Therapeutic implications of molecular imaging with PET in the combined modality treatment of lung cancer

Development and validation of a prognostic nomogram model in locally advanced NSCLC based on metabolic features of PET/CT and hematological inflammatory indicators

BACKGROUND

We combined the metabolic features of 18F-FDG-PET/CT and hematological inflammatory indicators to establish a predictive model of the outcomes of patients with locally advanced non-small cell lung cancer (LA-NSCLC) receiving concurrent chemoradiotherapy.

RESULTS

A predictive nomogram was developed based on sex, CEA, systemic immune-inflammation index (SII), mean SUV (SUVmean), and total lesion glycolysis (TLG). The nomogram presents nice discrimination that yielded an AUC of 0.76 (95% confidence interval: 0.66-0.86) to predict 1-year PFS, with a sensitivity of 63.6%, a specificity of 83.3%, a positive predictive value of 83.7%, and a negative predictive value of 62.9% in the training set. The calibration curves and DCA suggested that the nomogram had good calibration and fit, as well as promising clinical effectiveness in the training set. In addition, survival analysis indicated that patients in the low-risk group had a significantly longer mPFS than those in the high-risk group (16.8 months versus 8.4 months, P < 0.001). Those results were supported by the results in the internal and external test sets.

CONCLUSIONS

The newly constructed predictive nomogram model presented promising discrimination, calibration, and clinical applicability and can be used as an individualized prognostic tool to facilitate precision treatment in clinical practice.

Potential role of pre-treatment bone marrow SUVmean to liver SUVmean ratio (BM/L) and comparison of primary tumour FDG uptake with brain FDG uptake in predicting survival in limited-stage lung cancers

INTRODUCTION

The survival rates of patients with limited-stage small-cell lung cancer are low despite curative treatment. Accordingly, we investigated the disease prognosis by comparing the pre-treatment bone marrow mean standardised uptake values (SUVmean) / liver SUVmean ratio (BM/L) and primary tumour FDG uptake and brain FDG uptake to prognosis.

MATERIALS AND METHODS

This was an observational, retrospective, single-centre study of patients with limited-stage small-cell lung cancer. Maximum standardised uptake values before treatment SUVmax, mean SUV (SUVmean), metabolic tumor volume (MTV), total lesion glycolysis (TLG), liver (KC) SUVmean, bone marrow SUVmean, BM/L ratio (grouped as BM/L <1 and BM/L<1), FDG uptake level of the primary tumour are higher than brain FDG uptake. The association of low prevalence with overall survival (OS) and progression-free survival (PFS) was evaluated.

DISCUSSION

A total of 125 patients were included in the study. The risk of death was found to be two times higher in patients with primary tumour FDG uptake higher than brain FDG uptake compared to those with less brain involvement. The risk of death in patients with BM/L>1 was found to be 1.6 times higher than in patients with BM/L<1.

CONCLUSION

Comparison of BM/L, FDG uptake of the primary tumour and brain FDG uptake as new prognostic parameters can be guiding in the classification of patients with LD-SCLC with a higher risk of death or progression and in planning new treatment strategies.

GOECP/SEOR radiotherapy guidelines for small-cell lung cancer

Small cell lung cancer (SCLC) accounts for approximately 20% of all lung cancers. The main treatment is chemotherapy (Ch). However, the addition of radiotherapy significantly improves overall survival (OS) in patients with non-metastatic SCLC and in those with metastatic SCLC who respond to Ch. Prophylactic cranial irradiation reduces the risk of brain metastases and improves OS in both metastatic and non-metastatic patients. The 5-year OS rate in patients with limited-stage disease (non-metastatic) is slightly higher than 30%, but less than 5% in patients with extensive-stage disease (metastatic). The present clinical guidelines were developed by Spanish radiation oncologists on behalf of the Oncologic Group for the Study of Lung Cancer/Spanish Society of Radiation Oncology to provide a current review of the diagnosis, planning, and treatment of SCLC. These guidelines emphasise treatment fields, radiation techniques, fractionation, concomitant treatment, and the optimal timing of Ch and radiotherapy. Finally, we discuss the main indications for reirradiation in local recurrence.

