Prognostic value of serial [18F]fluorodeoxyglucose PET-CT uptake in stage III patients with non-small cell lung cancer treated by concurrent chemoradiotherapy

Clinical Effects of PET-CT Before Definite Concurrent Chemoradiotherapy in Patients With Unresectable Stage IIIA-IIIB Squamous Cell Carcinoma of the Lungs

PURPOSE

No large-scale, retrospective cohort study with a long-term follow-up time has yet evaluated the effects of preoperative 18 F-FDG PET-CT on survival in patients with unresectable stages IIIA-IIIB squamous cell lung carcinoma (SqCLC) who received definite concurrent chemoradiotherapy (CCRT).

METHODS

We included patients with unresectable stages IIIA-IIIB SqCLC receiving definite CCRT and categorized them into 2 groups. The case group comprised patients who underwent pre-CCRT 18 F-FDG PET-CT, and the comparison group comprised patients who did not receive pre-CCRT 18 F-FDG PET-CT; the groups were matched at a ratio of 1:1.

RESULTS

The matching process yielded a final cohort of 4042 eligible patients (2021 and 2021 in the case and comparison groups, respectively). Multivariable Cox regression analyses revealed a positive correlation between patients with unresectable stages IIIA-IIIB SqCLC receiving definite CCRT and all-cause death in the pre-CCRT 18 F-FDG PET-CT (adjusted hazard ratio, 0.85; 95% confidence interval, 0.80-0.91; P < 0.0001).

CONCLUSION

Pre-CCRT 18 F-FDG PET-CT was associated with more favorable survival in both patients with unresectable clinical stage IIIA and those with stage IIIB receiving definite CCRT.

Predictive value of interim 18F-FDG-PET in patients with non-small cell lung cancer treated with definitive radiation therapy

PURPOSE

We evaluated that early metabolic response determined by 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) during radiotherapy (RT), predicts outcomes in non-small cell lung cancer.

MATERIAL AND METHODS

Twenty-eight patients evaluated using pretreatment 18F-FDG-PET/CT (PETpre) and interim 18F-FDG-PET/CT (PETinterim) after 11 fractions of RT were retrospectively reviewed. Maximum standardized uptake value (SUVmax) was calculated for primary lesion. Predictive value of gross tumor volume (ΔGTV) and SUVmax (ΔSUVmax) changes was evaluated for locoregional control (LRC), distant failure (DF), and overall survival (OS). Metabolic responders were patients with ΔSUVmax >40%.

RESULTS

Metabolic responders showed better trends in 1-year LRC (90.9%) than non-responders (47.1%) (p = 0.086). Patients with large GTVpre (≥120 cc) demonstrated poor LRC (hazard ratio 4.14, p = 0.022), while metabolic non-responders with small GTVpre (<120 cc) and metabolic responders with large GTVpre both had 1-year LRC rates of 75.0%. Reduction of 25% in GTV was not associated with LRC; however, metabolic responders without a GTV response showed better 1-year LRC (83.3%) than metabolic non-responders with a reduction in GTV (42.9%). Metabolic responders showed lower 1-year DF (16.7%) than non-responders (50.0%) (p = 0.025). An ΔSUVmax threshold of 40% yielded accuracy of 64% for predicting LRC, 75% for DF, and 54% for OS. However, ΔGTV > 25% demonstrated inferior diagnostic values than metabolic response.

CONCLUSIONS

Changes in tumor metabolism diagnosed using PETinterim during RT better predicted treatment responses, recurrences, and prognosis than other factors historically used.

Prediction of FDG-PET stage and uptake for non-small cell lung cancer on non-contrast enhanced CT scans via fractal analysis

PURPOSE

To investigate whether the FD of non-small cell lung cancer (NSCLC) on CT predicts tumor stage and uptake on ¹⁸F-fluorodeoxyglucose positron emission tomography.

MATERIAL AND METHODS

The FD within a tumor region was determined using a box counting algorithm and compared to the lymph node involvement (NI) and metastatic involvement (MI) and overall stage as determined from PET. A Mann-Whitney U test was applied to the extracted FD features for the NI and the MI.

RESULTS

The two tests showed good significance with p < .05 (p_NI = 0.0139, p_MI = 0.0194). Also after performing fractal analysis to all cases, it was found that for those who had a CT of stage I or II had a higher likelihood of the NI and/or MI stage being upstaged by PET, Odds Ratio 5.38 (95% CI 0.99-29.3). For those who are CT stage III or IV had an increased likelihood of the NI and/or MI stage being down staged by PET, Odds Ratio: 7.33 (95% CI 0.48-111.2).

