Is FDG-PET suitable for evaluating neoadjuvant therapy in non-small cell lung cancer? Evidence with systematic review of the literature

Utility of 18F-FDG PET/CT uptake values in predicting response to neoadjuvant chemoimmunotherapy in resectable non-small cell lung cancer

INTRODUCTION

Reliable predictive markers are lacking for resectable non-small cell lung cancer (NSCLC) patients treated with neoadjuvant chemoimmunotherapy. The present study investigated the utility of SUV_max values acquired from PET/CT to predict the response to neoadjuvant chemoimmunotherapy for resectable NSCLC.

MATERAL AND METHODS

SUV_max, clinical and pathological outcomes, were collected from patients in 5 hospitals. Patients who received dynamic PET/CT surveillance were divided into cohorts A (chemoimmunotherapy) and B (chemotherapy), respectively, while cohort C (chemoimmunotherapy) comprised patients undergoing post-therapy PET/CT. Associations between SUV_max and major pathologic response (MPR) were evaluated through receiver operating characteristic (ROC) curves.

RESULTS

A total of 129 cases with an MPR rate of 46.5 % was identified. In neoadjuvant chemoimmunotherapy, ΔSUV_max% (AUC: 0.890, 95 % CI: 0.761-0.949) and post-therapy SUV_max (AUC: 0.933, 95 % CI: 0.802-0.959) could accurately predict MPR. On the contrary, the baseline SUV_max was not associated with MPR (p = 0.184). Furthermore, an independent cohort C proved that post-therapy SUV_max could serve as an independent predictor (AUC: 0.928, 95 % CI: 0.823-0.958). In addition, robust predictive performance could be observed when we use the optimal cut-off point of both ΔSUV_max% (54.4 %, AUC: 0.912, 95 % CI: 0.824-0.994) and post-therapy SUV_max (3.565, AUC: 0.912, 95 % CI: 0.824-0.994) in neoadjuvant chemoimmunotherapy. The RNA data revealed that the expression of PFKFB4, a key enzyme in glycolysis, was positively correlated with SUV_max value and tumor cell proliferation after neoadjuvant chemoimmunotherapy.

CONCLUSION

These findings highlighted that the ΔSUV_max% and remained SUV_max were accurate and non-invasive tests for the prediction of MPR after neoadjuvant chemoimmunotherapy.

Test-Retest Variability in Lesion SUV and Lesion SUR in 18F-FDG PET: An Analysis of Data from Two Prospective Multicenter Trials

Quantitative assessment of radio- and chemotherapy response with ¹⁸F-FDG whole-body PET has attracted increasing interest in recent years. In most published work, SUV has been used for this purpose. In the context of therapy response assessment, the reliability of lesion SUVs, notably their test-retest stability, thus becomes crucial. However, a recent study demonstrated substantial test-retest variability (TRV) in SUVs. The purpose of the present study was to investigate whether the tumor-to-blood SUV ratio (SUR) can improve TRV in tracer uptake. Methods: 73 patients with advanced non-small cell lung cancer from the prospective multicenter trials ACRIN 6678 (n = 34) and MK-0646-008 (n = 39) were included in this study. All patients underwent two ¹⁸F-FDG PET/CT investigations on two different days (time difference, 3.6 ± 2.1 d; range, 1-7 d) before therapy. For each patient, up to 7 tumor lesions were evaluated. For each lesion, SUV_max and SUV_peak were determined. Blood SUV was determined as the mean value of a 3-dimensional aortic region of interest that was delineated on the attenuation CT image and transferred to the PET image. SURs were computed as the ratio of tumor SUV to blood SUV and were uptake time-corrected to 75 min after injection. TRV was quantified as 1.96 multiplied by the root-mean-square deviation of the fractional paired differences in SUV and SUR. The combined effect of blood normalization and uptake time correction was inspected by considering R_TRV (TRV_SUR/TRV_SUV), a ratio reflecting the reduction in the TRV in SUR relative to SUV. R_TRV was correlated with the group-averaged-value difference (δ) in CF_mean (δCF_mean) of the quantity δCF = |CF - 1|, where CF is the numeric factor that converts individual ratios of paired SUVs into corresponding SURs. This correlation analysis was performed by successively increasing a threshold value δCF_min and computing δCF_mean and R_TRV for the remaining subgroup of patients/lesions with δCF ≥ δCF_minResults: The group-averaged TRV_SUV and TRV_SUR were 32.1 and 29.0, respectively, which correspond to a reduction of variability in SUR by an R_TRV factor of 0.9 in comparison to SUV. This rather marginal improvement can be understood to be a consequence of the atypically low intrasubject variability in blood SUV and uptake time and the accordingly small δCF values in the investigated prospective study groups. In fact, subgroup analysis with increasing δCF_min thresholds revealed a pronounced negative correlation (Spearman ρ = -0.99, P < 0.001) between R_TRV and δCF_mean, where R_TRV ≈ 0.4 in the δCF_min = 20% subgroup, corresponding to a more than 2-fold reduction of TRV_SUR compared with TRV_SUVConclusion: Variability in blood SUV and uptake time has been identified as a causal factor in the TRV in lesion SUV. Therefore, TRV in lesion uptake measurements can be reduced by replacing SUV with SUR as the uptake measure. The improvement becomes substantial for the level of variability in blood SUV and uptake time typically observed in the clinical context.

