of PET-CT scans performed at initial diagnosis were recorded and analyzed prospectively. Patients then received standard treatment per protocol independent of the PET-CT result. IMRT was administered to the nasopharynx and neck. Early stage patients received IMRT alone, whereas loco-regionally advanced patients received concurrent chemoradiation. Patient outcomes were evaluated.

RESULTS

One hundred and seventy-nine patients were analyzable. DM occurred in 33 patients and the 3-year DMFS rate of the whole cohort was 84.1%. The cut-off of the SUVmax at the primary site (SUVmax-P) for DMFS was 10.22 by ROC curve. The 3-year DMFS rates of the higher and lower SUVmax-P groups (SUVmax-P⩽or>10.22) were 93.2% and 75.1%, respectively, with an 18.1% difference (P=0.003). Multivariate analysis indicated that SUVmax-P was a risk factor independently associated with DMFS (HR, 2.672; 95%CI, 1.236-5.776; P=0.012) and OS (HR, 2.417; 95%CI, 1.313-4.448; P=0.005). Subgroup analysis indicated that the 5-year DMFS and OS in loco-regionally advanced patients with SUVmax-P⩽10.22 were similar to those of early stage patients, whereas those of loco-regionally advanced patients with SUVmax-P>10.22 patients predicted worse outcome.

CONCLUSION

SUVmax-P is a useful biomarker to predict distant metastasis of NPC patients treated with IMRT. Combining SUVmax-P with tumor overall stage, a more precise picture could be obtained to predict treatment outcome.

Pretreatment (18)F-FDG uptake heterogeneity can predict survival in patients with locally advanced nasopharyngeal carcinoma--a retrospective study

BACKGROUND

Intratumoural heterogeneity has been demonstrated to be a strong indicator of malignant transformation. Our study was to investigate pretreatment (18)F-FDG parameters, including (18)F-FDG based heterogeneity for predicting survival in patients with locally advanced nasopharyngeal carcinoma (NPC).

METHODS

Forty newly diagnosed, biopsy-proven locally advanced NPC patients who underwent (18)F-FDG PET/CT were retrospectively included. The following PET parameters were assessed: maximum and mean standardised uptake value (SUVmax and SUVmean), metabolic tumour volume (MTV), total lesion glycolysis (TLG) and intratumoral heterogeneity index (HI). The previous parameters were recorded both for the primary tumor (-T) and neck lymph nodes (-N). The following endpoints were evaluated: local control (LC), progression-free survival (PFS) and overall survival (OS). The survival analyses were performed using the Kaplan-Meier method. Univariate analysis was performed using the log-rank test.

RESULTS

Patients with a lower HI-T, SUVmax-T, SUVmean-T and TLG-T had significantly better 2-year LC. In predicting PFS, we found that both lower HI-T and HI-N had significantly better prognosis. However, the OS was only statistically associated with HI-T.

CONCLUSION

(18)F-FDG based heterogeneity appears to be an potential predicator of patient survival after treatment.

Prognostic value of FDG PET metabolic tumor volume in human papillomavirus-positive stage III and IV oropharyngeal squamous cell carcinoma

OBJECTIVE

The purpose of this study was to establish the prognostic utility in human papillomavirus (HPV)-positive stage III and IV oropharyngeal squamous cell carcinoma (SCC) of the (18)F-FDG parameters maximal, mean, and peak standardized uptake value (SUVmax, SUVmean, and SUVpeak, respectively); metabolic tumor volume (MTV); and total lesion glycolysis (TLG).

MATERIALS AND METHODS

We included 70 patients in the present study who had a biopsy-proven HPV-positive (by in situ hybridization) stage III and IV oropharyngeal SCC and had a baseline PET/CT examination at our institution. Outcome endpoint was event-free survival (EFS), which included recurrence-free and overall survival. Cox proportional hazards multivariate regression analyses were performed. Survival analysis was performed using Kaplan-Meier survival curves.