CONCLUSION

Initial results of this study indicate higher FD in CT images of NSCLC is associated with advanced stage and greater FDG uptake on PET. Measurements of tumor fractal analysis on conventional non-contrast CT examinations could potentially be used as a prognostic marker and/or to select patients for PET.

18F-FDG PET/CT in Restaging and Evaluation of Response to Therapy in Lung Cancer: State of the Art

BACKGROUND

Metabolic information provided by 18F-FDG PET/CT are useful for initial staging, therapy planning, response evaluation, and to a lesser extent for the follow-up of non-small cell lung cancer (NSCLC). To date, there are no established clinical guidelines in treatment response and early detection of recurrence.

OBJECTIVE

To provide an overview of 18F-FDG PET/CT in NSCLC and in particular, to discuss its utility in treatment response evaluation and restaging of lung cancer.

METHODS

A comprehensive search was used based on PubMed results. From all studies published in English those that explored the role of 18F-FDG PET/CT in the treatment response scenario were selected.

RESULTS

Several studies have demonstrated that modifications in metabolic activity, expressed by changes in SUV both in the primary tumor as well as in regional lymph nodes, are associated with tumor response and survival. Beside SUV, other metabolic parameters (i.e. MTV, TLG, and percentage changes) are emerging to be helpful for predicting clinical outcomes.

CONCLUSION

18F-FDG parameters appear to be promising factors for evaluating treatment response and for detecting recurrences, although larger prospective trials are needed to confirm these evidences and to determine optimal cut-off values.

Prognostic value of volumetric metabolic parameter changes determined by during and after radiotherapy-based 18 F-FDG PET/CT in stage III non-small cell lung cancer

The aim of this prospective study was to evaluate the prognostic value of volumetric metabolic parameters assessed by during and after radiation-based therapy ¹⁸ F-FDG PET/CT in patients with stage III non-small cell lung cancer (NSCLC). We enrolled stage III NSCLC patients who had planned to receive definitive chemo-radiation or radiotherapy (RT) and underwent ¹⁸ F-FDG PET/CT before treatment (PET1), during RT (at the fifth week, PET2) and after treatment (3 months later, PET3). By comparing with PET1, percentage changes of metabolic tumor volume (ΔMTV) and tumor total lesion glycolysis (ΔTLG) of PET2 and PET3 were calculated. We used medians of ΔTLG and ΔMTV as cut-off values to stratify patients. Their prognostic values were evaluated by progression-free survival (PFS) and overall survival (OS). Thirty patients were enrolled initially. Five were excluded due to multiple metastases or double cancer. The remaining 25 patients had PET2 at a median of 46 Gy. Data on PET3 were available in 19 patients. During-RT ΔTLG (cut-off: 65%) was a significant prognostic factor for PFS (P = 0.02) and OS (P < 0.01). During-RT ΔMTV (cut-off: 42%) had marginal significance for PFS (P = 0.07) and was significant for OS (P = 0.02). Of the PET3 parameters, neither ΔTLG nor ΔMTV was a significant prognostic factor for PFS and OS. We conclude that ΔTLG of during-RT ¹⁸ F-FDG PET/CT may predict treatment response and thus provide opportunities to modify treatment for poor responders.

Role of interim 18F-FDG-PET/CT for the early prediction of clinical outcomes of Non-Small Cell Lung Cancer (NSCLC) during radiotherapy or chemo-radiotherapy. A systematic review

BACKGROUND

Non-Small Cell Lung Cancer (NSCLC) is characterized by aggressiveness and includes the majority of thorax malignancies. The possibility of early stratification of patients as responsive and non-responsive to radiotherapy with a non-invasive method is extremely appealing. The distribution of the Fluorodeoxyglucose (¹⁸F-FDG) in tumours, provided by Positron-Emission-Tomography (PET) images, has been proved to be useful to assess the initial staging of the disease, recurrence, and response to chemotherapy and chemo-radiotherapy (CRT).