Prognostic factors in non-small cell lung cancer patients who received neoadjuvant therapy and curative resection

BACKGROUND

Lung cancer is the leading cause of cancer deaths in the world, and more and more treatment modalities have been introduced in order to improve patients' survival. For patients with advanced non-small cell lung cancer (NSCLC), survival prognosis is poor and multimodality neoadjuvant therapies are given to improve patients' survival. However, the possibility of occult metastases may lead to discrepancy between clinical and pathologic staging and underestimation of the disease severity. This discrepancy could be the reason for poor survival prediction reported by previous studies which conducted their analysis from the point of view of clinical stage. The aim of this study was to analyze the relationship between clinico-pathologic factors and survival from the pathologic point of view and to try to identify survival prognostic factors.

METHODS

From January 2005 to June 2011, 88 patients received neoadjuvant therapy because of initial locally advanced disease, followed by anatomic resection and mediastinal lymph node (LN) dissection. All their clinico-pathologic data were collected from a retrospective review of the medical records and subjected to further analysis.

RESULTS

We found that total metastatic LN ratio (P=0.01) and tumor size (P=0.02) were predictive factors for disease free survival (DFS). We used these two prognostic factors to stratify all patients into four groups. Group 4 (tumor size ≤5, total metastatic LN ratio ≤0.065) had the best DFS curve, while the DFS curve progressively deteriorated across group 3 (tumor size ≤5, total metastatic LN ratio >0.065), group 2 (tumor size >5, total metastatic LN ratio ≤0.065) and group 1 (tumor size >5, total metastatic LN ratio >0.065). However, no definitive prognostic factor could be identified in this study.

CONCLUSIONS

In conclusion, tumor size greater than 5 cm and total metastatic LN ratio greater than 0.065 could predict the DFS of patients with advanced NSCLC after multimodality therapies followed by surgical resection. Tumor size plays a more important role than total metastatic LN ratio in DFS. Moreover, patients identified with these factors need active post-operation surveillance and additional aggressive adjuvant therapies.

Mechanism and non-mechanism based imaging biomarkers for assessing biological response to treatment in non-small cell lung cancer

Therapeutic options in locally advanced non-small cell lung cancer (NSCLC) have expanded in the past decade to include a palate of targeted interventions such as high dose targeted thermal ablations, radiotherapy and growing platform of antibody and small molecule therapies and immunotherapies. Although these therapies have varied mechanisms of action, they often induce changes in tumour architecture and microenvironment such that response is not always accompanied by early reduction in tumour mass, and evaluation by criteria other than size is needed to report more effectively on response. Functional imaging techniques, which probe the tumour and its microenvironment through novel positron emission tomography and magnetic resonance imaging techniques, offer more detailed insights into and quantitation of tumour response than is available on anatomical imaging alone. Use of these biomarkers, or other rational combinations as readouts of pathological response in NSCLC have potential to provide more accurate predictors of treatment outcomes. In this article, the robustness of the more commonly available positron emission tomography and magnetic resonance imaging biomarker indices is examined and the evidence for their application in NSCLC is reviewed.