Prognostic Value of 18F-FDG-PET Parameters in Patients with Small Cell Lung Cancer: A Meta-Analysis and Review of Current Literature

Many studies have suggested a prognostic value of one or several positron emission tomography (PET) parameters in patients with small cell lung cancer (SCLC). However, studies are often small, and there is a considerable interstudy disagreement about which PET parameters have a prognostic value. The objective of this study was to perform a review and meta-analysis to identify the most promising PET parameter for prognostication. PubMed^®, Cochrane, and Embase^® were searched for papers addressing the prognostic value of any PET parameter at any treatment phase with any endpoint in patients with SCLC. Pooled hazard ratios (HRs) were calculated by a random effects model for the prognostic value of the baseline maximum standardized uptake value (SUV_max) and metabolic tumor volume (MTV). The qualitative analysis included 38 studies, of these, 19 studies were included in the meta-analyses. The pooled results showed that high baseline MTV was prognostic for overall survival (OS) (HR: 2.83 (95% confidence interval [CI]: 2.00–4.01) and progression-free survival (PFS) (HR: 3.11 (95% CI: 1.99–4.90)). The prognostic value of SUV_max was less pronounced (OS: HR: 1.50 (95% CI: 1.17–1.91); PFS: HR: 1.24 (95% CI: 0.94–1.63)). Baseline MTV is a strong prognosticator for OS and PFS in patients with SCLC. MTV has a prognostic value superior to those of other PET parameters, but whether MTV is superior to other prognosticators of tumor burden needs further investigation.

18F-Fluorodeoxyglucose PET in Locally Advanced Non-small Cell Lung Cancer: From Predicting Outcomes to Guiding Therapy

PET using 18-fluorodeoxyglucose (FDG) has become an important part of the work-up for non-small cell lung cancer (NSCLC). This article summarizes advancements in using FDG-PET for patients with locally advanced NSCLC treated with definitive radiation therapy (RT). This article discusses prognostication of outcome based on pretreatment or midtreatment PET metrics, using textural image features to predict treatment outcomes, and using PET to define RT target volumes and inform RT dose modifications. The role of PET is evolving and is moving toward using quantitative image information, with the overarching goal of individualizing therapy to improve outcomes for patients with NSCLC.

18F-fluorothymidine (FLT)-PET and diffusion-weighted MRI for early response evaluation in patients with small cell lung cancer: a pilot study

Background

Small cell lung cancer (SCLC) is an aggressive cancer often presenting in an advanced stage and prognosis is poor. Early response evaluation may have impact on the treatment strategy.

Aim

We evaluated ¹⁸F-fluorothymidine-(FLT)-PET/diffusion-weighted-(DW)-MRI early after treatment start to describe biological changes during therapy, the potential of early response evaluation, and the added value of FLT-PET/DW-MRI.

Methods

Patients with SCLC referred for standard chemotherapy were eligible. FLT-PET/DW-MRI of the chest and brain was acquired within 14 days after treatment start. FLT-PET/DW-MRI was compared with pretreatment FDG-PET/CT. Standardized uptake value (SUV), apparent diffusion coefficient (ADC), and functional tumor volumes were measured. FDG-SUV_peak, FLT-SUV_peak, and ADC_median; spatial distribution of aggressive areas; and voxel-by-voxel analyses were evaluated to compare the biological information derived from the three functional imaging modalities. FDG-SUV_peak, FLT-SUV_peak, and ADC_median were also analyzed for ability to predict final treatment response.

Results

Twelve patients with SCLC completed FLT-PET/MRI 1–9 days after treatment start. In nine patients, pretreatment FDG-PET/CT was available for comparison. A total of 16 T-sites and 12 N-sites were identified. No brain metastases were detected. FDG-SUV_peak was 2.0–22.7 in T-sites and 5.5–17.3 in N-sites. FLT-SUV_peak was 0.6–11.5 in T-sites and 1.2–2.4 in N-sites. ADC_median was 0.76–1.74 × 10^− 3 mm²/s in T-sites and 0.88–2.09 × 10⁻³ mm²/s in N-sites. FLT-SUV_peak correlated with FDG-SUV_peak, and voxel-by-voxel correlation was positive, though the hottest regions were dissimilarly distributed in FLT-PET compared to FDG-PET. FLT-SUV_peak was not correlated with ADC_median, and voxel-by-voxel analyses and spatial distribution of aggressive areas varied with no systematic relation. LT-SUV_peak was significantly lower in responding lesions than non-responding lesions (mean FLT-SUV_peak in T-sites: 1.5 vs. 5.7; p = 0.007, mean FLT-SUV_peak in N-sites: 1.6 vs. 2.2; p = 0.013).

Conclusions

FLT-PET and DW-MRI performed early after treatment start may add biological information in patients with SCLC. Proliferation early after treatment start measured by FLT-PET is a promising predictor for final treatment response that warrants further investigation.