OBJECTIVES

In the last years, particular efforts have been focused on the possibility of using ad interim ¹⁸F-FDG PET (FDG_int) to evaluate response already in the course of radiotherapy. However, controversial findings have been reported for various malignancies, although several results would support the use of FDG_int for individual therapeutic decisions, at least in some pathologies. The objective of the present review is to assemble comprehensively the literature concerning NSCLC, to evaluate where and whether FDG_int may offer predictive potential.

METHODS

Several searches were completed on Medline and the Embase database, combining different keywords. Original papers published in the English language from 2005 to 2016 with studies involving FDG_int in patients affected by NSCLC and treated with radiation therapy or chemo-radiotherapy only were chosen.

RESULTS

Twenty-one studies out of 970 in Pubmed and 1256 in Embase were selected, reporting on 627 patients.

CONCLUSION

Certainly, the lack of univocal PET parameters was identified as a major drawback, while standardization would be required for best practice. In any case, all these papers denoted FDG_int as promising and a challenging examination for early assessment of outcomes during CRT, sustaining its predictivity in lung cancer.

Local Radiotherapy Intensification for Locally Advanced Non-small-cell Lung Cancer - A Call to Arms

Chemoradiotherapy, the standard of care for locally advanced non-small-cell lung cancer (NSCLC), often fails to eradicate all known disease. Despite advances in chemotherapeutic regimens, locally advanced NSCLC remains a difficult disease to treat, and locoregional failure remains common. Improved radiographic detection can identify patients at significant risk of locoregional failure after definitive treatment, and newer methods of escalating locoregional treatment may allow for improvements in locoregional control with acceptable toxicity. This review addresses critical issues in escalating local therapy, focusing on using serial positron emission tomography-computed tomography to select high-risk patients and employing stereotactic radiotherapy to intensify treatment. We further propose a clinical trial concept that incorporates the review's findings.

Evolution of [18F]fluorodeoxyglucose and [18F]fluoroazomycin arabinoside PET uptake distributions in lung tumours during radiation therapy

BACKGROUND

Dose painting (DP) aims to improve radiation therapy (RT) outcome by targeting radioresistant tumour regions identified through functional imaging, e.g., positron emission tomography (PET). Importantly, the expected benefit of DP relies on the ability of PET imaging to identify tumour areas which could be consistently targeted throughout the treatment. In this study, we analysed the spatial stability of two potential DP targets in lung cancer patients undergoing RT: the tumour burden surrogate [¹⁸F]fluorodeoxyglucose (FDG) and the hypoxia surrogate [¹⁸F]fluoroazomycin arabinoside (FAZA).

MATERIALS AND METHODS

Thirteen patients with unresectable lung tumours underwent FDG and FAZA 4D-PET/CT before (pre), and during the second (w2) and third (w3) weeks of RT. All PET/CT were reconstructed in their time-averaged midposition (MidP) for further analysis. The metabolic tumour volume (MTV: FDG standardised uptake value (SUV) > 50% SUV_max) and the hypoxic volume (HV: FAZA SUV >1.4) were delineated within the gross tumour volume (GTV_CT). The stability of FDG and FAZA PET uptake distributions during RT was subsequently assessed through volume-overlap analysis and voxel-based correlation analysis.

RESULTS

The volume-overlap analysis yielded median overlapping fraction (OF) of 0.86 between MTV_pre and MTV_w2 and 0.82 between MTV_pre and MTV_w3. In patients with a detectable HV, median OF was 0.82 between HV_pre and HV_w2 and 0.90 between HV_pre and HV_w3. The voxel-based correlation analysis yielded median Spearman's correlation coefficient (r_S) of 0.87 between FDG_pre and FDG_w2 and 0.83 between FDG_pre and FDG_w3. Median r_S was 0.78 between FAZA_pre and FAZA_w2 and 0.79 between FAZA_pre and FAZA_w3.

CONCLUSIONS

FDG and FAZA PET uptake distributions were spatially stable during the 3 first weeks of RT in patients with unresectable lung cancer, both based on volume- and voxel-based indicators. This might allow for a consistent targeting of high FDG or FAZA PET uptake regions as part of a DP strategy.

Predictive and Prognostic Value of Early Disease Progression by PET Evaluation in Advanced Non-Small Cell Lung Cancer

OBJECTIVE

To assess the predictive and prognostic value of progressive metabolic disease (PMD) by the use of early 18Fluorodeoxyglucose positron emission tomography (18FDG-PET) in patients with clinical stage IV non-small cell lung cancer (NSCLC) treated with first-line chemotherapy.