Postinduction positron emission tomography assessment of N2 nodes is not associated with ypN2 disease or overall survival in stage IIIA non-small cell lung cancer

OBJECTIVE

Induction therapy is often recommended for patients with clinical stage IIIA-N2 (cIIIA/pN2) lung cancer. We examined whether postinduction positron emission tomography (PET) scans were associated with ypN2 disease and survival of patients with cIIIA/pN2 disease.

METHODS

We performed a retrospective review of a prospectively maintained database to identify patients with cIIIA/pN2 non-small cell lung cancer treated with induction chemotherapy followed by surgery between January 2007 and December 2012. The primary aim was the association between postinduction PET avidity and ypN2 status; the secondary aims were overall survival, disease-free survival, and recurrence.

RESULTS

Persistent pathologic N2 disease was present in 61% of patients (61 out of 100). PET N2-negative disease increased from 7% (6 out of 92) before induction therapy to 47% (36 out of 77) afterward. The sensitivity, specificity, and accuracy of postinduction PET for identification of ypN2 disease were 59%, 55%, and 57%, respectively. Logistic regression analysis indicated that postinduction PET N2 status was not associated with ypN2 disease. Of the 39 patients with both pre- and postinduction PET N2-avidity, 25 (64%) had ypN2 disease. The 5-year overall survival was 40% for ypN2 disease versus 38% for N2-persistent disease (P = .936); the 5-year overall survival was 43% for postinduction PET N2-negative disease versus 39% for N2-avid disease (P = .251). The 5-year disease-free survival was 34% for ypN2-negative disease versus 9% for N2-persistent disease (P = .079).

CONCLUSIONS

Postinduction PET avidity for N2 nodes is not associated with ypN2 disease, overall survival, or disease-free survival in patients undergoing induction chemotherapy for stage IIIA/pN2 disease.

Current methods of staging and restaging of the mediastinal nodes in non-small-cell lung cancer

To analyze the current methods of primary staging and repeated staging (restaging) of the mediastinal nodes in non-small-cell lung cancer (NSCLC), all methods currently used for staging of NSCLC are analyzed. These methods include imaging techniques [computer tomography (CT), positron emission tomography (PET) combined with CT (PET/CT)], endoscopic/ultrasound techniques (endobronchial ultrasound/transbronchial needle aspiration) and endoscopic ultrasound/fine needle aspiration and surgical techniques [standard cervical mediastinoscopy, video-assisted mediastinoscopy, extended mediastinoscopy, video-assisted mediastinoscopic lymphadenectomy, transcervical extended mediastinal lymphadenectomy, anterior mediastinotomy (Chamberlain procedure) and video-assisted thoracic surgery]. The diagnostic yield of Chest CT is regarded insufficient for both, primary staging and restaging. The PET/CT became a standard imaging technique preceding curative surgery of radical chemo-radiotherapy. The issue of intraoperative staging is also described. Finally, the author’s proposed algorithm of staging, both for primary staging and restaging after neoadjuvant therapy is presented. Detailed staging of NSCLC enables selection of patients with early stage disease for curative surgical/multimodality treatment and helps to avoid unnecessary surgery in advanced disease.

The role of PET-CT in radiotherapy planning of solid tumours

Background

PET-CT is becoming more and more important in various aspects of oncology. Until recently it was used mainly as part of diagnostic procedures and for evaluation of treatment results. With development of personalized radiotherapy, volumetric and radiobiological characteristics of individual tumour have become integrated in the multistep radiotherapy (RT) planning process. Standard anatomical imaging used to select and delineate RT target volumes can be enriched by the information on tumour biology gained by PET-CT. In this review we explore the current and possible future role of PET-CT in radiotherapy treatment planning. After general explanation, we assess its role in radiotherapy of those solid tumours for which PET-CT is being used most.

