18F-FAMT-PET is useful for the diagnosis of lymph node metastasis in operable esophageal squamous cell carcinoma

Baseline 18F-FDG PET/CT quantitative parameters as prognostic factors in esophageal squamous cell cancer

AIM

To determine the utility of [¹⁸F]FDG PET/CT quantitative parameters as prognostic factors for the response to neoadjuvant treatment, progression-free survival (PFS) and cancer-specific survival (CSS) in patients with esophageal squamous cell carcinoma (SCC).

MATERIAL AND METHODS

Thirty patients (29 men) diagnosed with SCC were retrospectively evaluated over a 6-year interval. Metabolic parameters were determined: maximum SUV (SUVmax), mean SUV (SUVmed), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) from baseline PET/CT study. After treatment with chemotherapy and/or radiotherapy, response to treatment and patient survival were assessed. The comparison of parameters between groups of responders and non-responders was carried out using a Mann-Whitney U test ROC curves and the Kaplan-Meier method were used for analysis of prognostic factors and survival curves.

RESULTS

The average follow-up was 22.4 months, with 22 recurrence-progressions and 25 deaths. Significant differences were demonstrated between responders and non-responders with respect to tumor size, MTV and TLG. Survival analysis found significant differences for SCE and CSS depending on these three parameters.

CONCLUSION

Metabolic parameters MTV and TLG, and tumor size were prognostic factors for neoadjuvant treatment response, PFS, and CSS in patients diagnosed with SCC. Neither SUVmax nor SUVmed were predictive for any of the evaluation criteria. Results could help to personalize patient treatment.

Baseline 18F-FDG PET/CT quantitative parameters as prognostic factors in esophageal squamous cell cancer

AIM

To determine the utility of 18F-FDG PET/CT quantitative parameters as prognostic factors for the response to neoadjuvant treatment, progression-free survival (PFS) and cancer-specific survival (CSS) in patients with esophageal squamous cell carcinoma (SCC).

MATERIAL AND METHODS

Thirty patients (29 men) diagnosed with SCC were retrospectively evaluated over a 6-year interval. Metabolic parameters were determined: maximum SUV (SUVmax), mean SUV (SUVmed), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) from baseline PET/CT study. After treatment with chemotherapy and/or radiotherapy, response to treatment and patient survival were assessed. The comparison of parameters between groups of responders and non-responders was carried out using a Mann-Whitney U test. ROC curves and the Kaplan-Meier method were used for analysis of prognostic factors and survival curves.

RESULTS

The average follow-up was 22.4months, with 22 recurrence-progressions and 25 deads. Significant differences were demonstrated between responders and non-responders with respect to tumor size, MTV and TLG. Survival analysis found significant differences for SCE and CSS depending on these three parameters.

CONCLUSION

Metabolic parameters MTV and TLG, and tumor size were prognostic factors for neoadjuvant treatment response, PFS, and CSS in patients diagnosed with SCC. Neither SUVmax nor SUVmed were predictive for any of the evaluation criteria. Results could help to personalize patient treatment.

One-by-One Comparison of Lymph Nodes Between 18F-FDG Uptake and Pathological Diagnosis in Esophageal Cancer

Esophagectomy with extended lymph node (LN) dissection is a standard treatment for resectable esophageal cancer to prevent recurrence, but severe, potentially life-threatening postoperative complications are still important issues. Accurate diagnosis of LN metastases would enable the decision to dissect or leave the LNs in regions with high risk of complications. Advancements in intraoperative gamma probe and radioactivity detectors have made intraoperative navigation surgery possible using a radiotracer as a marker. ¹⁸F-FDG is one such candidate markers, and the diagnostic power of FDG through counting the radioactivity close to each LN should be elucidated.

Research progress of 18F labeled small molecule positron emission tomography (PET) imaging agents

With the development of positron emission tomography (PET) technology, a variety of PET imaging agents labeled with radionuclide ¹⁸F have been developed and widely used in the diagnosis and treatment of various clinical diseases in recent years. For example, they have showed a great value of study in the field of tumor detection, tumor treatment and evaluation of tumor therapy in a non-invasive, qualitative and quantitative way. In this review, we highlight the recent development in chemical synthesis, structure and characterization, imaging characterization, and potential applications of these ¹⁸F labeled small molecule PET imaging agents for the past five years. The development and application of ¹⁸F labeled small molecules will expand our knowledge of the function and distribution of diseases-related molecular targets and shed light on the diagnosis and treatment of various diseases including tumors.