METHODS

An 18FDG-PET performed following the first cycle of chemotherapy (PET-1) was compared with a pretreatment 18FDG-PET (PET-0) and a computed tomography (CT) scan after the third cycle (CT-3). The primary endpoint was the positive predictive value (PPV) of PMD. Secondary endpoints included the prognostic value of PMD.

RESULTS

Eleven of 38 patients (29%) had a PMD by PET-1, and 15 (39%), including all patients with a PMD, experienced a progressive disease by CT-3. The PPV of PMD was 100% according to both the European Organization for Research and Treatment of Cancer (EORTC) criteria and the PET Response Criteria In Solid Tumors (PERCIST) (p value for both, <0.0001). Patients with a PMD by PET-1 had a median overall survival of 7.0 months versus 14.0 months for those without a PMD (p = 0.04, according to the EORTC criteria).

CONCLUSIONS

Early 18FDG-PET assessment deserves further investigation for the identification of NSCLC patients who do not benefit from first-line chemotherapy.

Applications and limitations of radiomics

Radiomics is an emerging field in quantitative imaging that uses advanced imaging features to objectively and quantitatively describe tumour phenotypes. Radiomic features have recently drawn considerable interest due to its potential predictive power for treatment outcomes and cancer genetics, which may have important applications in personalized medicine. In this technical review, we describe applications and challenges of the radiomic field. We will review radiomic application areas and technical issues, as well as proper practices for the designs of radiomic studies.

Regional Lymph Node Uptake of [(18)F]Fluorodeoxyglucose After Definitive Chemoradiation Therapy Predicts Local-Regional Failure of Locally Advanced Non-Small Cell Lung Cancer: Results of ACRIN 6668/RTOG 0235

PURPOSE

The American College of Radiology Imaging Network (ACRIN) 6668/Radiation Therapy Oncology Group (RTOG) 0235 study demonstrated that standardized uptake values (SUV) on post-treatment [(18)F]fluorodeoxyglucose-positron emission tomography (FDG-PET) correlated with survival in locally advanced non-small cell lung cancer (NSCLC). This secondary analysis determined whether SUV of regional lymph nodes (RLNs) on post-treatment FDG-PET correlated with patient outcomes.

METHODS AND MATERIALS

Included for analysis were patients treated with concurrent chemoradiation therapy, using radiation doses ≥60 Gy, with identifiable FDG-avid RLNs (distinct from primary tumor) on pretreatment FDG-PET, and post-treatment FDG-PET data. ACRIN core laboratory SUV measurements were used. Event time was calculated from the date of post-treatment FDG-PET. Local-regional failure was defined as failure within the treated RT volume and reported by the treating institution. Statistical analyses included Wilcoxon signed rank test, Kaplan-Meier curves (log rank test), and Cox proportional hazards regression modeling.

RESULTS

Of 234 trial-eligible patients, 139 (59%) had uptake in both primary tumor and RLNs on pretreatment FDG-PET and had SUV data from post-treatment FDG-PET. Maximum SUV was greater for primary tumor than for RLNs before treatment (P<.001) but not different post-treatment (P=.320). Post-treatment SUV of RLNs was not associated with overall survival. However, elevated post-treatment SUV of RLNs, both the absolute value and the percentage of residual activity compared to the pretreatment SUV were associated with inferior local-regional control (P<.001).

CONCLUSIONS

High residual metabolic activity in RLNs on post-treatment FDG-PET is associated with worse local-regional control. Based on these data, future trials evaluating a radiation therapy boost should consider inclusion of both primary tumor and FDG-avid RLNs in the boost volume to maximize local-regional control.

Outcomes of Modestly Hypofractionated Radiation for Lung Tumors: Pre- and Mid-Treatment Positron Emission Tomography-Computed Tomography Metrics as Prognostic Factors

Many patients with lung tumors have tumors too large for stereotactic ablative radiotherapy and comorbidities precluding concurrent chemotherapy. We report the outcomes of 29 patients treated with hypofractionated radiotherapy (RT) to 60 to 66 Gy in 3-Gy fractions. We also report an exploratory analysis of the prognostic value of the pre- and mid-RT positron emission tomography-computed tomography.

INTRODUCTION

Modestly hypofractionated radiation therapy (HypoRT; 60-66 Gy in 3-Gy fractions) allows patients with locally advanced thoracic tumors and poor performance status to complete treatment within a shorter period without concurrent chemotherapy. We evaluated the outcomes and imaging prognostic factors of HypoRT.