Conclusions

In the nearby future PET-CT will be an integral part of the most radiotherapy treatment planning procedures in an every-day clinical practice. Apart from a clear role in radiation planning of lung cancer, with forthcoming clinical trials, we will get more evidence of the optimal use of PET-CT in radiotherapy planning of other solid tumours.

The Latest in Surgical Management of Stage IIIA Non-Small Cell Lung Cancer: Video-Assisted Thoracic Surgery and Tumor Molecular Profiling

Stage IIIA non-small cell lung cancer (NSCLC) remains a treatment challenge and requires a multidisciplinary care team to optimize survival outcomes. Thoracic surgeons play an important role in selecting operative candidates and assisting with pathologic mediastinal staging via cervical mediastinoscopy, endobronchial ultrasound, or esophageal ultrasound with fine needle aspiration. The majority of patients with stage IIIA disease will receive induction therapy followed by repeat staging before undergoing lobectomy or pneumonectomy; occasionally, a patient with an incidentally found, single-station microscopic IIIA tumor will undergo resection as the primary initial therapy. Multiple large clinical trials, including SWOG-8805, EORTC-8941, INT-0139, and ANITA, have shown 5-year overall survival rates of up to 30% to 40% using triple-modality treatments, and the best outcomes repeatedly are seen among patients who respond to induction treatment or who have tumors amenable to lobectomy instead of pneumonectomy. The need for a pneumonectomy is not a reason to deny patients an operation, because current operative mortality and morbidity rates are acceptably low at 5% and 30%, respectively. In select patients with stage IIIA disease, video-assisted thoracic surgery and open resections have been shown to have comparable rates of local recurrence and long-term survival. New developments in genetic profiling and personalized medicine are exciting areas of research, and early data suggest that molecular profiling of stage IIIA NSCLC tumors can accurately stratify patients by risk within this stage and predict survival outcomes. Future advances in treating stage IIIA disease will involve developing better systemic therapies and customizing treatment plans on the basis of an individual tumor's genetic profile.

PET/CT in therapy evaluation of patients with lung cancer

FDG-PET/CT is a well documented and widespread used imaging modality for the diagnosis and staging of patient with lung cancer. FDG-PET/CT is increasingly used for the assessment of treatment effects during and after chemotherapy. However, PET is not an accepted surrogate end-point for assessment of response rate in clinical trials. The aim of this review is to present current evidence on the use of PET in response evaluation of patients with lung cancer and to introduce the pearls and pitfalls of the PET-technology relating to response assessment. Based on this and relating to validation criteria, including stable technology, standardization, reproducibility and broad availability, the review discusses why, despite numerous studies on response assessment indicating a possible role for FDG-PET/CT, PET still has no place in guidelines relating to response evaluation in lung cancer.

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.

18F-FDG-PET evaluation of pathological tumour response to neoadjuvant therapy in patients with NSCLC

OBJECTIVES

The ability to identify potential responders to neoadjuvant treatment may improve patient selection or surgery and may help in the development of response criteria suitable for routine monitoring of response. The aim of this study was to evaluate the value of PET in predicting the pathological tumour response of non-small-cell lung cancer (NSCLC) to neoadjuvant therapy using a meta-analysis.

METHODS

All available published studies investigating the value of PET in predicting the pathological response of NSCLC to neoadjuvant therapy were collected. Pooled sensitivity and specificity data were obtained using statistical software. Subgroup analysis was performed to explore the sources of heterogeneity.

RESULTS

A total of 13 studies comprising 414 patients with NSCLC were included in the meta-analysis. Pooled sensitivity, specificity, positive predictive value and negative predictive value for PET-predicted response was 83% [95% confidence interval (CI); 76-89%], 84% (95% CI; 79-88%), 74% (95% CI; 67-81%) and 91% (95% CI; 87-94%), respectively. Significant heterogeneity (P<0.05) was observed. On the basis of our subgroup analyses, methodological quality could be responsible for this heterogeneity in our metaregression. The predictive value of PET in NSCLC patients with pathological response (considered the gold standard) was significantly higher than that of computed tomography (P<0.05).

