Can hybrid FDG-PET/CT detect subclinical lymph node metastasis of esophageal cancer appropriately and contribute to radiation treatment planning? A comparison of image-based and pathological findings

18F-Fluorodeoxyglucose Positron Emission Tomography Parameters can Predict Long-Term Outcome Following Trimodality Treatment for Oesophageal Cancer

AIMS

¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸FDG-PET/CT) is routinely used for the pre-treatment staging of oesophageal or gastro-oesophageal junction cancers (EGEJC). The aim of this study was to identify objective ¹⁸FDG-PET/CT-derived parameters that can aid in predicting the patterns of recurrence and prognostication in patients with EGEJC.

PATIENTS AND METHODS

EGEJC patients referred for consideration of preoperative chemoradiation therapy were identified and clinicopathological data were collected. ¹⁸FDG-PET/CT imaging data were reviewed and correlated with treatment outcomes. Maximum standardised uptake value (SUV_max), metabolic tumour volume (MTV) and total lesion glycolysis were assessed and association with recurrence-free survival (RFS), locoregional recurrence-free survival (LR-RFS), oesophageal cancer-specific survival (ECSS) and overall survival were evaluated using receiver operating characteristic curves, as well as Cox regression and Kaplan-Meier models.

RESULTS

In total, 191 EGEJC patients completed trimodality treatment and 164 with ¹⁸FDG-PET/CT data were included in this analysis. At the time of analysis, 15 (9.1%), 70 (42.7%) and two (1.2%) patients were noted to have locoregional, distant and both locoregional and distant metastases, respectively. The median RFS was 30 months (9.6-50.4) and the 5-year RFS was 31.1%. The 5-year overall survival and ECSS were both noted to be 34.8%. Pre-treatment MTV₂₅ > 28.5 cm³ (P = 0.029), MTV₄₀ > 12.4 cm³ (P = 0.018) and MTV₅₀ > 10.2 cm³ (P = 0.005) predicted for worse LR-RFS, ECSS and overall survival for MTV definition of voxels ≥25%, 40% and 50% of SUV_max.

CONCLUSION

¹⁸FDG-PET/CT parameters MTV and total lesion glycolysis are useful prognostic tools to predict for LR-RFS, ECSS and overall survival in EGEJC. MTV had the highest accuracy in predicting clinical outcomes. The volume cut-off points we identified for different MTV thresholds predicted outcomes with significant accuracy and may potentially be used for decision making in clinical practice.

Genome-wide Discovery of a Novel Gene-expression Signature for the Identification of Lymph Node Metastasis in Esophageal Squamous Cell Carcinoma

OBJECTIVE

This study aimed to develop a gene-expression signature for identification of lymph node (LN) metastasis in esophageal squamous cell carcinoma (ESCC) patients.

SUMMARY OF BACKGROUND DATA

LN metastasis is recognized as the most important independent risk factor for therapeutic decision-making of ESCC patients.

METHODS

A bioinformatic approach was used to analyze RNA sequencing profiles of ESCC patients, and to develop a gene-expression signature for identifying LN metastasis. The robustness of this panel was assessed in 2 independent patient cohorts (n = 56 and 224).

RESULTS

We initially prioritized a 16-gene signature out of the total 20,531 mRNAs. The model estimated by these 16 genes discriminated LN status with an area under the curve (AUC) of 0.77 [95% confidence interval (95% CI), 0.68-0.87, 5-fold cross-validation]. Subsequently, a reduced and optimized 5-gene panel was trained in a clinical cohort, which effectively distinguished ESCC patients with LN metastasis (cohort-1: AUC, 0.74; 95% CI, 0.58-0.89; cohort-2, T1-T2: AUC, 0.74; 95% CI, 0.63-0.86), and was significantly superior to preoperative computed tomography (AUC, 0.61; 95% CI, 0.50-0.72). Furthermore, a combination signature comprising of the 5-gene panel together with the lymphatic vessel invasion (LVI) and venous invasion (VI) demonstrated a significantly improved diagnostic performance compared with individual clinical variables, in both cohorts (cohort-1: AUC, 0.87; 95% CI, 0.78-0.96; cohort-2: AUC, 0.76; 95% CI, 0.65-0.88).

CONCLUSION

Our novel 5-gene panel is a robust diagnostic tool for LN metastasis, especially in early-T stage ESCC patients, with a promising clinical potential.