MATERIALS AND METHODS

We retrospectively reviewed the data from all patients with primary and metastatic intrathoracic tumors treated with HypoRT from 2006 to 2012. We analyzed the survival and toxicity outcomes, including overall survival (OS), progression-free survival (PFS), local recurrence (LR), and distant metastasis. We also evaluated the following tumor metrics in an exploratory analysis: gross tumor volume (GTV), maximum standardized uptake value (SUVMax), and metabolic tumor volume using a threshold of ≥ 50% of the SUVMax (MTV50%) or the maximum gradient of fluorine-18 fluorodeoxyglucose uptake (MTVEdge). We assessed the association of these metrics and their changes from before to mid-RT using positron emission tomography-computed tomography (PET-CT) with OS and PFS.

RESULTS

We identified 29 patients, all with pre-RT and 20 with mid-RT PET-CT scans. The median follow-up period was 15 months. The 2-year overall and non-small-cell lung cancer-only rate for OS, PFS, and LR, was 59% and 59%, 52% and 41%, and 27% and 32%, respectively. No grade ≥ 3 toxicities developed. The median decrease in GTV, SUVMax, and MTVEdge was 11%, 24%, and 18%, respectively. Inferior OS was associated with a larger pre-RT MTVEdge (P = .005) and pre-RT MTV50% (P = .007). Inferior PFS was associated with a larger mid-RT SUVMax (P = .003).

CONCLUSION

These findings add to the growing body of data demonstrating promising outcomes and limited toxicity with HypoRT. The pre- and mid-RT PET-CT metrics could be useful for prognostic stratification in future clinical trials.

Prediction of response by FDG PET early during concurrent chemoradiotherapy for locally advanced non-small cell lung cancer

Purpose

To evaluate the predictive value of the early response of ¹⁸F-flurodeoxyglucose positron emission tomography (FDG PET) during concurrent chemoradiotherapy (CCRT) for locally advanced non-small cell lung cancer (NSCLC).

Materials and Methods

FDG PET was performed before and during CCRT for 13 NSCLC patients. Maximum standardized uptake value (SUV_max), mean standardized uptake value (SUV_mean), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were measured and the changes were calculated. These early metabolic changes were compared with the standard tumor response by computed tomograms (CT) one month after CCRT.

Results

One month after the completion of CCRT, 9 patients had partial response (PR) of tumor and 4 patients had stable disease. The percent changes of SUV_max (%ΔSUV_max) were larger in responder group than in non-responder group (55.7% ± 15.6% vs. 23.1% ± 19.0%, p = 0.01). The percent changes of SUV_mean (%ΔSUV_mean) were also larger in responder group than in non-responder group (54.4% ± 15.9% vs. 22.3% ± 23.0%, p = 0.01). The percent changes of MTV (%ΔMTV) or TLG (%ΔTLG) had no correlation with the tumor response after treatment. All the 7 patients (100%) with %ΔSUV_max ≥ 50% had PR, but only 2 out of 6 patients (33%) with %ΔSUV_max < 50% had PR after CCRT (p = 0.009). Likewise, all the 6 patients (100%) with %ΔSUV_mean ≥ 50% had PR, but only 3 out of 7 patients (43%) with %ΔSUV_mean < 50% had PR after CCRT (p = 0.026).

Conclusion

The degree of metabolic changes measured by PET-CT during CCRT was predictive for NSCLC tumor response after CCRT.

Comparison of texture features derived from static and respiratory-gated PET images in non-small cell lung cancer

BACKGROUND

PET-based texture features have been used to quantify tumor heterogeneity due to their predictive power in treatment outcome. We investigated the sensitivity of texture features to tumor motion by comparing static (3D) and respiratory-gated (4D) PET imaging.

METHODS

Twenty-six patients (34 lesions) received 3D and 4D [18F]FDG-PET scans before the chemo-radiotherapy. The acquired 4D data were retrospectively binned into five breathing phases to create the 4D image sequence. Texture features, including Maximal correlation coefficient (MCC), Long run low gray (LRLG), Coarseness, Contrast, and Busyness, were computed within the physician-defined tumor volume. The relative difference (δ3D-4D) in each texture between the 3D- and 4D-PET imaging was calculated. Coefficient of variation (CV) was used to determine the variability in the textures between all 4D-PET phases. Correlations between tumor volume, motion amplitude, and δ3D-4D were also assessed.