RESULTS

In Cox regression proportional hazard univariate analysis, total MTV (hazard ratio [HR], 1.02; p = 0.008), primary-tumor MTV (HR, 1.02; p = 0.024), neck nodal MTV (HR, 1.03; p = 0.006), neck nodal TLG (HR, 1.01; p = 0.006), and neck node status (HR, 4.45; p = 0.03) showed a statistically significant association with EFS. There was no statistically significant association of EFS with SUVmax, SUVmean, SUVpeak, and primary-tumor or overall TLG. In Cox regression proportional hazard multivariate model I, total MTV remained an independent prognostic marker for EFS when adjusted for every other variable individually in the model; in model II, primary-tumor MTV, neck node status, and SUVpeak are independent prognostic markers for EFS. The Kaplan-Meier survival curves using optimum cut point of 41 mL of total MTV were not significant (p = 0.09).

CONCLUSION

Total MTV and primary-tumor MTV are associated with survival outcomes in patients with HPV-positive stage III and IV oropharyngeal SCC.

Metabolic tumour volume as a prognostic factor for oral cavity squamous cell carcinoma treated with primary surgery

Background

Metabolic tumour volume (MTV) obtained from pre-treatment ¹⁸ F-fluorodeoxydeglucose positron emission tomography with computed tomography (PET-CT) has been validated as an independent predictive factor of outcomes in head and neck cancer patients (HNC) treated with primary chemoradiotherapy (CRT). However its role in patients treated with primary surgery has not yet been studied.

Objective

To evaluate the prognostic value of MTV in patients treated with primary surgery for oral cavity squamous cell carcinoma (OCSCC).

Method

Demographic and survival data was obtained from patients diagnosed with OCSCC from 2008–2012 in Alberta, Canada. All patients included in the study had PET-CT scan before curative surgical resection. MTV and maximum standardized uptake value (SUV_max) value was delineated from pre-treatment PET-CT scans using Segami Oasis software (Columbus, OH). MTV and SUV_max were divided into intertertile thirds before statistical analysis to allow for in-group comparison of survival.

Results

A total of 80 patients were analyzed using SPSS ver. 20.0 (SPSS Inc, Chicago, IL). Five-year overall, and disease-free survival using Kaplan-Meier curves were 70% and 73% respectively. When the combined SUV_max (tumour primary and locoregional metastasis) was evaluated, it failed to predict overall (HR = 1.0, p = 0.99) or disease-free survival (HR = 1.0, p = 0.227).

Conversely an increase in MTV of 17.5 mL (difference between the highest and lowest MTV tertile) was associated with a 12.4 fold increase in risk of disease recurrence (p < 0.001) and an 11.2 fold increase in the risk of death (p < 0.05).

Conclusions

This study shows that MTV is an independent adverse prognostic factor for death and disease recurrence in OCSCC treated with primary surgery.

Prognostic value of metabolic tumor volume as measured by fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography in nasopharyngeal carcinoma

BACKGROUND

The prognostic value of the tumor burden characterized by the metabolic tumor volume (MTV) remains under investigation in nasopharyngeal carcinoma (NPC). The purpose of this study was to evaluate the prognostic value of the maximum standardized uptake value (SUVmax ) and MTV according to metabolic volume threshold as measured by positron emission tomography (PET)/computed tomography (CT), and other clinical factors, in patients with NPC.

METHODS

This study was a retrospective chart review. We evaluated the association of SUVmax , MTV2.5 , MTV3.0 , and other clinical factors with overall survival (OS) using Kaplan-Meier and Cox regression models. (MTV2.5 and MTV3.0 are the volume of hypermetabolic tissue within the regions of gross tumor volumes with a SUV value greater than the threshold values of 2.5 and 3.0, respectively.)

RESULTS

Higher MTV2.5 of 31.45 cm(3) and MTV3.0 of 23.01 cm(3) were associated with an increased risk of death (hazard ratio [HR] = 5.028; p = 0.029), although no significant relationship was found between SUVmax and OS. Interestingly, MTV3.0 was associated with OS in both the differentiated and undifferentiated groups, although MTV2.5 was only associated with OS in the undifferentiated group. Among the clinical parameters, only radiotherapy was associated with longer OS (HR = 12.124; p < 0.001).