Uptake of positron emission tomography tracers reflects the tumor immune status in esophageal squamous cell carcinoma

The relationship between the local immune status and cancer metabolism regarding ¹⁸F‐FDG and ¹⁸F‐FAMT uptake in esophageal squamous cell carcinoma (ESCC) remains unknown. The present study examined the correlations between tumor immune status, clinicopathological factors, and positron emission tomography (PET) tracer uptake in ESCC. Forty‐one ESCC patients who underwent ¹⁸F‐FDG PET and ¹⁸F‐FAMT PET before surgery were enrolled in the study. Immunohistochemistry was conducted for programmed death 1 (PD‐1), CD8, Ki‐67, CD34, GLUT1 (¹⁸F‐FDG transporter) and LAT1 (¹⁸F‐FAMT transporter). ESCC specimens with high tumoral PD‐L1 and high CD8‐positive lymphocytes were considered to have “hot tumor immune status.” High PD‐L1 expression (53.7%) was significantly associated with tumor/lymphatic/venous invasion (P = 0.028, 0.032 and 0.018), stage (P = 0.041), CD8‐positive lymphocytes (P < 0.001), GLUT1 (P < 0.001), LAT1 expression (P = 0.006), Ki‐67 labelling index (P = 0.009) and CD34‐positive vessel counts (P < 0.001). SUVmax of ¹⁸F‐FDG was significantly higher in high PD‐L1 cases than in low PD‐L1 cases (P = 0.009). SUVmax of ¹⁸F‐FAMT was significantly higher in high PD‐L1 (P < 0.001), high CD8 (P = 0.012) and hot tumor groups (P = 0.028) than in other groups. High SUVmax of ¹⁸F‐FAMT (≥4.15) was identified as the only predictor of hot tumor immune status. High PET tracer uptake was significantly associated with cancer aggressiveness and hot tumor immune status in ESCC. PET imaging may be an effective tool to predict tumor immune status in ESCC with respect to immune checkpoint inhibitor sensitivity.

Prognostic significance of middle paraesophageal lymph node metastasis in resectable esophageal squamous cell carcinoma: A STROBE-compliant retrospective study

Lymph node metastasis (LNM) of esophageal squamous cell carcinoma (ESCC) has important prognostic significance. In this study, we examined the correlations between lymph node metastatic sites and prognosis in patients with resectable ESCC.A total of 960 patients who received curative esophagectomy with systemic lymphadenectomy between 1996 and 2014 were included in the retrospective analysis. The Kaplan-Meier method and log-rank test were used to perform the survival analysis. The prognostic significance of LNM site was evaluated by Cox regression analysis.The LNM in middle paraesophageal (P < .001), subcarinal (P < .001), lower paraesophageal (P < .001), recurrent laryngeal nerve (P = .012), paratracheal (P = .014), and perigastric (P < .001) sites were associated with poor prognosis in univariate analysis. In multivariate analysis, only middle paraesophageal LNM (MPLNM, P = .017; HR, 1.33; 95%CI, 1.05-1.67) was the independent factor for worse prognosis. Additionally, patients with MPLNM had a lower 5-year survival rate (15.6%) than those with LNM at other sites. Furthermore, upper or middle tumor location and relatively late pN stage were associated with increased risk of MPLNM.Our findings suggested MPLNM could be a characteristic indicating the worst prognosis. Preoperative examinations should identify the existences of MPLNM, especially on patients with risk factors. And patients with MPLNM should be considered for more aggressive multidisciplinary therapies.

Systematic review and meta-analysis of the accuracy of 18F-FDG PET/CT for detection of regional lymph node metastasis in esophageal squamous cell carcinoma

Background

We performed a systematic review and meta-analysis to assess the accuracy of 18F-fluorodeoxyglucose positron emission tomography with computer tomography (18F-FDG PET/CT) for detection of regional lymph node metastasis in esophageal squamous cell carcinoma in per-patient and per-nodal station basis.