RESULTS

4D-PET increased LRLG ( = 1%-2%, p < 0.02), Busyness ( = 7%-19%, p < 0.01), and decreased MCC ( = 1%-2%, p < 7.5 × 10(-3)), Coarseness ( = 5%-10%, p < 0.05) and Contrast ( = 4%-6%, p > 0.08) compared to 3D-PET. Nearly negligible variability was found between the 4D phase bins with CV < 5% for MCC, LRLG, and Coarseness. For Contrast and Busyness, moderate variability was found with CV = 9% and 10%, respectively. No strong correlation was found between the tumor volume and δ3D-4D for the texture features. Motion amplitude had moderate impact on δ for MCC and Busyness and no impact for LRLG, Coarseness, and Contrast.

CONCLUSIONS

Significant differences were found in MCC, LRLG, Coarseness, and Busyness between 3D and 4D PET imaging. The variability between phase bins for MCC, LRLG, and Coarseness was negligible, suggesting that similar quantification can be obtained from all phases. Texture features, blurred out by respiratory motion during 3D-PET acquisition, can be better resolved by 4D-PET imaging. 4D-PET textures may have better prognostic value as they are less susceptible to tumor motion.

Monitoring tumour response during chemo-radiotherapy: a parametric method using FDG-PET/CT images in patients with oesophageal cancer

Background

The objective of this study is to investigate the feasibility and the additional interest of a parametric imaging (PI) method to monitor the early tumour metabolic response in a prospective series of oesophageal cancer patients who underwent positron emission tomography with fluoro-2-deoxy-d-glucose (FDG-PET/CT) before and during curative-intent chemo-radiotherapy.

Methods

Fifty-seven patients with squamous cell carcinoma (SCC) of the oesophagus prospectively underwent FDG-PET/CT before chemo-radiotherapy (CRT) (PET₁) and at 21 ± 3 days after the beginning of CRT (PET₂). The outcome was assessed at 3 months and 1 year after the completion of CRT (clinical examination, CT scan or FDG-PET/CT, biopsy). For each patient, PET₁ and PET₂ were registered using CT images. The 2 PET image sets were subtracted, so the voxels with significant changes in FDG uptake were identified. A model-based analysis of this graph was used to identify the tumour voxels in which significant changes occurred between the two scans and yielded indices characterising these changes (green and red clusters). Quantitative parameters were compared with clinical outcome at 3 months and at 1 year.

Results

The baseline tumour FDG uptake decreased significantly at PET₂ (p < 0.0001). The tumour volume significantly decreased between PET₁ and PET₂ (p < 0.02). The initial functional volume of the lesion (TV₁) was significantly lower (p < 0.02) in patients in clinical response (CR) at 3 months and 1 year. The volume of the lesion during the treatment (TV₂) was significantly lower in patients identified as in CR at 3 months (p < 0.03), but did not predict the outcome at 1 year. Multivariate analyses of outcome at 3 months showed that the risk of failure/death increased with younger age (p = 0.001), larger metabolic volume on PET₁ (p = 0.009) and larger volume with decreased FDG uptake (p = 0.047). As for outcome at 1 year, the risk of failure/death increased with younger age (p = 0.006), nodal involvement (p = 0.08) and larger volumes with increased uptake (p = 0.03).

Conclusion

A parametric method to assess tumour response on serial FDG-PET performed during chemo-radiotherapy was evaluated. Early metabolic changes, i.e. variations in FDG uptake, provided additional prognostic information in multivariate analyses ClinicalTrials.gov NCT 00934505.

Trial registration

Current Controlled Trials ISRCTN7824458

FDG PET during radiochemotherapy is predictive of outcome at 1 year in non-small-cell lung cancer patients: a prospective multicentre study (RTEP2)

PURPOSE

To assess prospectively the prognostic value of FDG PET/CT during curative-intent radiotherapy (RT) with or without concomitant chemotherapy in patients with non-small-cell lung cancer (NSCLC).

METHODS

Patients with histological proof of invasive localized NSCLC and evaluable tumour, and who were candidates for curative-intent radiochemotherapy (RCT) or RT were preincluded after providing written informed consent. Definitive inclusion was conditional upon significant FDG uptake before RT (PET₁). All included patients had a FDG PET/CT scan during RT (PET₂, mean dose 43 Gy) and were evaluated by FDG PET/CT at 3 months and 1 year after RT. The main endpoint was death (from whatever cause) or tumour progression at 1 year.