Trial registration

Clinicaltrials.gov, NCT02995902. Registered 11 December 2014 - Retrospectively registered.

A framework based on hidden Markov trees for multimodal PET/CT image co-segmentation

PURPOSE

The purpose of this study was to investigate the use of a probabilistic quad-tree graph (hidden Markov tree, HMT) to provide fast computation, robustness and an interpretational framework for multimodality image processing and to evaluate this framework for single gross tumor target (GTV) delineation from both positron emission tomography (PET) and computed tomography (CT) images.

METHODS

We exploited joint statistical dependencies between hidden states to handle the data stack using multi-observation, multi-resolution of HMT and Bayesian inference. This framework was applied to segmentation of lung tumors in PET/CT datasets taking into consideration simultaneously the CT and the PET image information. PET and CT images were considered using either the original voxels intensities, or after wavelet/contourlet enhancement. The Dice similarity coefficient (DSC), sensitivity (SE), positive predictive value (PPV) were used to assess the performance of the proposed approach on one simulated and 15 clinical PET/CT datasets of non-small cell lung cancer (NSCLC) cases. The surrogate of truth was a statistical consensus (obtained with the Simultaneous Truth and Performance Level Estimation algorithm) of three manual delineations performed by experts on fused PET/CT images. The proposed framework was applied to PET-only, CT-only and PET/CT datasets, and were compared to standard and improved fuzzy c-means (FCM) multimodal implementations.

RESULTS

A high agreement with the consensus of manual delineations was observed when using both PET and CT images. Contourlet-based HMT led to the best results with a DSC of 0.92 ± 0.11 compared to 0.89 ± 0.13 and 0.90 ± 0.12 for Intensity-based HMT and Wavelet-based HMT, respectively. Considering PET or CT only in the HMT led to much lower accuracy. Standard and improved FCM led to comparatively lower accuracy than HMT, even when considering multimodal implementations.

CONCLUSIONS

We evaluated the accuracy of the proposed HMT-based framework for PET/CT image segmentation. The proposed method reached good accuracy, especially with pre-processing in the contourlet domain.

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.

Decision support systems for personalized and participative radiation oncology

A paradigm shift from current population based medicine to personalized and participative medicine is underway. This transition is being supported by the development of clinical decision support systems based on prediction models of treatment outcome. In radiation oncology, these models 'learn' using advanced and innovative information technologies (ideally in a distributed fashion - please watch the animation: http://youtu.be/ZDJFOxpwqEA) from all available/appropriate medical data (clinical, treatment, imaging, biological/genetic, etc.) to achieve the highest possible accuracy with respect to prediction of tumor response and normal tissue toxicity. In this position paper, we deliver an overview of the factors that are associated with outcome in radiation oncology and discuss the methodology behind the development of accurate prediction models, which is a multi-faceted process. Subsequent to initial development/validation and clinical introduction, decision support systems should be constantly re-evaluated (through quality assurance procedures) in different patient datasets in order to refine and re-optimize the models, ensuring the continuous utility of the models. In the reasonably near future, decision support systems will be fully integrated within the clinic, with data and knowledge being shared in a standardized, dynamic, and potentially global manner enabling truly personalized and participative medicine.

Involved field radiotherapy (IFRT) versus elective nodal irradiation (ENI) for locally advanced non-small cell lung cancer: a meta-analysis of incidence of elective nodal failure (ENF)

Background and purpose

The use of involved field radiotherapy (IFRT) has generated concern about the increasing incidence of elective nodal failure (ENF) in contrast to elective nodal irradiation (ENI). This meta-analysis aimed to provide more reliable and up-to-date evidence on the incidence of ENF between IFRT and ENI.

Materials and methods

We searched three databases for eligible studies where locally advanced non-small cell lung cancer (NSCLC) patients received IFRT or ENI. Outcome of interest was the incidence of ENF. The fixed-effects model was used to pool outcomes across the studies.

Results

There were 3 RCTs and 3 cohort studies included with low risk of bias. There was no significant difference in incidence of ENF between IFRT and ENI either among RCTs (RR = 1.38, 95 % CI: 0.59–3.25, p = 0.46) or among cohort studies (RR = 0.99, 95 % CI: 0.46–2.10, p = 0.97). There was also no significant difference in incidence of ENF between IFRT and ENI when RCTs and cohort studies were combined (RR = 1.15, 95 % CI: 0.65–2.01, p = 0.64). I² of test for heterogeneity was 0 %.