Methods

Electronic databases were researched for studies assessing the sensitivity and specificity of PET/CT to detect the regional lymph node metastasis published between January 2006 and December 2017 on esophageal squamous cell carcinoma. STATA software was performed to assess the sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odd ratio (DOR) and summary receiver operating characteristic (SROC) curve. The Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) and Deeks' Funnel Plot Asymmetry Test were performed to evaluate the study quality and publication bias of included studies.

Results

Nineteen studies were eligible for meta-analysis, comprising 1,089 patients with esophageal cancer who underwent 18F-FDG PET/CT before surgery. According to the content of the article, we divided the selected studies into per-patient basis group and per-nodal basis group (one of the articles was involved in both groups). For the per-nodal station basis group (12 studies, 5,681 stations), the pooled sensitivity and specificity estimates of 18F-FDG PET/CT for detecting regional lymph node metastasis were 66% [95% confidence interval (CI): 51-78%] and 96% (95% CI: 92-98%), respectively. The corresponding values on a per-patient basis group (8 studies; 506 patients) were 65% (95% CI: 49-78%) and 81% (95% CI: 69-89%) in sensitivity and specificity, respectively.

Conclusions

Overall, 18F-FDG PET/CT have a moderate to low sensitivity and a high to moderate specificity for detection of regional nodal metastasis in esophageal cancer. Therefore, since the false rate is considerable, extending the extent of lymph node dissection or radiotherapy target volume is necessary after diagnosis of regional nodal metastasis by 18F-FDG PET/CT.

18F-FAMT-PET Is Useful for Judging Clinical Complete Response in Advanced Esophageal Cancer Patients Who Have Received Definitive Chemoradiotherapy

We developed l-[3-18F]-α-methyltyrosine (18F-FAMT) as an amino acid tracer for positron emission tomography (PET) imaging. In esophageal cancer, the specificity of 18F-FAMT PET was significantly higher than that of fluoro-2-deoxy-d-glucose (18F-FDG) PET and computed tomography (CT) in the evaluation of individual lymph node groups. Definitive chemoradiotherapy (CRT) has been considered a potentially curative treatment for locoregional esophageal cancer and may achieve the same survival benefits as surgical resection. Clinical evaluation of complete response (CR) is important using several modalities. We evaluated 6 patients who had been diagnosed with clinical CR by FAMT-PET following definitive CRT for esophageal squamous cell carcinoma between June 2008 and July 2012. Treatment evaluation of 18F-FAMT was performed following CRT and approximately 1 month later. In primary tumors, 66.7% of patients (4/6) showed FDG uptake following CRT, whereas that of FAMT was 33.3% (2/6). In lymph node metastases, 50% of patients (3/6) showed FDG uptake following CRT, whereas that of FAMT was 0% (0/6). In the present study, FAMT-PET following CRT was a useful modality to predict clinical CR in esophageal cancer. There is a limit to judging clinical CR by CT or FDG-PET following CRT, because radiation-related esophagitis and reactive mediastinal lymphadenopathy by FDG and wall thickness by CT still remain 1 month following CRT. FAMT-PET is the most useful modality at the present time.

Nrf2 promotes oesophageal cancer cell proliferation via metabolic reprogramming and detoxification of reactive oxygen species

Cancer cells consume a large amount of energy and maintain high levels of anabolism to promote cell proliferation via metabolic reprogramming. Nuclear factor erythroid 2-related factor 2 (Nrf2; NFE2L2) is a master transcription regulator of stress responses and promotes metabolic reprogramming to support cell proliferation in various types of cancer. As oesophageal cancer is one of the most aggressive gastrointestinal cancers, we aimed to clarify the effect of Nrf2 on metabolic reprogramming in oesophageal cancer. The relationship between Nrf2 expression and clinical outcome was evaluated using a database comprising 201 oesophageal cancers. Using in vitro assays and metabolome analysis, we examined the mechanism by which Nrf2 affects malignant phenotype. High-level immunohistochemical expression of Nrf2 was significantly associated with poor recurrence-free survival (HR = 2.67, p = 0.0004) and overall survival (HR = 2.90, p < 0.0001) in oesophageal cancer patients. In an in vitro assay with siRNA in TE-11 cells, which showed high Nrf2 expression, Nrf2 depletion significantly decreased cell growth and enhanced G1 cell cycle arrest and apoptosis. In addition, reactive oxygen species (ROS) were not removed by detoxification via the Nrf2 pathway, with concomitant induction of the p38 mitogen-activated protein kinase pathway. The metabolome analysis showed that Nrf2 strongly promoted metabolic reprogramming to glutathione metabolism, which synthesizes the essential fuels for cancer progression. Furthermore, metabolome analysis using oesophageal cancer specimens confirmed that samples displaying high Nrf2 expression promoted glutathione synthesis. Metabolic reprogramming to glutathione metabolism, and ROS detoxification by activation of Nrf2, enhanced cancer progression and led to a poor clinical outcome in oesophageal cancer patients. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