RESULTS

Of 77 patients preincluded, 52 were evaluable. Among the evaluable patients, 77% received RT with induction chemotherapy and 73% RT with concomitant chemotherapy. At 1 year, 40 patients (77 %) had died or had tumour progression. No statistically significant association was found between stage (IIIB vs. other), histology (squamous cell carcinoma vs. other), induction or concomitant chemotherapy, and death/tumour progression at 1 year. The SUVmax in the PET2 scan was the single variable predictive of death or tumour progression at 1 year (odds ratio 1.97, 95% CI 1.25 - 3.09, p = 0.003) in multivariate analysis. The area under the receiver operating characteristic curve was 0.85 (95% CI 0.73 - 0.94, p < 10(-4)). A SUVmax value of 5.3 in the PET₂ scan yielded a sensitivity of 70% and a specificity of 92% for predicting tumour progression or death at 1 year.

CONCLUSION

This prospective multicentre study demonstrated the prognostic value in terms of disease-free survival of SUVmax assessed during the 5th week of curative-intent RT or RCT in NSCLC patients (NCT01261598; RTEP2 study).

Recent Trends in PET Image Interpretations Using Volumetric and Texture-based Quantification Methods in Nuclear Oncology

Image quantification studies in positron emission tomography/computed tomography (PET/CT) are of immense importance in the diagnosis and follow-up of variety of cancers. In this review we have described the current image quantification methodologies employed in (18)F-fluorodeoxyglucose ((18)F-FDG) PET in major oncological conditions with particular emphasis on tumor heterogeneity studies. We have described various quantitative parameters being used in PET image analysis. The main contemporary methodology is to measure tumor metabolic activity; however, analysis of other image-related parameters is also increasing. Primarily, we have identified the existing role of tumor heterogeneity studies in major cancers using (18)F-FDG PET. We have also described some newer radiopharmaceuticals other than (18)F-FDG being studied/used in the management of these cancers. Tumor heterogeneity studies are being performed in almost all major oncological conditions using (18)F-FDG PET. The role of these studies is very promising in the management of these conditions.

Are pretreatment 18F-FDG PET tumor textural features in non-small cell lung cancer associated with response and survival after chemoradiotherapy?

There is evidence in some solid tumors that textural features of tumoral uptake in (18)F-FDG PET images are associated with response to chemoradiotherapy and survival. We have investigated whether a similar relationship exists in non-small cell lung cancer (NSCLC).

METHODS

Fifty-three patients (mean age, 65.8 y; 31 men, 22 women) with NSCLC treated with chemoradiotherapy underwent pretreatment (18)F-FDG PET/CT scans. Response was assessed by CT Response Evaluation Criteria in Solid Tumors (RECIST) at 12 wk. Overall survival (OS), progression-free survival (PFS), and local PFS (LPFS) were recorded. Primary tumor texture was measured by the parameters coarseness, contrast, busyness, and complexity. The following parameters were also derived from the PET data: primary tumor standardized uptake values (SUVs) (mean SUV, maximum SUV, and peak SUV), metabolic tumor volume, and total lesion glycolysis.

RESULTS

Compared with nonresponders, RECIST responders showed lower coarseness (mean, 0.012 vs. 0.027; P = 0.004) and higher contrast (mean, 0.11 vs. 0.044; P = 0.002) and busyness (mean, 0.76 vs. 0.37; P = 0.027). Neither complexity nor any of the SUV parameters predicted RECIST response. By Kaplan-Meier analysis, OS, PFS, and LPFS were lower in patients with high primary tumor coarseness (median, 21.1 mo vs. not reached, P = 0.003; 12.6 vs. 25.8 mo, P = 0.002; and 12.9 vs. 20.5 mo, P = 0.016, respectively). Tumor coarseness was an independent predictor of OS on multivariable analysis. Contrast and busyness did not show significant associations with OS (P = 0.075 and 0.059, respectively), but PFS and LPFS were longer in patients with high levels of each (for contrast: median of 20.5 vs. 12.6 mo, P = 0.015, and median not reached vs. 24 mo, P = 0.02; and for busyness: median of 20.5 vs. 12.6 mo, P = 0.01, and median not reached vs. 24 mo, P = 0.006). Neither complexity nor any of the SUV parameters showed significant associations with the survival parameters.