CONCLUSION

PET scanning has an important role in predicting nonresponders to neoadjuvant therapy in cases of NSCLC, and the predictive value of PET for evaluating pathologically documented responses is superior to that of computed tomography. However, additional evaluations using prospective clinical trials will be required to assess the clinical benefit of this strategy.

Role of induction therapy: surgical resection of non-small cell lung cancer after induction therapy

Patients with Stage III non-small cell lung cancer are best managed by multimodality therapy. Patients with N2 disease can be treated with induction therapy (usually chemotherapy) followed by surgical resection. Patients whose medical comorbidities preclude surgery should be treated with definitive chemoradiotherapy. T3 or T4 tumors involving the superior sulcus or spine are best managed with induction chemoradiotherapy and surgical resection.

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.

The use and misuse of positron emission tomography in lung cancer evaluation

This article discusses the potential benefits and limitations of positron emission tomography (PET) for characterizing lung nodules, staging the mediastinum, identifying occult distant metastasis, determining prognosis and treatment response, guiding plans for radiation therapy, restaging during and after treatment, and selecting targets for tissue sampling. The key findings from the medical literature are presented regarding the capabilities and fallibilities of PET in lung cancer evaluation, including characterization of pulmonary nodules and staging in patients with known or suspected non-small-cell lung cancer. The discussion is limited to PET imaging with fluorodeoxyglucose.

Mediastinal re-staging of non small-cell lung cancer

Selected patients with non small-cell lung cancer (NSCLC) with mediastinal lymph node involvement may have a survival benefit from surgical resection, particularly if mediastinal nodal down-staging occurs after induction therapy and complete resection is achieved with lobectomy. Accurate re-staging of the mediastinum after induction therapy is therefore crucial in determining prognosis and subsequent treatment. Non-invasive imaging techniques usually require a confirmatory tissue sampling method to improve the accuracy of mediastinal re-staging. As in the initial staging of the mediastinum, minimally invasive endosonography-guided needle sampling techniques such as endobronchial ultrasound-guided fine-needle aspiration (EBUS-TBNA) and endoscopic ultrasound-guided fine-needle aspiration show promise in re-staging the mediastinum, though invasive surgical re-staging remains the gold standard. Despite a lower sensitivity in the mediastinal re-staging of NSCLC, EBUS-TBNA with or without EUS-FNA may still be the preferred initial mediastinal re-staging technique.

[Role of FDG-PET scanning in stage IIIAN2 non-small cell lung cancer]

Patients with clinical stage IIIAN2 non-small cell lung cancer (NSCLC) are a heterogeneous subgroup in term of prognosis and therapeutic management. The optimal management of this patient group is a major focus for thoracic oncology research and the concept of multimodality treatment has recently been introduced. This approach combines induction chemotherapy or radiochemotherapy followed by surgery in the case of mediastinal lymph node down-staging. positron emission tomography computed tomography with [18F]-fluorodesoxyglucose (FDG-PET) is a molecular and metabolic imaging modality which combines the metabolic data of PET with morphological data from CT. FDG-PET has become a standard in lung cancer management since the different indications listed in the standards, options and recommendations (SOR) of the FNCLCC. However, the potential specific importance of FDG-PET in IIIAN2 patients needs to be addressed further. In this setting, the authors' objective is to review the potential role of metabolic imaging in stage IIIAN2 NSCLC, taking into account new multimodality treatments. In stage IIIAN2, FDG-PET has performed better than morphoradiological imaging for baseline and postinduction lymph node staging, the identification of distant metastasis, and determining prognosis, as well as assessing the response to treatment.

Integrated PET/CT in non small cell lung cancer staging--clinical and pathological agreement

INTRODUCTION

Integrated PET/CT has become a fundamental tool in the preoperative assessment of non small lung cancer (NSCLC) providing useful anatomical and metabolic information to characterize tumoral lesions and to detect unsuspected metastatic disease.