PET/Computed Tomography Scanning and Precision Medicine: Esophageal Cancer

Esophageal cancer commonly has a poor prognosis, which requires an accurate diagnosis and early treatment to improve outcome. Other modalities for staging, such as endoscopic ultrasound imaging and computed tomography (CT) scans, have a role in diagnosis and staging. However, PET with fluorine-18 fluoro-2-deoxy-d-glucose/CT (FDG PET/CT) scanning allows for improved detection of distant metastatic disease and can help to prevent unnecessary interventions that would increase morbidity. FDG PET/CT scanning is valuable in the neoadjuvant chemotherapy assessment and predicting survival outcomes subsequent to surgery. FDG PET/CT scanning detects recurrent disease and metastases in follow-up.

Lysine-specific demethylase-1 contributes to malignant behavior by regulation of invasive activity and metabolic shift in esophageal cancer

Lysine-specific demethylase-1 (LSD1) removes the methyl groups from mono- and di-methylated lysine 4 of histone H3. Previous studies have linked LSD1 to malignancy in several human tumors, and LSD1 is considered to epigenetically regulate the energy metabolism genes in adipocytes and hepatocellular carcinoma. This study investigates the function of LSD1 in the invasive activity and the metabolism of esophageal cancer cells. We investigated whether LSD1 immunohistochemical expression levels are related to clinical and pathological features, including the maximum standard uptake value in fluorodeoxyglucose positron emission tomography assay. The influence of LSD1 on cell proliferation, invasion and glucose uptake was evaluated in vitro by using specific small interfering RNA for LSD1, and an LSD1 inhibitor. We also evaluated two major energy pathways (glycolytic pathway and mitochondrial respiration) by measuring the extracellular acidification rate (ECAR) and the oxygen consumption rate (OCR) with an extracellular flux analyzer. High LSD1 immunohistochemical expression was significantly associated with high tumor stage, lymphovascular invasion, poor prognosis, and high maximum standard uptake value in esophageal cancer patients. In the in vitro analysis, LSD1 knockdown significantly suppressed the invasive activity and glucose uptake of cancerous cells, reduced their ECAR and increased their OCR and OCR/ECAR. LSD1 may contribute to malignant behavior by regulating the invasive activity and metabolism, activating the glycolytic pathway and inhibiting the mitochondrial respiration of esophageal cancer cells. The results support LSD1 as a potential therapeutic target.

State-of-the-art molecular imaging in esophageal cancer management: implications for diagnosis, prognosis, and treatment

Molecular imaging techniques are increasingly being used in addition to standard imaging methods such as endoscopic ultrasound (EUS) and computed tomography (CT) for many cancers including those of the esophagus. In this review, we will discuss the utility of the most widely used molecular imaging technique, (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET). (18)F-FDG PET has a variety of potential applications ranging from improving staging accuracy at the time of initial diagnosis to assisting in radiation target volume delineation. Furthermore, (18)F-FDG PET can be used to evaluate treatment response after completion of neoadjuvant therapy or potentially during neoadjuvant therapy. Finally, we will also discuss other novel molecular imaging techniques that have potential to further improve cancer care.

Biological significance of fluorine-18-α-methyltyrosine (FAMT) uptake on PET in patients with oesophageal cancer

PURPOSE

(18)F-FAMT as an amino-acid tracer for positron emission tomography (PET) is useful for detecting human neoplasms. (18)F-FAMT is accumulated in tumour cells solely via L-type amino-acid transporter 1 (LAT1). This study was conducted to investigate the biological significance of (18)F-FAMT uptake in patients with oesophageal cancer.