Conclusion

This meta-analysis provides more reliable and stable evidence that there is no significant difference in incidence of ENF between IFRT and ENI.

Electronic supplementary material

The online version of this article (doi:10.1186/s13014-016-0698-3) contains supplementary material, which is available to authorized users.

Standardized Uptake Decrease on [18F]-Fluorodeoxyglucose Positron Emission Tomography After Neoadjuvant Chemotherapy Is a Prognostic Classifier for Long-Term Outcome After Multimodality Treatment: Secondary Analysis of a Randomized Trial for Resectable Stage IIIA/B Non-Small-Cell Lung Cancer

PURPOSE

A confirmatory analysis was performed to determine the prognostic value of metabolic response during induction chemotherapy followed by bimodality/trimodality treatment of patients with operable locally advanced non-small-cell lung cancer.

PATIENTS AND METHODS

Patients with potentially operable stage IIIA(N2) or selected stage IIIB non-small-cell lung cancer received three cycles of cisplatin/paclitaxel (induction chemotherapy) followed by neoadjuvant radiochemotherapy (RCT) to 45 Gy (1.5 Gy twice per day concurrent cisplatin/vinorelbine) within the ESPATUE (Phase III Study of Surgery Versus Definitive Concurrent Chemoradiotherapy Boost in Patients With Resectable Stage IIIA[N2] and Selected IIIB Non-Small-Cell Lung Cancer After Induction Chemotherapy and Concurrent Chemoradiotherapy) trial. Positron emission tomography scans were recommended before (t0) and after (t2) induction chemotherapy. Patients who were eligible for surgery after neoadjuvant RCT were randomly assigned to definitive RCT or surgery. The prognostic value of percentage of maximum standardized uptake value (%SUVmax) remaining in the primary tumor after induction chemotherapy-%SUVremaining = SUVmax(t2)/SUVmax(t0)-was assessed by proportional hazard analysis and receiver operating characteristic analysis.

RESULTS

Overall, 161 patients were randomly assigned (155 from the Essen and Tübingen centers), and 124 of these received positron emission tomography scans at t0 and t2. %SUVremaining as a continuous variable was prognostic for the three end points of overall survival, progression-free survival, and freedom from extracerebral progression in univariable and multivariable analysis (P < .016). The respective hazard ratios per 50% increase in %SUVremaining from multivariable analysis were 2.3 (95% CI, 1.5 to 3.4; P < .001), 1.8 (95% CI, 1.3 to 2.5; P < .001), and 1.8 (95% CI, 1.2 to 2.7; P = .006) for the three end points. %SUVremaining dichotomized at a cut point of maximum sum of sensitivity and specificity from receiver operating characteristic analysis at 36 months was also prognostic. Exploratory analysis revealed that %SUVremaining was likewise prognostic for overall survival in both treatment arms and was more closely associated with extracerebral distant metastases (P = .016) than with isolated locoregional relapses (P = .97).

CONCLUSION

%SUVremaining is a predictor for survival and other end points after multimodality treatment and can serve as a parameter for treatment stratification after induction chemotherapy or for evaluation of adjuvant new systemic treatment options for high-risk patients.

Evaluating tumor response of non-small cell lung cancer patients with ¹⁸F-fludeoxyglucose positron emission tomography: potential for treatment individualization

OBJECTIVE

To assess early tumor responsiveness and the corresponding effective radiosensitivity for individual patients with non-small cell lung cancer (NSCLC) based on 2 successive (18)F-fludeoxyglucose positron emission tomography (FDG-PET) scans.

METHODS AND MATERIALS

Twenty-six NSCLC patients treated in Maastricht were included in the study. Fifteen patients underwent sequential chemoradiation therapy, and 11 patients received concomitant chemoradiation therapy. All patients were imaged with FDG before the start and during the second week of radiation therapy. The sequential images were analyzed in relation to the dose delivered until the second image. An operational quantity, effective radiosensitivity, αeff, was determined at the voxel level. Correlations were sought between the average αeff or the fraction of negative αeff values and the overall survival at 2 years. Separate analyses were performed for the primary gross target volume (GTV), the lymph node GTV, and the clinical target volumes (CTVs).

RESULTS

Patients receiving sequential treatment could be divided into responders and nonresponders, using a threshold for the average αeff of 0.003 Gy(-1) in the primary GTV, with a sensitivity of 75% and a specificity of 100% (P<.0001). Choosing the fraction of negative αeff as a criterion, the threshold 0.3 also had a sensitivity of 75% and a specificity of 100% (P<.0001). Good prognostic potential was maintained for patients receiving concurrent chemotherapy. For lymph node GTV, the correlation had low statistical significance. A cross-validation analysis confirmed the potential of the method.