CONCLUSION

The MTV and radiotherapy could be prognostic values associated with OS. Particularly, MTV2.5 and MTV3.0 might be valuable metabolic parameters for predicting long-term survival in patients with NPC. Furthermore, MTV3.0 may be more useful because it can be applied irrespective of pathologic subtype.

Adding maximum standard uptake value of primary lesion and lymph nodes in 18F-fluorodeoxyglucose PET helps predict distant metastasis in patients with nasopharyngeal carcinoma

Objective

To find out the most valuable parameter of ¹⁸F-Fluorodeoxyglucose positron emission tomography for predicting distant metastasis in nasopharyngeal carcinoma.

Methods

From June 2007 through December 2010, 43 non-metastatic NPC patients who underwent ¹⁸F-Fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) before radical Intensity-Modulated Radiation Therapy were enrolled and reviewed retrospectively. PET parameters including maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean), metabolic tumor volume (MTV), and total lesion glucose (TLG) of both primary tumor and cervical lymph nodes were calculated. Total SUVmax were recorded as the sum of SUVmax of primary tumor and cervical lymph nodes. Total SUVmean, Total MTV and Total TLG were calculated in the same way as Total SUVmax.

Results

The median follow-up was 32 months (range, 23–68 months). Distant metastasis was the main pattern of treatment failure. Univariate analysis showed higher SUVmax, SUVmean, MTV, and TLG of primary tumor, Total SUVmax, Total MTV, Total TLG, and stage T3-4 were factors predicting for significantly poorer distant metastasis-free survival (p = 0.042, p = 0.008, p = 0.023, p = 0.023, p = 0.024, p = 0.033, p = 0.016, p = 0.015). In multivariate analysis, Total SUVmax was the independent predictive factor for distant metastasis (p = 0.046). Spearman Rank correlation analysis showed mediate to strong correlationship between Total SUVmax and SUVmax-T, and between Total SUVmax and SUVmax-N(Spearman coefficient:0.568 and 0.834;p = 0.000 and p = 0.000).

Conclusions

Preliminary results indicated that Total SUVmax was an independently predictive factor for distant metastasis in patients of nasopharyngeal carcinoma treated with Intensity-Modulated Radiation Therapy.

Estimate of the impact of FDG-avidity on the dose required for head and neck radiotherapy local control

Background and purpose

Although FDG-avid tumors are recognized as a potential target for dose escalation, there is no clear basis for selecting a boost dose to counter this apparent radioresistance. Using a novel analysis method, based on the new concept of an outcome-equivalent dose, we estimate the extra dose required to equalize local control between FDG-avid and non-avid head and neck tumors.

Materials and methods

Based on a literature review, five reports of head and neck cancer (423 patients in total), along with an internal validation dataset from our institution (135 oropharynx patients), were used in this analysis. To compensate for the heterogeneity among multi-institutional patient cohorts and corresponding treatment techniques, local control data of the cohorts were fit to a single dose–response curve with a clinically representative steepness (γ₅₀ = 2), thereby defining an ‘outcome-equivalent dose’ (OED) for each institutional cohort. Separate dose–response curves were then determined for the FDG-avid and FDG-non-avid patient cohorts, and the ratio of TD₅₀ (tumor dose required for 50% of control) values between the high- and low-FDG-uptake groups (TD_50,high/TD_50,low) was estimated, resulting in an estimated metabolic dose-modifying factor (mDMF) due to FDG-avidity.

Results

For individual datasets, the estimated mDMFs were found to be in the range of 1.07–1.62, decreasing if the assumed slope (γ₅₀) increased. Weighted logistic regression for the six datasets resulted in a mDMF of 1.19 [95% CI: 1.04–1.34] for a γ₅₀ value of 2, which translates to a needed dose increase of about 1.5 Gy per unit increase in the maximum standardized uptake value (SUV_m) of FDG-PET [95% CI: 0.3–2.7]. Assumptions of lower or higher γ₅₀ values (1.5 or 2.5) resulted in slightly different mDMFs: 1.26 or 1.15, respectively. A validation analysis with seven additional datasets, based on relaxed criteria, was consistent with the estimated mDMF.