METHODS

From April 2008 to December 2011, 42 patients with oesophageal cancer underwent both (18)F-FAMT PET/CT and (18)F-FDG PET/CT before surgical treatment. The immunohistochemical analysis of LAT1, CD98, Ki-67, CD34, p53, p-Akt and p-mTOR was performed on the primary lesions. In vitro experiments were performed to examine the mechanism of (18)F-FAMT uptake.

RESULTS

High uptake of (18)F-FAMT was significantly associated with advanced stage, lymph node metastasis and the expression of LAT1, CD98, Ki-67 and CD34. LAT1 expression yielded a statistically significant correlation with CD98 expression, cell proliferation, angiogenesis and glucose metabolism. In vitro experiments revealed that (18)F-FAMT was specifically transported by LAT1.

CONCLUSIONS

The uptake of (18)F-FAMT within tumour cells is determined by the LAT1 expression and correlated with cell proliferation and angiogenesis in oesophageal cancer. The present experiments also confirmed the presence of LAT1 as an underlying mechanism of (18)F-FAMT accumulation.

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.

High expression of glucose transporter 1 on primary lesions of esophageal squamous cell carcinoma is associated with hematogenous recurrence

PURPOSE

Glucose transporter type 1 (Glut1) plays a crucial role in cancer-specific metabolism to adapt to the rapid growth and tumor microenvironment in diverse malignant tumors. This study examined the clinical, pathological, and prognostic features of Glut1 expression on primary lesions of esophageal squamous cell carcinoma.

METHODS

Immunohistochemical staining of Glut1 and CD34 was performed using paraffin-embedded sections of tissues obtained from 145 resectable esophageal squamous cell carcinoma patients without preoperative treatment. Microvessel density was calculated from CD34 staining.

RESULTS

Glut1 positivity was observed in 41 patients (28.2 %) and associated with depth of invasion [odds ratio (OR) 2.984; 95 % confidence interval (CI) 1.208-7.371; P = 0.018] and vascular invasion (OR 2.771; 95 % CI 1.118-6.871; P = 0.028) in multivariate analysis. Glut1 positivity was a significant disadvantage to both relapse-free survival [hazard ratio (HR) 2.021; 95 % CI 1.100-3.712; P = 0.023] and esophageal cancer-specific survival (HR 2.223; 95 % CI 1.121-4.411; P = 0.022) in univariate Cox hazard analysis, but was not independently associated with relapse-free survival or cancer-specific survival in multivariate analysis. The relationship between Glut1 expression and first relapse site was investigated. Glut1 positivity was not associated with lymph node recurrence (HR 1.009; 95 % CI 0.402-2.530; P = 0.985) but was significantly associated with hematogenous recurrence (HR 3.701; 95 % CI 1.655-8.273; P = 0.001) in univariate Cox hazard analysis. Microvessel density was calculated to evaluate angiogenesis, and it was observed that Glut1 positivity was significantly associated with high microvessel density (P < 0.001).

CONCLUSIONS

Glut1 expression was associated with hematogenous recurrence. The findings provide evidence of the significance of Glut1 expression as a biomarker.

Synthesis and biological evaluation of O-[3-18F-fluoropropyl]-α-methyl tyrosine in mesothelioma-bearing rodents

Radiolabeled tyrosine analogs enter cancer cells via upregulated amino acid transporter system and have been shown to be superior to ¹⁸F-fluoro-2-deoxy-D-glucose (¹⁸F-FDG) in differential diagnosis in cancers. In this study, we synthesized O-[3-¹⁹F-fluoropropyl]-α-methyl tyrosine (¹⁹F-FPAMT) and used manual and automated methods to synthesize O-[3-¹⁸F-fluoropropyl]-α-methyl tyrosine (¹⁸F-FPAMT) in three steps: nucleophilic substitution, deprotection of butoxycarbonyl, and deesterification. Manual and automated synthesis methods produced ¹⁸F-FPAMT with a radiochemical purity >96%. The decay-corrected yield of ¹⁸F-FPAMT by manual synthesis was 34% at end-of-synthesis (88 min). The decay-corrected yield of ¹⁸F-FPAMT by automated synthesis was 15% at end-of-synthesis (110 min). ¹⁸F-FDG and ¹⁸F-FPAMT were used for in vitro and in vivo studies to evaluate the feasibility of ¹⁸F-FPAMT for imaging rat mesothelioma (IL-45). In vitro studies comparing ¹⁸F-FPAMT with ¹⁸F-FDG revealed that ¹⁸F-FDG had higher uptake than that of ¹⁸F-FPAMT, and the uptake ratio of ¹⁸F-FPAMT reached the plateau after being incubated for 60 min. Biodistribution studies revealed that the accumulation of ¹⁸F-FPAMT in the heart, lungs, thyroid, spleen, and brain was significantly lower than that of ¹⁸F-FDG. There was poor bone uptake in ¹⁸F-FPAMT for up to 3 hrs suggesting its in vivo stability. The imaging studies showed good visualization of tumors with ¹⁸F-FPAMT. Together, these results suggest that ¹⁸F-FPAMT can be successfully synthesized and has great potential in mesothelioma imaging.