Sentinel node navigation surgery in esophageal cancer

Over the last 20 years, the sentinel node (SN) concept has been widely applied to the surgical staging of both breast cancer and melanoma. However, the validity of this concept has been controversial for esophageal cancer, because SN mapping for esophageal cancer is not considered to be technically easy because of the complicated multidirectional lymphatic networks of the esophagus and mediastinum. Nevertheless, studies including meta-analyses indicated that SN mapping may be feasible in early esophageal cancer. Transthoracic esophagectomy with three-field lymphadenectomy was developed as a potential curative procedure for thoracic esophageal cancer. However, this highly invasive procedure might increase morbidity and reduce patients' quality of life (QOL) after esophagectomy. Although further validation based on multicenter trials using the standard protocol of SN mapping for esophageal cancer is required, SN navigation surgery would enable us to carry out personalized and limited lymph node dissection which might reduce morbidity and maintain patients' QOL.

Molecular Imaging Using PET/CT for Radiation Therapy Planning for Adult Cancers: Current Status and Expanding Applications

Accurate tumor delineation is a priority in radiation therapy (RT). Metabolic imaging has a key and evolving role in target volume selection and delineation. This is especially so for non-small cell lung cancer, squamous cell cancer of the head and neck, and lymphoma, for which positron emission tomography/computed tomography (PET/CT) is complimentary to structural imaging modalities, not only in delineating primary tumors, but also often in revealing previously undiagnosed regional nodal disease. At some sites, PET/CT has been confirmed to enable target size reduction compared with structural imaging alone, with enhanced normal tissue sparing and potentially allowing for dose escalation. These contributions often dramatically affect RT strategies. However, some limitations exist to the use of fluorodeoxyglucose-PET in RT planning, including its relatively poor spatial resolution and partial voluming effects for small tumors. A role is developing for contributions from metabolic imaging to RT planning at other tumor sites and exciting new applications for the use of non-fluorodeoxyglucose metabolic markers for RT planning.

Small Cell/Neuroendocrine Tumors of the Esophagus: Presentation of Two Cases and Review of the Literature

Small cell cancers of the gastrointestinal tract are part of a family of extrapulmonary small cell carcinomas. These tumors can occur anywhere in the body and generally carry a poor prognosis. Treatment usually consists of a combination of chemotherapy and radiation therapy. We present two cases illustrating diagnostic and treatment issues and review the literature on the treatment of this uncommon but aggressive family of tumors. Free full text available at www.tumorionline.it

FDG-PET/CT lymph node staging after neoadjuvant chemotherapy in patients with adenocarcinoma of the esophageal-gastric junction

Objectives

The aim of the analysis was to assess the accuracy of various FDG-PET/CT parameters in staging lymph nodes after neoadjuvant chemotherapy.

Methods

In this prospective study, 74 patients with adenocarcinoma of the esophageal–gastric junction were examined by FDG-PET/CT in the course of their neoadjuvant chemotherapy given before surgical treatment. Data from the final FDG-PET/CT examinations were compared with the histology from the surgical specimens (gold standard). The accuracy was calculated for four FDG-PET/CT parameters: (1) hypermetabolic nodes, (2) large nodes, (3) large-and-medium large nodes, and (4) hypermetabolic or large nodes.

Results

In 74 patients, a total of 1540 lymph nodes were obtained by surgery, and these were grouped into 287 regions according to topographic origin. Five hundred and two nodes were imaged by FDG-PET/CT and were grouped into these same regions for comparison. In the analysis, (1) hypermetabolic nodes, (2) large nodes, (3) large-and-medium large nodes, and (4) hypermetabolic or large nodes identified metastases in particular regions with sensitivities of 11.6%, 2.9%, 21.7%, and 13.0%, respectively; specificity was 98.6%, 94.5%, 74.8%, and 93.6%, respectively. The best accuracy of 77.7% reached the parameter of hypermetabolic nodes. Accuracy decreased to 62.0% when also smaller nodes (medium-large) were taken for the parameter of metastases.

Conclusions

FDG-PET/CT proved low sensitivity and high specificity. Low sensitivity was based on low detection rate (32.6%) when compared nodes imaged by FDG-PET/CT to nodes found by surgery, and in inability to detect micrometastases. Sensitivity increased when also medium-large LNs were taken for positive, but specificity and accuracy decreased.

Accuracy of ultrasound for the diagnosis of cervical lymph node metastasis in esophageal cancer: a systematic review and meta-analysis

BACKGROUND

Esophageal cancer is considered a serious malignancy with respect to its prognosis and mortality rate. Cervical lymph node status is one of the keys to determining prognosis and treatment methods. However, published data vary regarding the accuracy of ultrasound in the diagnosis of cervical lymph node metastasis. We performed a meta-analysis to assess the efficacy of ultrasound for detecting cervical lymph node metastasis in patients with esophageal cancer.