CONCLUSIONS

Evaluation of the early response in NSCLC patients showed that it is feasible to determine a threshold value for effective radiosensitivity corresponding to good response. It also showed that a threshold value for the fraction of negative αeff could also be correlated with poor response. The proposed method, therefore, has potential to identify candidates for more aggressive strategies to increase the rate of local control and also avoid exposing to unnecessary aggressive therapies the majority of patients responding to standard treatment.

Towards multidimensional radiotherapy: key challenges for treatment individualisation

Functional and molecular imaging of tumours have offered the possibility of redefining the target in cancer therapy and individualising the treatment with a multidimensional approach that aims to target the adverse processes known to impact negatively upon treatment result. Following the first theoretical attempts to include imaging information into treatment planning, it became clear that the biological features of interest for targeting exhibit considerable heterogeneity with respect to magnitude, spatial, and temporal distribution, both within one patient and between patients, which require more advanced solutions for the way the treatment is planned and adapted. Combining multiparameter information from imaging with predictive information from biopsies and molecular analyses as well as in treatment monitoring of tumour responsiveness appears to be the key approach to maximise the individualisation of treatment. This review paper aims to discuss some of the key challenges for incorporating into treatment planning and optimisation the radiobiological features of the tumour derived from pretreatment PET imaging of tumour metabolism, proliferation, and hypoxia and combining them with intreatment monitoring of responsiveness and other predictive factors with the ultimate aim of individualising the treatment towards the maximisation of response.

[Status and advances of RGD molecular imaging in lung cancer]

肺癌是国内外最常见、死亡率最高的恶性肿瘤之一。持续的新生血管生成是恶性肿瘤的特征，是肿瘤增殖、浸润、复发和转移的基础，也是目前肺癌生物学治疗热点之一。肿瘤血管生成过程中，整合素的作用至关重要。精氨酸-甘氨酸-天冬氨酸（Arg-Gly-Asp, RGD）肽能特异地与整合素结合，应用放射性核素标记的RGD分子探针，可使肿瘤血管显像，能反映肿瘤血管的变化。本文对近年来国内外RGD肽的肺癌显像研究进展进行综述。

Prediction of survival and cancer recurrence using metabolic volumetric parameters measured by 18F-FDG PET/CT in patients with surgically resected rectal cancer

OBJECTIVE

The goal of the present study was to determine whether the volumetric parameters such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG) measured by F-FDG PET/CT could be used as prognostic factors for the recurrence-free survival (RFS) and overall survival (OS) in patients with surgically resected rectal cancer.

PATIENTS AND METHODS

A retrospective review identified 73 patients with surgically resected rectal cancer who received F-FDG PET/CT. Survival analysis was conducted using Kaplan-Meier analysis, and survival curves stratified by age, sex, lymph node status, surgical resection margin, American Joint Committee on Cancer (AJCC) stage, and volumetric parameters of F-FDG PET/CT were generated for the estimation of OS and RFS. Independent predictive factors for survival were determined using Cox proportional hazards model.

RESULTS

High MTV, high TLG, advanced AJCC stage, lymph node (+), and surgical margin (+) group showed shorter OS in rectal cancer patients. Cox proportional hazards regression analysis showed that only surgical margin (+) was associated with poor OS. The early AJCC stage, lower MTV, and lower TLG were associated with better RFS in the current study. Cox proportional hazards regression analysis reveals that the surgical margin (+) was the potent predictor of OS. However, none of the factors was associated with RFS.

CONCLUSIONS

In conclusion, the results of this study suggest that volumetric parameters of F-FDG PET/CT could be significant prognostic factors in surgically resected rectal cancer.

4D PET/CT as a Strategy to Reduce Respiratory Motion Artifacts in FDG-PET/CT

The improved accuracy in tumor identification with FDG-PET has led to its increased utilization in target volume delineation for radiotherapy treatment planning in the treatment of lung cancer. However, PET/CT has constantly been influenced by respiratory motion-related image degradation, which is especially prominent for small lung tumors in the peri-diaphragmatic regions of the thorax. Here, we describe the current findings on respiratory motion-related image degradation in PET/CT, which may bring uncertainties to target volume delineation for image guided radiotherapy (IGRT) for lung cancer. Furthermore, we describe the evidence suggesting 4D PET/CT to be one strategy to minimize the impact of respiratory motion-related image degradation on tumor target delineation for thoracic IGRT. This, in our opinion, warrants further investigation in future IGRT-based lung cancer trials.