AIM

To compare the agreement between clinical and pathological staging before and after the use of PET/CT.

MATERIAL AND METHODS

Retrospective study of patients with NSCLC who underwent potentially curative surgery throughout 10.5 years. Cohen's kappa coefficient was used to evaluate staging agreement.

RESULTS

One hundred and fifty patients were evaluated, 78% males, with a mean age of 65 (±9.6) years. Thirteen percent were submitted to neoadjuvant chemotherapy. PET/CT was performed in 41%. Global agreement between clinical and pathological staging was 51% (kappa=0.3639). There was a statistically significant difference between the staging results in patients who underwent PET/CT, when compared to the subgroup who did not (p=0.003). For those with PET/CT false negatives occurred in less 39%, false positives in more 12% and clinical and pathological staging coincided in more 27%. The overall results reflected an improvement in the agreement between clinical and pathological staging in the PET/CT subgroup (67%, kappa=0.5737 vs 40%, kappa=0.2292). PET/CT accuracy was enhanced when patients re-staged after neoadjuvant therapy were excluded and a substantial staging agreement was obtained for those who had the exam only for staging purposes (73%, kappa=0.6323).

CONCLUSION

Inclusion of PET/CT in NSCLC preoperative assessment improved the accuracy of the clinical staging, with a good level of agreement with pathological staging.

Functional imaging in predicting response to antineoplastic agents and molecular targeted therapies in lung cancer: a review of existing evidence

The increasing use of FDG-PET ((18)F-2-fluoro-2-deoxy-d-glucose positron emission tomography) imaging in the staging of non-small-cell lung cancer (NSCLC) may result in a significant shift in stage distribution, with an increased percentage of patients staged as having metastatic disease and consequently a higher percentage of patients treated with systemic therapy. The amount of FDG-PET uptake in primary lung lesions has been shown to be correlated with tumour growth rate. Data suggest that tumours with increased glucose uptake are presumably more metabolically active and more biologically aggressive, and standardized uptake value (SUV) at PET may be regarded as a prognostic factor. Growing evidence suggests that PET may be used as a predictive marker to assess the activity of antineoplastic agents, allowing close monitoring of the efficacy of the treatment in order to be able to switch earlier to alternative therapies according to the individual chemosensitivity of the tumour. Currently the value of FDG-PET for monitoring response is complicated by the heterogeneity of the published data on the methods used for FDG quantification and the selection of the primary targets and clinical endpoints. As a result, objective validation of proposed thresholds of responsiveness is lacking. This article discusses the assessment of treatment response in NSCLC patients using functional imaging, and emphasizes advantages and limitations in clinical management.

[New endoscopic ultrasound (EUS) applications in lung cancer: evaluation of patients with negative mediastinal CT and re-staging after neoadjuvant treatment]

The main purpose of staging in non-small cell lung cancer (NSCLC) is to assess mediastinal lymph node involvement, with thoracic CT being the main non-invasive test for this. However, given that up to 15% of patients who show no mediastinal lymph node involvement in the CT have lymph node metastasis during surgery, other examinations are required. Endoscopic ultrasonography guided fine-needle aspiration (EUS-FNA) has shown to be able to detect advanced disease (metastatic mediastinal lymph nodes, adrenal metastasis, mediastinal invasion by the tumour) in approximately 25% of patients with a CT that suggested a non-advanced disease. Another situation in which CT has a very limited value is in the evaluation of the response to induction therapy, with its most limiting factor being its intrinsic inability to distinguish between a tumour and necrosis. In this context, EUS-FNA has shown to have a good performance, with a sensitivity, negative predictive value and precision of 75%, 67% and 83%, respectively. In conclusion, EUS-FNA may be considered a good alternative in the pre-operative staging of patients with NSCLC, with and without diseased mediastinal lymph nodes in CT, and could play an important role in the mediastinal re-staging of these patients by identifying a patient sub-group who might benefit from additional surgical treatment.