Conclusions

We introduced a novel outcome-equivalent dose analysis method to estimate the dose– response modifying effect of FDG uptake variation. To reach equal response rates, FDG-avid tumors are likely to require 10% to 30% more dose than FDG-non-avid tumors. These estimates provide a rational starting point for selecting IMRT boosts for FDG-avid tumors. However, independent tests and refinements of the estimated dose-modifying effect, using high-quality prospective clinical trial data, are needed.

Prognostic value of 18F-FDG PET/CT in patients with soft tissue sarcoma: comparisons between metabolic parameters

OBJECTIVES

To investigate the relationship between volume-based PET parameters and prognosis in patients with soft tissue sarcoma (STS).

METHODS

We retrospectively reviewed 55 patients with pathologically proven STS who underwent pretreatment with (18) F-Fluorodeoxyglucose ((18)F-FDG) PET/CT. The maximum standardized uptake value (SUVmax), average SUV (SUVavg), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of primary tumors were measured using a threshold SUV as liver activity for determining the boundary of tumors. Univariate and multivariate survival analyses for overall survival were performed according to the metabolic parameters and other clinical variables.

RESULTS

Cancer-related death occurred in 19 of 55 patients (35 %) during the follow-up period (29 ± 23 months). On univariate analysis, AJCC stage (stage IV vs. I-III, hazard ratio (HR) = 2.837, p = 0.028), necrosis (G2 vs. G0-G1, HR = 3.890, p = 0.004), SUVmax (1 unit - increase, HR = 1.146, p = 0.008), SUVavg (1 unit - increase, HR = 1.469, p = 0.032) and treatment modality (non-surgical therapy vs. surgery, HR = 4.467, p = 0.002) were significant predictors for overall survival. On multivariate analyses, SUVmax (HR = 1.274, p = 0.015), treatment modality (HR = 3.353, p = 0.019) and necrosis (HR = 5.985, p = 0.006) were identified as significant independent prognostic factors associated with decreased overall survival.

CONCLUSIONS

The SUVmax of the primary tumor is a significant independent metabolic prognostic factor for overall survival in patients with STS. Volume-based PET parameters may not add prognostic information outside of the SUVmax.

Prognostic value of metabolic tumor volume and total lesion glycolysis in head and neck cancer: a systematic review and meta-analysis

We conducted a comprehensive systematic review of the literature on volumetric parameters and a meta-analysis of the prognostic value of metabolic tumor volume (MTV) and total lesion glycolysis (TLG) in patients with head and neck cancer (HNC).

METHODS

A systematic search of MEDLINE and EMBASE was performed using the key words PET, head and neck, and volume. Inclusion criteria were (18)F-FDG PET used as an initial imaging tool; studies limited to HNC; patients who had not undergone surgery, chemotherapy, or radiotherapy before PET scans; and studies reporting survival data. Event-free survival and overall survival were considered markers of outcome. The impact of MTV or TLG on survival was measured by the effect size hazard ratio (HR). Data from each study were analyzed using Review Manager.

RESULTS

Thirteen studies comprising 1,180 patients were included in this study. The combined HR for adverse events was 3.06 (2.33-4.01, P < 0.00001) with MTV and 3.10 (2.27-4.24, P < 0.00001) with TLG, meaning that tumors with high volumetric parameters were associated with progression or recurrence. Regarding overall survival, the pooled HR was 3.51 (2.62-4.72, P < 0.00001) with MTV and 3.14 (2.24-4.40, P < 0.00001) with TLG. There was no evidence of significant statistical heterogeneity at an I(2) of 0%.

CONCLUSION

MTV and TLG are prognostic predictors of outcome in patients with HNC. Despite clinically heterogeneous HNC and the various methods adopted between studies, we can confirm that patients with a high MTV or TLG have a higher risk of adverse events or death.

Predictive value of volumetric parameters measured by F-18 FDG PET/CT for lymph node status in patients with surgically resected rectal cancer

OBJECTIVE

The objective of this study was to investigate the predictive role of volumetric parameters such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG) measured by F-18 FDG PET/CT for regional lymph node (rLN) metastasis in rectal cancer patients.