Biologic targets identified from dynamic 18FDG-PET and implications for image-guided therapy

PURPOSE

The outcome of biologic image-guided radiotherapy depends on the definition of the biologic target. The purpose of the current work was to extract hyperperfused and hypermetabolic regions from dynamic positron emission tomography (D-PET) images, to dose escalate either region and to discuss implications of such image guided strategies.

METHODS

Eleven patients with soft tissue sarcomas were investigated with D-PET. The images were analyzed using a two-compartment model producing parametric maps of perfusion and metabolic rate. The two image series were segmented and exported to a treatment planning system, and biological target volumes BTVper and BTVmet (perfusion and metabolism, respectively) were generated. Dice's similarity coefficient was used to compare the two biologic targets. Intensity-modulated radiation therapy (IMRT) plans were generated for a dose painting by contours regime, where planning target volume (PTV) was planned to 60 Gy and BTV to 70 Gy. Thus, two separate plans were created for each patient with dose escalation of either BTVper or BTVmet.

RESULTS

BTVper was somewhat smaller than BTVmet (209 ± 170 cm(3) against 243 ± 143 cm(3), respectively; population-based mean and s.d.). Dice's coefficient depended on the applied margin, and was 0.72 ± 0.10 for a margin of 10 mm. Boosting BTVper resulted in mean dose of 69 ± 1.0 Gy to this region, while BTVmet received 67 ± 3.2 Gy. Boosting BTVmet gave smaller dose differences between the respective non-boost DVHs (such as D98).

CONCLUSIONS

Dose escalation of one of the BTVs results in a partial dose escalation of the other BTV as well. If tumor aggressiveness is equally pronounced in hyperperfused and hypermetabolic regions, this should be taken into account in the treatment planning.

Use of PET/CT for patient selection and radiation therapy target volume definition in patients with non-small-cell lung cancer

SUMMARY PET scanning is having an increasing impact on the treatment of non-small-cell lung cancer with radiation therapy (RT) and chemoRT. It has a powerful impact on staging, often revealing evidence of more advanced, frequently incurable, disease in patients who would otherwise be considered suitable for treatment with potentially curative definitive RT. Approximately a third of curative RT candidates are found to be unsuitable for this often highly toxic form of treatment after PET, thereby ensuring that this intensive treatment is only given to those patients who might benefit from it. If a patient remains suitable for treatment with RT after PET staging, PET can play a further critical role in the targeting of the RT. Without the use of PET in this way, a quarter of patients or more would experience geographic misses, in which some tumor regions would be either underdosed or excluded entirely from treatment, thereby compromising the chances of a successful outcome. There is emerging evidence that the overall results of treatment with RT can be improved by the appropriate use of PET in non-small-cell lung cancer.

Combined radio- and chemotherapy for non-small cell lung cancer: systematic review of landmark studies based on acquired citations

The important role of combined chemoradiation for several groups of patients with non-small cell lung cancer (NSCLC) is reflected by the large number of scientific articles published during the last 30 years. Different measures of impact and clinical relevance of published research are available, each with its own pros and cons. For this review, article citation rate was chosen. Highly cited articles were identified through systematic search of the citation database Scopus. Among the 100 most often cited articles, meta-analyses (n = 5) achieved a median of 203 citations, guidelines (n = 7) 97, phase III trials (n = 29) 168, phase II trials (n = 21) 135, phase I trials (n = 7) 88, and others combined 115.5 (p = 0.001). Numerous national and international cooperative groups and several single institutions were actively involved in performing often cited, high-impact trials, reflecting the fact that NSCLC is a world-wide challenge that requires research collaboration. Platinum-containing combinations have evolved into a standard of care, typically administered concurrently. The issue of radiotherapy fractionation and total dose has also been studied extensively, yet with less conclusive results. Differences in target volume definition have been addressed. However, it was not possible to test all theoretically possible combinations of radiotherapy regimens, drugs, and drug doses (lower radiosensitizing doses compared to higher systemically active doses). That is why current guidelines offer physicians a choice of different, presumably equivalent treatment alternatives. This review identifies open questions and strategies for further research.