METHODS

The PubMed/MEDLINE, EMBASE, Web of Science, and Cochrane Library databases were searched to identify studies related to cervical lymph node metastasis, and 22 studies comprising 3,513 patients met our inclusion criteria. We used a bivariate meta-analysis following a random effects model to summarize the data. We also explored reasons for statistical heterogeneity using meta-regression, subgroup, and sensitivity analyses. Publication bias was assessed with a Deeks funnel plot.

RESULTS

The area under the receiver operating characteristic curve was 0.97 [95% confidence interval (CI): 0.95-0.98], and the pooled diagnostic odds ratio was 121.00 (95% CI: 47.57-307.79). With cut-off values of 5 mm and >5 mm for cervical lymph node size, the sensitivities and specificities (95% confidence interval) for ultrasound detection of cervical lymph node metastasis were 84% (67-93%) and 93% (90-95%); and 94% (76-98%) and 98% (89-100%), respectively.

CONCLUSIONS

We show for the first time the diagnostic accuracy of ultrasound for predicting cervical lymph node-positive metastasis in esophageal cancer. Our analysis shows that ultrasonography may be an effective and reliable approach to detect cervical lymph node metastasis in esophageal cancer. However, to accommodate heterogeneity, high-quality studies are needed to further verify the efficacy of ultrasound detection.

Application of Endobronchial Ultrasonography for the Preoperative Detecting Recurrent Laryngeal Nerve Lymph Node Metastasis of Esophageal Cancer

BACKGROUND

The preoperative detection of recurrent laryngeal nerve lymph node (RLN LN) metastasis provides important information for the treatment of esophageal cancer. We investigated the possibility of applying endobronchial ultrasonography (EBUS) with conventional preoperative endoscopic ultrasonography (EUS) and computerized tomography (CT) examination to evaluate RLN LN metastasis in patients with esophageal cancer.

METHODS

A total of 115 patients with advanced thoracic esophageal cancer underwent EBUS examinations. Patients also underwent EUS and CT imaging as reference diagnostic methods. Positron emission tomography /computed tomography (PET/CT) was also introduced in partial patients as reference method. The preoperative evaluation of RLN LN metastasis was compared with the surgical and pathological staging in 94 patients who underwent radical surgery.

RESULTS

The sensitivities of the preoperative evaluations of RLN LN metastasis by EBUS, EUS and CT were 67.6%, 32.4% and 29.4%, respectively. The sensitivity of EBUS was significantly different from that of EUS or CT, especially in the detection of right RLN LNs. In addition, according to the extra data from reference method, PET/CT was not superior to EBUS or EUS in detecting RLN LN metastasis. Among all 115 patients, 21 patients who were diagnosed with tracheal invasions by EUS or EBUS avoided radical surgery. Another 94 patients who were diagnosed as negative for tracheobronchial tree invasion by EUS and EBUS had no positive findings in radical surgery.

CONCLUSIONS

EBUS can enhance the preoperative sensitivity of the detection of RLN LN metastasis in cases of thoracic esophageal cancer and is a useful complementary examination to conventional preoperative EUS and CT, which can alert thoracic surgeons to the possibility of a greater range of preoperative lymph node dissection. EBUS may also indicate tracheal invasion in cases of esophageal stricture.

Curative treatment of esophageal cancer; an evidenced based review

BACKGROUND

In 2013, roughly 18,000 cases of esophageal cancer will be diagnosed in the United States with more than 15,000 people dying from the disease. Worldwide, an estimated 482,300 new esophageal cancer cases were diagnosed with 406,800 deaths in 2008. Squamous cell carcinoma (SCC) and adenocarcinoma (AC) account for >90% of all esophageal cancer cases.

METHODS

The authors will examine the role of radiation therapy, chemotherapy, and surgery in the curative management of esophageal cancer by examining randomized control data, single arm phase II trials, several recently published meta-analyses, as well as retrospective data where there is no clinical trial data available. The role of positron emission tomography (PET) will be reviewed as well.

RESULTS

Current data support the role of neoadjuvant chemoradiotherapy followed by surgical resection for locally advanced esophageal cancer with 3-year overall survival ranging from 30% to 60%. The benefit of adjuvant chemoradiation therapy is limited to margin positive and/or node positive patients. There is emerging data questioning the survival benefit of surgical resection after chemoradiotherapy. External beam radiation therapy alone results in very few long-term survivors and is considered palliative at best. Radiation dose-escalation has failed to improve local control or survival. PET scanning is vital in staging and has become a strong predictor of response and survival.