CONCLUSION

In NSCLC, baseline (18)F-FDG PET scan uptake showing abnormal texture as measured by coarseness, contrast, and busyness is associated with nonresponse to chemoradiotherapy by RECIST and with poorer prognosis. Measurement of tumor metabolic heterogeneity with these parameters may provide indices that can be used to stratify patients in clinical trials for lung cancer chemoradiotherapy.

Response assessment using 18F-FDG PET early in the course of radiotherapy correlates with survival in advanced-stage non-small cell lung cancer

This study investigated the possibility of early response assessment based on (18)F-FDG uptake during radiotherapy with respect to overall survival in patients with non-small cell lung cancer.

METHODS

(18)F-FDG PET/CT was performed before radiotherapy and was repeated in the second week of radiotherapy for 34 consecutive lung cancer patients. The CT volume and standardized uptake value (SUV) parameters of the primary tumor were quantified at both time points. Changes in volume and SUV parameters correlated with 2-y overall survival.

RESULTS

The average change in mean SUV in the primary tumor of patients with a 2-y survival was a decrease by 20% ± 21%-significantly different (P < 0.007) from nonsurvivors, who had an increase by 2% ± 22%. A sensitivity and specificity of 63% and 93%, respectively, to separate the 2 groups was reached for a decrease in mean SUV of 15%. Survival curves were significantly different using this cutoff (P = 0.001). The hazard ratio for a 1% decrease in mean SUV was 1.032 (95% confidence interval, 1.010-1.055). Changes in tumor volume defined on CT did not correlate with overall survival.

CONCLUSION

The use of repeated (18)F-FDG PET to assess treatment response early during radiotherapy is possible in patients undergoing radiotherapy or sequential or concurrent chemoradiotherapy. A decrease in (18)F-FDG uptake by the primary tumor correlates with higher long-term overall survival.

The clinical significance and management of lesion motion due to respiration during PET/CT scanning

Lesion movement during positron emission tomography (PET) scan acquisition due to normal respiration is a common source of artefact. A PET scan is acquired in multiple couch positions of between 2 and 5 min duration with the patient breathing freely. A PET-avid lesion will become blurred if affected by respiratory motion, an effect similar to that created when a person moves in a photograph. This motion also frequently causes misregistration between the PET and computed tomography (CT) scan acquired for attenuation correction and anatomical correlation on hybrid scanners. The compounding effects of blurring and misregistration in whole-body PET/CT imaging make accurate characterization of PET-avid disease in areas of high respiratory motion challenging. There is also increasing interest in using PET quantitatively to assess disease response in both clinical reporting and trials. However, at this stage, no response criteria take the effect of respiratory motion into account when calculating the standardized uptake value on a PET scan. A number of different approaches have been described in the literature to address the issue of respiratory motion in PET/CT scanning. This review details the clinical significance of lesion movement due to respiration and discusses various imaging techniques that have been investigated to manage the effects of respiratory motion in PET/CT scanning.

Role of positron emission tomography in the early prediction of response to chemotherapy in patients with non--small-cell lung cancer

In recent years, molecular imaging with [(18)F]fluorodeoxyglucose-positron-emission tomography, [(18)F]FDG-PET, has become part of the standard of care in initial staging of patients with non-small-cell lung cancer. Currently, there is an increasing interest in the role of [(18)F]FDG-PET in the evaluation of biological characteristics of the tumor and the prediction of response to anticancer therapies at an early phase of treatment. According to the existing data, quantitative assessment of therapy-induced changes in tumor [(18)F]FDG uptake may allow the prediction of tumor response and patient outcome very early in the course of therapy. Treatment may be adjusted according to the chemosensitivity of the tumor tissue in an individual patient. Thus, [(18)F]FDG-PET has the potential to reduce the side effects and costs of ineffective therapy. This review provides an update on recent studies that evaluate the role of [(18)F]FDG-PET in the early prediction of response to chemotherapy and prognosis in patients with non-small-cell lung cancer. In addition, it discusses the application of [(18)F]FDG-PET to the monitoring of new targeted forms of anticancer therapy and particularly of epidermal growth factor receptor tyrosine kinase inhibitors. Finally, it evaluates the usefulness of [(18)F]fluorothymidine, a PET tracer for imaging tumor proliferation, in predicting response to therapy in patients with lung cancer.