Predicting outcomes in radiation oncology--multifactorial decision support systems

With the emergence of individualized medicine and the increasing amount and complexity of available medical data, a growing need exists for the development of clinical decision-support systems based on prediction models of treatment outcome. In radiation oncology, these models combine both predictive and prognostic data factors from clinical, imaging, molecular and other sources to achieve the highest accuracy to predict tumour response and follow-up event rates. In this Review, we provide an overview of the factors that are correlated with outcome-including survival, recurrence patterns and toxicity-in radiation oncology and discuss the methodology behind the development of prediction models, which is a multistage process. Even after initial development and clinical introduction, a truly useful predictive model will be continuously re-evaluated on different patient datasets from different regions to ensure its population-specific strength. In the future, validated decision-support systems will be fully integrated in the clinic, with data and knowledge being shared in a standardized, instant and global manner.

A semiautomatic CT-based ensemble segmentation of lung tumors: comparison with oncologists' delineations and with the surgical specimen

PURPOSE

To assess the clinical relevance of a semiautomatic CT-based ensemble segmentation method, by comparing it to pathology and to CT/PET manual delineations by five independent radiation oncologists in non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

For 20 NSCLC patients (stages Ib-IIIb) the primary tumor was delineated manually on CT/PET scans by five independent radiation oncologists and segmented using a CT based semi-automatic tool. Tumor volume and overlap fractions between manual and semiautomatic-segmented volumes were compared. All measurements were correlated with the maximal diameter on macroscopic examination of the surgical specimen. Imaging data are available on www.cancerdata.org.

RESULTS

High overlap fractions were observed between the semi-automatically segmented volumes and the intersection (92.5±9.0, mean±SD) and union (94.2±6.8) of the manual delineations. No statistically significant differences in tumor volume were observed between the semiautomatic segmentation (71.4±83.2 cm(3), mean±SD) and manual delineations (81.9±94.1 cm(3); p=0.57). The maximal tumor diameter of the semiautomatic-segmented tumor correlated strongly with the macroscopic diameter of the primary tumor (r=0.96).

CONCLUSIONS

Semiautomatic segmentation of the primary tumor on CT demonstrated high agreement with CT/PET manual delineations and strongly correlated with the macroscopic diameter considered as the "gold standard". This method may be used routinely in clinical practice and could be employed as a starting point for treatment planning, target definition in multi-center clinical trials or for high throughput data mining research. This method is particularly suitable for peripherally located tumors.

Comparison of different methods of incorporating respiratory motion for lung cancer tumor volume delineation on PET images: a simulation study

The interest of PET complementary information for the delineation of the target volume in radiotherapy of lung cancer is increasing. However, respiratory motion requires the determination of a functional internal target volume (ITV) on PET images for which several strategies have been proposed. The purpose of this study was the comparison of these strategies for taking into account respiratory motion and deriving the ITV: (1) adding fixed margins to the volume defined on a single binned image, (2) segmenting a motion averaged image and (3) considering the union of volumes delineated on binned frames. For this third strategy, binned frames were either non-corrected for motion, or corrected using two different methods: elastic registration or super resolution. The strategies' performances were assessed on realistic simulated datasets combining the NCAT phantom with a PET Philips GEMINI scanner model in GATE, and containing various configurations of tumor to background contrast, with both regular and irregular respiratory motion (with a range of motion amplitudes). The obtained ITVs' sensitivity (SE) and positive predictive value (PVE) with respect to the known true ITV were significantly higher (from 0.8 to 0.95) than all other techniques when using binned frames corrected for motion, independently of motion regularity, amplitude, or tumor to background contrast. Although the absolute difference was small and not always significant, images corrected using super resolution led to systematically better results than using elastic registration. The worst results were obtained when using the motion averaged image for SE (around 0.5-0.6) and using the margins added to a single frame for PPV (0.6-0.7), respectively. The best strategy to account for breathing motion for tumor ITV delineation in radiotherapy planning is to rely on the use of the union of volumes delineated on super resolution-corrected binned images.

Prognostic value of metabolic volume measured by F-18 FDG PET-CT in patients with esophageal cancer

PURPOSE

  The aim of this study was to evaluate the usefulness of the metabolic tumor volume (MTV) measured by F-18 Fluorodeoxyglucose positron emission tomography (FDG PET-CT) in predicting recurrence free survival (RFS) in patients with esophageal cancer.