Diagnostic usefulness of ¹⁸F-FAMT PET and L-type amino acid transporter 1 (LAT1) expression in oral squamous cell carcinoma

PURPOSE

L-[3-(18)F]-α-Methyltyrosine ((18)F-FAMT) was developed as an amino acid tracer for PET imaging to provide better specificity than 2-[(18)F]fluoro-2-deoxy-D-glucose ((18)F-FDG) PET for cancer diagnosis. We investigated the diagnostic usefulness of (18)F-FAMT in oral squamous cell carcinoma (OSCC). The correlation between tumour uptake of (18)F-FAMT and L-type amino acid transporter 1 (LAT1) expression was determined.

METHODS

The study group comprised 68 OSCC patients who underwent both (18)F-FAMT and (18)F-FDG PET. Resected tumour sections were stained by immunohistochemistry for LAT1, CD98 and Ki-67, and microvessel density was determined in terms of CD34 and p53 expression.

RESULTS

The sensitivity of primary tumour detection by (18)F-FAMT and (18)F-FDG PET was 98 % and 100 %, respectively. The sensitivity, specificity and accuracy of (18)F-FAMT PET for detecting malignant lymph nodes were 68 %, 99 % and 97 %, respectively, and equivalent values for (18)F-FDG PET were 84 %, 94 % and 94 %, respectively. The specificity and accuracy of (18)F-FAMT were significantly higher than those of (18)F-FDG. The uptake of (18)F-FAMT was significantly correlated with LAT1 expression, cell proliferation and advanced stage. The expression of LAT1 in OSCC cells was closely correlated with CD98 levels, cell proliferation and angiogenesis.

CONCLUSION

(18)F-FAMT PET showed higher specificity for detecting malignant lesions than (18)F-FDG PET. The uptake of (18)F-FAMT by OSCC cells can be determined by the presence of LAT1 expression and tumour cell proliferation.

Meta-analysis of 18FDG PET-CT for nodal staging in patients with esophageal cancer

BACKGROUND

We aimed to evaluate the value of (18)FDG PET-CT for detection of regional nodal metastasis in patients with esophageal cancer before surgery.

METHODS

A computer search about PET-CT original articles was conducted from January 2000 to December 2012. The reference standard was histopathologic analysis. Two reviewers independently searched articles and extracted data. Sensitivity, specificity, diagnostic odds ratio, and likelihood ratio were pooled for PET-CT using bivariate models. Summary receiver operating characteristic (SROC) curves were also used to summarize overall test performance.

RESULTS

Across all seven studies on a per-station analysis (2232 stations), the pooled sensitivity and specificity with 95% confidence interval for PET-CT were 0.62 (0.40-0.79) and 0.96 (0.93-0.98). Across all 6 studies on a per-patient analysis (245 patients), corresponding values for PET-CT were 0.55 (0.34-0.74) and 0.76 (0.66-0.83).

CONCLUSIONS

(18)FDG PET-CT had lower sensitivity and accuracy for detection of regional nodal metastasis in patients with esophageal cancer before surgery.

