The added value of metabolic imaging with FDG-PET in oesophageal cancer: prognostic role and prediction of response to treatment

Neoadjuvant treatment for advanced esophageal cancer: response assessment before surgery and how to predict response to chemoradiation before starting treatment

Patients with advanced esophageal cancer (T3-4, N) have a poor prognosis. Chemoradiation or chemotherapy before esophagectomy with adequate lymphadenectomy is the standard treatment for patients with resectable advanced esophageal carcinoma. However, only patients with major histopathologic response (regression to less than 10% of the primary tumor) after preoperative treatment will have a prognostic benefit of preoperative chemoradiation. Using current therapy regimens about 40% to 50% of the patients show major histopathological response. The remaining cohort does not benefit from this neoadjuvant approach but might benefit from earlier surgical resection. Therefore, it is an aim to develop tools for response prediction before starting the treatment and for early response assessment identifying responders. The current review discusses the different imaging techniques and the most recent studies about molecular markers for early response prediction. The results show that [(18)F]-fluorodeoxyglucose-positron emission tomography (FDG-PET) has a good sensitivity but the specificity is not robust enough for routine clinical use. Newer positron emission tomography detector technology, the combination of FDG-PET with computed tomography, additional evaluation criteria and standardization of evaluation may improve the predictive value. There exist a great number of retrospective studies using molecular markers for prediction of response. Until now the clinical use is missing. But the results of first prospective studies are promising. A future perspective may be the combination of imaging technics and special molecular markers for individualized therapy. Another aspect is the response assessment after finishing neoadjuvant treatment protocol. The different clinical methods are discussed. The results show that until now no non-invasive method is valid enough to assess complete histopathological response.

Role of positron emission tomography-computed tomography in gastrointestinal malignancies

Positron emission tomography (PET) has proved itself to be valuable in the evaluation of patients with a wide array of gastrointestinal (GI) malignancies. Subsequent development of fusion imaging with PET and computed tomography (PET-CT) scanners has significantly advanced the capabilities of imaging by combining the functional data of the(18)F-labeled glucose analogue fluorodeoxyglucose (FDG) with the conventional anatomic data provided by CT. This article reviews the evolving role of FDG PET-CT imaging in the initial assessment and monitoring of GI tumors. Specific applications are discussed, and normal variants and benign findings frequently encountered during PET-CT of the GI tract are reviewed.

Molecular imaging in tumor angiogenesis and relevant drug research

Molecular imaging, including fluorescence imaging (FMI), bioluminescence imaging (BLI), positron emission tomography (PET), single-photon emission-computed tomography (SPECT), and computed tomography (CT), has a pivotal role in the process of tumor and relevant drug research. CT, especially Micro-CT, can provide the anatomic information for a region of interest (ROI); PET and SPECT can provide functional information for the ROI. BLI and FMI can provide optical information for an ROI. Tumor angiogenesis and relevant drug development is a lengthy, high-risk, and costly process, in which a novel drug needs about 10–15 years of testing to obtain Federal Drug Association (FDA) approval. Molecular imaging can enhance the development process by understanding the tumor mechanisms and drug activity. In this paper, we focus on tumor angiogenesis, and we review the characteristics of molecular imaging modalities and their applications in tumor angiogenesis and relevant drug research.

Personalized versus evidence-based medicine with PET-based imaging

In this Perspective the feasibility, scope and impact of integrating PET-based personalized medicine into the evidence-based clinical practice of oncology is discussed. The basic concepts of 'evidence-based medicine' and 'personalized medicine' at times seem contradictory; however, I will discuss, with specific clinical situations as examples, a synergistic and probably incremental link between the two and propose that the result of such integration will ultimately improve patient management. Tailoring therapeutic approaches and regimens by molecular imaging, with PET at its forefront, would enable disease management at the individual level and this modification would hopefully further strengthen the evidence-based approach in oncology.

Prognostic significance of SUV on PET/CT in patients with esophageal cancer: a systematic review and meta-analysis

BACKGROUND AND PURPOSE

Esophageal cancer is the third most common gastrointestinal malignancy with a poor long-term survival and high mortality. Surgical resection provides the only chance of cure. The tumor-node metastasis stage classification system is a strong prognostic parameter predicting the prognosis. We performed the present meta-analysis to comprehensively review the evidence for use of standardized uptake value (SUV) measured on tumor to predict prognosis of esophageal cancer.

METHODS

We searched for articles published in English or Chinese; limited to esophageal cancer; F-fluoro-2-deoxy-glucose (F-FDG) uptake on positron emission tomography (PET) performed on a dedicated device; dealt with the impact of SUV on survival. We extracted an estimate of the log hazard ratios (HR) and their variances and performed meta-analysis.

RESULTS

Without the study dealt by the pretreatment SUV measured on metastasis sites, there were seven studies dealt by the prognostic value of SUV measured on FDG-PET for overall survival. The combined HR was 1.86, meaning that high SUV indicated worse survival prognosis; and there were three studies dealt with the prognostic value of SUV measured on FDG-PET for disease-free survival. The combined HR was 2.52, indicating that high SUV was associated with more significantly higher risk for recurrence than low SUV.

CONCLUSION

SUV measured in patients with esophageal cancer, reflecting the metabolic activity of tumor and malignancy, could serve as a prognostic factor. Considering that the FDG-PET can add important information of metabolism in detection and staging to conventional imaging modality, we anticipate that SUV could be used in patients with esophageal carcinoma.

Molecular imaging in drug development

Molecular imaging can allow the non-invasive assessment of biological and biochemical processes in living subjects. Such technologies therefore have the potential to enhance our understanding of disease and drug activity during preclinical and clinical drug development, which could aid decisions to select candidates that seem most likely to be successful or to halt the development of drugs that seem likely to ultimately fail. Here, with an emphasis on oncology, we review the applications of molecular imaging in drug development, highlighting successes and identifying key challenges that need to be addressed for successful integration of molecular imaging into the drug development process.

Semiautomatic volume of interest drawing for 18F-FDG image analysis—method and preliminary results

PURPOSE

Functional imaging of cancer adds important information to the conventional measurements in monitoring response. Serial (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET), which indicates changes in glucose metabolism in tumours, shows great promise for this. However, there is a need for a method to quantitate alterations in uptake of FDG, which accounts for changes in tumour volume and intensity of FDG uptake. Selection of regions or volumes [ROI or volumes of interest (VOI)] by hand drawing, or simple thresholding, suffers from operator-dependent drawbacks.

MATERIALS AND METHODS

We present a simple, robust VOI growing method for this application. The method requires a single seed point within the visualised tumour and another in relevant normal tissue. The drawn tumour VOI is insensitive to the operator inconsistency and is, thus, a suitable basis for comparative measurements. The method is validated using a software phantom. We demonstrate the use of the method in the assessment of tumour response in 31 patients receiving chemotherapy for various carcinomas.

RESULTS

Valid assessment of tumour response could be made 2-4 weeks after starting chemotherapy, giving information for clinical decision making which would otherwise have taken 9-12 weeks. Survival was predicted from FDG-PET 2-4 weeks after starting chemotherapy (p = 0.04) and after 9-12 weeks FDG-PET gave a better prediction of survival (p = 0.002) than CT or MRI (p = 0.015).

CONCLUSIONS

FDG-PET using this method of analysis has potential as a routine tool for optimising use of chemotherapy and improving its cost effectiveness. It also has potential for increasing the accuracy of response assessment in clinical trials of novel therapies.