METHODS

Retrospectively, 74 rectal cancer patients were enrolled. All patients received surgical treatment and F-18 FDG PET/CT at diagnosis. The F-18 FDG PET/CT findings of primary cancer and rLN involvement were compared with the pathologic diagnosis within 5 weeks after operation. Univariate and multivariate analyses were used to analyze the associations among the pathologic LN status and age, sex, T stage, AJCC stage, SUVmax, lymphatic invasion, venous invasion, neural invasion, and volumetric parameters.

RESULTS

The LN (+) group showed statistically significant higher values of MTV2.5 (p < 0.0001), MTV3 (p < 0.0001), MTV3.5 (p = 0.0001), TLG2.5 (p = 0.0007), TLG3 (p = 0.0011), and TLG3.5 (p = 0.0024). In univariate analysis, T stage, AJCC stage, neural invasion, and volumetric parameters were factors significantly associated with pathologic LN involvement. However, in multivariate analysis, advanced T stage, high AJCC stage, MTV2.5, and TLG2.5 were associated with pathologic LN involvement in rectal cancer.

CONCLUSION

This study showed that, not only T stage and AJCC stage, but also volumetric parameters such as MTV2.5 and TLG2.5 are useful factors for the prediction of pathologic LN status in rectal cancer patients.

Incorporating prognostic imaging biomarkers into clinical practice

A prognostic imaging biomarker can be defined as an imaging characteristic that is objectively measurable and provides information on the likely outcome of the cancer disease in an untreated individual and should be distinguished from predictive imaging biomarkers and imaging markers of response. A range of tumour characteristics of potential prognostic value can be measured using a variety imaging modalities. However, none has currently been adopted into routine clinical practice. This article considers key examples of emerging prognostic imaging biomarkers and proposes an evaluation framework that aims to demonstrate clinical efficacy and so support their introduction into the clinical arena. With appropriate validation within an established evaluation framework, prognostic imaging biomarkers have the potential to contribute to individualized cancer care, in some cases reducing the financial burden of expensive cancer treatments by facilitating their more rational use.

Predictive value of primary fluorine-18 fluorodeoxyglucose standard uptake value for a better choice of systematic nodal dissection or sampling in clinical stage ia non--small-cell lung cancer

PURPOSE

To determine whether the standard uptake value (SUV) of the primary lesion can predict mediastinal lymph node metastasis in clinical stage IA non--small-cell lung cancer (NSCLC).

MATERIALS AND METHODS

At 5 centers, patients with clinical stage IA NSCLC from February 2004 to August 2010 were analyzed retrospectively. Data from Shandong Cancer Hospital and from the Cancer Hospital Affiliated to Harbin Medical University were used as a testing set, and data from the other 3 institutions were used as the validation set. Final diagnosis was established based on the histopathologic examination.

RESULTS

Data from 144 patients were collected for the study. The primary results in our study showed that maximal SUV (SUVmax) of primary tumor might be a predictor of lymph node metastasis (χ(2) = 10.424; P = .001) and the best cutoff value was 7.25 (P = .029). For the testing set, lymph node metastasis rates in low-grade group (SUVmax < 7.25) and high-grade group (SUVmax > 7.25) were 5% (2/43) and 36% (9/25) (P = .001) For the total data set, lymph node metastasis rate was 7% (6/93) in low-grade group (SUVmax < 7.25) and 26% (13/51) in high-grade group (SUVmax > 7.25) (χ(2)= 10.424; P = .001). A multivariate analysis revealed that no factors were applied to predict the probability of metastasis. But the analysis showed a weak correlation between SUVmax and nodal status (r = 0.21; P = .011) with bivariate correlation.

CONCLUSION

Analysis of our data suggested that fluorine-18 fluorodeoxyglucose SUVmax of the primary tumor might be a predictor of lymph node involvement in stage IA NSCLC. The rate of mediastinal lymph node metastasis of patients with a lower fluorine-18 fluorodeoxyglucose positron emission tomography-computed tomography SUVmax might be relatively low, which provides more evidence for clinical procedures of clinical stage IA NSCLC.