CONCLUSIONS

Preoperative or definitive concurrent chemoradiotherapy is the established standard of care for locally advanced cancers of the esophagus. While preoperative chemotherapy is supported by level 1 evidence, the true benefit of induction chemotherapy before chemoradiotherapy has not been established in a prospective randomized control trial. The role of surgery in the management of SCC is still a hotly debated subject, however, it is still recommended for AC. There is no data to support adjuvant chemotherapy after preoperative chemoradiotherapy. The benefit of neoadjuvant chemotherapy seems to be limited AC. Radiation without chemotherapy is palliative and never curative. PET continues to be integrated into treatment decisions and predicts for response and survival after therapy.

Clinical relevance of novel imaging technologies for sentinel lymph node identification and staging

The sentinel lymph node (SLN) concept has become a standard of care for patients with breast cancer and melanoma, yet its clinical application to other cancer types has been somewhat limited. This is mainly due to the reduced accuracy of conventional SLN mapping techniques (using blue dye and/or radiocolloids as lymphatic tracers) in cancer types where lymphatic drainage is more complex, and SLNs are within close proximity to other nodes or the tumour site. In recent years, many novel techniques for SLN mapping have been developed including fluorescence, x-ray, and magnetic resonant detection. Whilst each technique has its own advantages/disadvantages, the role of targeted contrast agents (for enhanced retention in the SLN, or for immunostaging) is increasing, and may represent the new standard for mapping the SLN in many solid organ tumours. This review article discusses current limitations of conventional techniques, limiting factors of nanoparticulate based contrast agents, and efforts to circumvent these limitations with modern tracer architecture.

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.

Positron emission tomography imaging for gastroesophageal junction tumors

Positron emission tomography (PET) is now widely used in the initial evaluation of esophageal and gastroesophageal junction tumors. It can detect otherwise occult metastases, affecting staging and treatment in a significant proportion of patients. The intensity of PET uptake before treatment has been correlated with outcomes, but it remains uncertain whether PET is an independent prognostic factor for survival. An emerging application for PET is the assessment of response to induction chemotherapy or chemoradiotherapy. In particular, PET has the ability to discriminate treatment responders from nonresponders early in the course of induction chemotherapy. This can form the basis for further treatment decisions, such as a change in chemotherapy or the addition of concurrent radiotherapy, and this approach is now being tested in prospective trials. PET after concurrent chemoradiotherapy may also provide information regarding the utility of surgical resection. PET data can affect radiotherapy target definition, which may lead to improved tumor coverage in cases where the true extent of disease is not accurately reflected by computed tomography or endoscopic imaging.

Recommendations of the Spanish Societies of Radiation Oncology (SEOR), Nuclear Medicine & Molecular Imaging (SEMNiM), and Medical Physics (SEFM) on (18)F-FDG PET-CT for radiotherapy treatment planning

Positron emission tomography (PET) with (18)F-fluorodeoxyglucose (FDG) is a valuable tool for diagnosing and staging malignant lesions. The fusion of PET and computed tomography (CT) yields images that contain both metabolic and morphological information, which, taken together, have improved the diagnostic precision of PET in oncology. The main imaging modality for planning radiotherapy treatment is CT. However, PET-CT is an emerging modality for use in planning treatments because it allows for more accurate treatment volume definition. The use of PET-CT for treatment planning is highly complex, and protocols and standards for its use are still being developed. It seems probable that PET-CT will eventually replace current CT-based planning methods, but this will require a full understanding of the relevant technical aspects of PET-CT planning. The aim of the present document is to review these technical aspects and to provide recommendations for clinical use of this imaging modality in the radiotherapy planning process.

Sentinel node navigation surgery in early-stage esophageal cancer

The sentinel node (SN) concept has revolutionized the surgical staging of both melanoma and breast cancer over the past two decades. However, the validity of the SN hypothesis has been controversial for esophageal cancer, because SN mapping for esophageal cancer is technically complicated, and the number of early-stage esophageal cancer is very limited. Nevertheless previous studies nicely demonstrated that SN mapping may be feasible in patients with early-stage esophageal cancer. Transthoracic extended esophagectomy with three-field radical lymph node dissection has been recognized as a curative procedure for thoracic esophageal cancer in Japan. However, uniform application of this highly invasive procedure might increase the morbidity and markedly reduce the quality of life (QOL) after surgery. Although further accumulation of evidence based on multicenter clinical trials using a standard protocol is needed, SN mapping and SN navigation surgery would provide significant information to perform individualized selective lymphadenectomy which might reduce the morbidity and retain the patients' QOL. In addition, technical innovation including the development of new tracers is expected to confirm the accuracy and reliability of SN mapping in esophageal cancer.