The significance of lymph node status as a prognostic factor for esophageal cancer

The revision of the TNM Classification of Malignant Tumors, 7th Edition, suggests the lymph node (LN) status to be the most significant risk factor in esophageal cancer. This article reviews the current status of LNs as indicators of prognosis. The significance of the number of metastatic LNs, the number of resected LNs, and a novel index, the "LN ratio" (metastatic LNs/removed LNs) in patients with esophageal cancer, were reviewed. The number of metastatic LNs independently predicted the prognosis of both overall survival and relapse-free survival. The number of positive LNs was also the best predictive marker of survival. Furthermore, overall survival significantly depended on the number of surgically removed LNs, and the LN ratio closely correlated with survival. The LN status is considered to be the most significant information that can be used to predict the prognosis. However, there are many issues that still need to be resolved. Better knowledge of the N-status is therefore needed to effectively utilize this information. Further research should focus on the N-status of patients with esophageal cancer.

Paget's disease of bone resembling bone metastasis from gastric cancer

A 74-year-old man had an endoscopic type 0'-IIc tumor in the upper gastric body on the greater curvature and biopsy showed the tumor to be a well-differentiated adenocarcinoma (Group 5). He was referred to us for endoscopic submucosal dissection (ESD). Endoscopy revealed fold convergency, fold swelling, and fusion of the fold, indicating tumor invasion into the submucosa, which was outside the indications for ESD. In addition, there was an increase of serum bone-type alkaline phosphatase (ALP-III and ALP-IV) and urinary cross-linked N-terminal telopeptide of type I collagen (a bone metabolism marker), while (18)F-fluorodeoxyglucose positron emission tomography showed increased uptake in the left pelvis and Th10, suggesting bone metastases. We first diagnosed gastric cancer with bone metastases; however, the symptoms suggested pathological bone fracture and no bone pain. Therefore, a computed tomography-guided aspiration bone biopsy was performed to exclude the possibility of Paget's disease of bone. Biopsy specimens revealed no tumor and a mosaic pattern. No increased uptake of (18)F-FAMT (L-[3-(18)F] α-methyltyrosine) supported a diagnosis of no bone metastases from gastric cancer. We finally diagnosed gastric cancer accompanied by Paget's disease of bone and performed a laparoscopy-assisted proximal gastrectomy. The pathological diagnosis was U less 0-IIb, and U post 0-IIc ypT1a (M) N0H0P0M0 yp stage IA. In gastric cancer patients with suspected bone metastasis, we also need to consider Paget's disease of bone.

Preparation and biological evaluation of 3-[(76)Br]bromo-α-methyl-L-tyrosine, a novel tyrosine analog for positron emission tomography imaging of tumors

INTRODUCTION

3-[(18)F]fluoro-α-methyl-l-tyrosine ([(18)F]FAMT) is a useful amino acid tracer for positron emission tomography (PET) imaging of malignant tumors. FAMT analogs labeled with (76)Br, a positron emitter with a long half-life (t(1/2)=16.1 h), could potentially be widely used as amino acid tracers for tumor imaging. In this study, 3-[(76)Br]bromo-α-methyl-l-tyrosine ([(76)Br]BAMT) was designed, and its usefulness was evaluated as a novel PET tracer for imaging malignant tumors.

METHODS

In this study, both [(76)Br]BAMT and [(77)Br]BAMT were prepared. The in vitro and in vivo stability of [(77)Br]BAMT was evaluated by HPLC analysis. Cellular uptake and retention of [(77)Br]BAMT and [(18)F]FAMT were evaluated using LS180 colon adenocarcinoma cells. Biodistribution studies were performed in normal mice and in LS180 tumor-bearing mice, and the tumors were imaged with a small-animal PET scanner.

RESULTS

[(77)Br]BAMT was stable in vitro but was catabolized after administration in mice. Cellular accumulation and retention of [(77)Br]BAMT were significantly higher than those of [(18)F]FAMT. In biodistribution studies, the tumor accumulation of [(77)Br]BAMT was higher than that of [(18)F]FAMT. However, some level of debromination was seen, which caused more retention of radioactivity in the blood and organs than was seen with [(18)F]FAMT. PET imaging with [(76)Br]BAMT enabled clear visualization of the tumor, and the whole-body image using [(76)Br]BAMT was similar to that using [(18)F]FAMT.

CONCLUSIONS

[(77)Br]BAMT showed high levels of tumor accumulation, and [(76)Br]BAMT enabled clear visualization of the tumor by PET imaging. Although an improvement in stability is still needed, (76)Br-labeled FAMT analogs could potentially serve as PET tracers for the imaging of malignant tumors.