METHODS

  Forty-five patients with squamous cell carcinoma, who had undergone whole-body F-18 FDG PET-CT scans before surgical resection, were included in this study. All patients were treated with Ivor-Lewis esophagectomy. The MTV was quantified within the primary tumor using the 50% threshold of the maximum standardized uptake value (SUV_max ) of the FDG uptake areas. The cutoff value of MTV₅₀ was determined through receiver-operating characteristic curve. The Kaplan Meier method was used to find out the relationship between RFS and MTV₅₀ . Univariate analysis and multivariate proportional hazards regression analysis were applied to test the significance of volumetric parameter of F-18 FDG PET-CT and other conventional prognostic factors for the prediction of RFS.

RESULTS

  Overall median follow up period was 17.87 months (range: 1.07-63.27 months). The median survival between treatment completion and recurrence was 15.5 months (range: 1.37-72.43 months). Recurrence was found in eight patients. On univariate analysis, MTV₅₀ (P = 0.0032), N stage (P = 0.0004), American Joint Committee on Cancer stage (P = 0.0101), tumor location (P = 0.0054) and adjuvant treatment (P = 0.0373) were significant predictors of RFS. Multivariate analysis showed that the independent prognostic factors were MTV₅₀ (P = 0.0465), N stage (P = 0.0303) and tumor location (P = 0.0270).

CONCLUSION

  Volume based parameter of F-18 FDG PET-CT may have a role in providing prognostic information in esophageal cancer patients who received esophagectomy.

Prognostic value of volumetric parameters measured by F-18 FDG PET/CT in surgically resected non-small-cell lung cancer

OBJECTIVES

The aim of this study was to evaluate the usefulness of the tumor burden as characterized by the metabolic tumor volume (MTV) and total lesion glycolysis (TLG) measured by F-18 fluoro-2-deoxyglucose (F-18 FDG) PET-computed tomography (CT) in predicting recurrence-free survival (RFS) and overall survival (OS) in surgically resected non-small-cell lung cancer (NSCLC) patients.

METHODS

We retrospectively reviewed 91 patients with pathologically documented stages I-IIIA NSCLC. MTV and TLG were obtained according to various thresholds of the standard uptake value (SUV) of primary tumor using preoperative F-18 FDG PET-CT. We used comparison receiver-operating characteristic curve analysis to test the statistical significance of the differences among the multiple volumetric parameters calculated by various SUV cutoff values. RFS and OS were evaluated with the Kaplan-Meier method and Cox regression analysis.

RESULTS

On comparison receiver-operating characteristic curve analysis, no significant difference was found among the volumetric parameters calculated using various thresholds of SUV. Regardless of the thresholds, patients with smaller MTV and lower TLG showed longer RFS and OS. MTV and TLG measured by F-18 FDG PET-CT were found to have better predictive performance than SUVmax for recurrence and death. According to multivariate analyses, MTV2.5 was revealed as a significant prognostic factor for RFS. Tumor size over 3 cm was selected as a significant prognostic indicator of OS.

CONCLUSION

Volume-based parameters of F-18 FDG PET-CT may have a role in providing prognostic information in NSCLC patients who have received surgical treatment.

A review of clinical trials of cetuximab combined with radiotherapy for non-small cell lung cancer

Treatment of non-small cell lung cancer (NSCLC) is challenging in many ways. One of the problems is disappointing local control rates in larger volume disease. Moreover, the likelihood of both nodal and distant spread increases with primary tumour (T-) stage. Many patients are elderly and have considerable comorbidity. Therefore, aggressive combined modality treatment might be contraindicated or poorly tolerated. In many cases with larger tumour volume, sufficiently high radiation doses can not be administered because the tolerance of surrounding normal tissues must be respected. Under such circumstances, simultaneous administration of radiosensitizing agents, which increase tumour cell kill, might improve the therapeutic ratio. If such agents have a favourable toxicity profile, even elderly patients might tolerate concomitant treatment. Based on sound preclinical evidence, several relatively small studies have examined radiotherapy (RT) with cetuximab in stage III NSCLC. Three different strategies were pursued: 1) RT plus cetuximab (2 studies), 2) induction chemotherapy followed by RT plus cetuximab (2 studies) and 3) concomitant RT and chemotherapy plus cetuximab (2 studies). Radiation doses were limited to 60-70 Gy. As a result of study design, in particular lack of randomised comparison between cetuximab and no cetuximab, the efficacy results are difficult to interpret. However, strategy 1) and 3) appear more promising than induction chemotherapy followed by RT and cetuximab. Toxicity and adverse events were more common when concomitant chemotherapy was given. Nevertheless, combined treatment appears feasible. The role of consolidation cetuximab after RT is uncertain. A large randomised phase III study of combined RT, chemotherapy and cetuximab has been initiated.