Role of (18F) 2-fluoro-2-deoxyglucose positron emission tomography in upper gastrointestinal malignancies

The role of whole-body FDG [(¹⁸F) 2-fluoro-2-deoxyglucose] positron emission tomography (PET) scanning as an imaging modality in the management of patients with malignancy has evolved enormously over the past two decades. FDG-PET has demonstrated significant efficacy in the staging, prognostication and detection of occult metastatic disease in malignancies of the gastrointestinal tract, in addition to assessment of the response to cytotoxic chemotherapy in a more timely manner than has traditionally been possible by more conventional imaging tools. The sensitivity and specificity of FDG-PET for the detection and staging of malignancy depend not only on the site and size of the primary tumor and metastases, but also on histological cell type, reflecting underlying disparities in glucose metabolism. The metabolic response to neo-adjuvant chemotherapy or to chemo-radiotherapy in cancers of the gastro-esophageal junction or stomach has been demonstrated in several prospective studies to correlate significantly with both the histological tumor response to treatment and with consequent improvements in overall survival. This may offer a future paradigm of personalized treatment based on the PET response to chemotherapy. FDG-PET has been less successful in efforts to screen for and detect recurrent upper gastrointestinal malignancies, and in the detection of low volume metastatic peritoneal disease. Efforts to improve the accuracy of PET include the use of novel radiotracers such as (¹⁸F) FLT (3-deoxy-3-fluorothymidine) or ¹¹C-choline, or fusion PET-CT with concurrent high-resolution computed tomography. This review focuses on the role of FDG-PET scanning in staging and response assessment in malignancies of the upper gastrointestinal tract, specifically gastric, esophageal and pancreas carcinoma.

Sentinel lymph node biopsy in esophageal cancer: should it be standard of care?

INTRODUCTION

Sentinel node mapping is established in some superficial cancers but remains controversial in harder-to-access solid tumors. There are an increasing number of recent studies suggesting that isolated tumor cells have prognostic significance in predicting poor survival, in breast cancer, esophageal cancer, and others. It is for this reason that we have persevered with the sentinel lymph node concept in our esophagectomy cancer patients, and we report our results since 2008.

METHODS

Thirty-one of 32 consecutive patients underwent resection for invasive esophageal cancer along with sentinel lymph node retrieval (resection rate, 97%). Peritumoral injection of (99m)Tc antimony colloid was performed by upper endoscopy prior to the operation. A two-surgeon synchronous approach via a right thoracotomy and laparotomy was performed with a conservative lymphadenectomy. Sentinel lymph nodes were identified with a gamma probe both in and ex vivo, and sent off separately for three serial sections and immunohistochemistry with AE1/AE3.

RESULTS

The median patient age was 63.4 years (range, 45-75 years). Most patients (81%) had an adenocarcinoma, and 61% had received neoadjuvant therapy. At least one sentinel lymph node (median, 3) was identified in 29 of 31 patients (success rate, 94%). Sentinel nodes were present in more than one nodal station in 16 patients (55%). One false negative case led to a sensitivity of 90%. In 28 of 29 patients, the sentinel lymph node accurately predicted findings in non-sentinel nodes (accuracy, 96%).

CONCLUSIONS

Sentinel lymph node biopsy is both feasible and accurate in esophageal resections with conservative lymphadenectomy. It allows targeted serial sectioning and immunohistochemical studies of those nodes and should become standard of care in patients undergoing esophagectomy for esophageal cancer.

Technological advances in radiotherapy for esophageal cancer

Radiotherapy with concurrent chemotherapy and surgery represent the main treatment modalities in esophageal cancer. The goal of modern radiotherapy approaches, based on recent technological advances, is to minimize post-treatment complications by improving the gross tumor volume definition (positron emission tomography-based planning), reducing interfraction motion (image-guided radiotherapy) and intrafraction motion (respiratory-gated radiotherapy), and by better dose delivery to the precisely defined planning target volume (intensity-modulated radiotherapy and proton therapy). Reduction of radiotherapy-related toxicity is fundamental to the improvement of clinical results in esophageal cancer, although the dose escalation concept is controversial.