Adenoviral gene therapy in gastric cancer: A review

High Expression of COL10A1 Is an Independent Predictive Poor Prognostic Biomarker and Associated with Immune Infiltration in Advanced Gastric Cancer Microenvironment

Medical technology has become more and more sophisticated recently, which, however, fails to contribute to a better prognosis for patients suffering advanced gastric cancer (GC). Hence, new biomarkers specific to GC diagnosis and prognosis shall be identified urgently. This study screened differentially expressed genes (DEGs) between 375 GC samples and 32 paracancer tissue samples from TCGA datasets. The expression of Collagen type X alpha 1 (COL10A1) in GC was analyzed. The chi-square test assisted in analyzing the relevance of COL10A1 to the clinicopathologic characteristics. The Kaplan-Meier method helped to assess the survival curves and log-rank tests assisted in the examination of the differences. The Cox proportional hazard regression model served for analyzing the risk factors for GC. Then, we developed a nomogram that contained the COL10A1 expression and clinical information. Finally, how COL10A1 expression was associated with the immune infiltration was also evaluated. In this study, 7179 upregulated and 3771 downregulated genes were identified. Among them, COL10A1 expression was distinctly increased in GC specimens compared with nontumor specimens. High COL10A1 expression exhibited an obvious relation to tumor T and pathologic stage. ROC assays confirmed the diagnostic value of COL10A1 expression in screening GC samples from normal samples. Survival data displayed that patients with high COL10A1 expression exhibited a shorter OS and DSS than those with low COL10A1 expression. We obtained a predictive nomogram, which could better predict the COL10A1 expression by virtue of discrimination and calibration. The prognostic value of COL10A1 expression was further confirmed in GSE84426 datasets. Immune assays revealed that COL10A1 expression was associated with tumor-filtrating immune cells, like CD8 T cells, cytotoxic cells, DC, eosinophils, iDC, macrophages, mast cells, NK CD56dim cells, NK cells, pDC, T helper cells, Tem, Th1 cells, Th17 cells, and Treg. Overall, we firstly proved that COL10A1 may be a novel and valuable prognostic and diagnostic factor for GC patients. In addition, COL10A1 has potential to be an immune indicator in GC.

Apoptosis-Inducing TNF Superfamily Ligands for Cancer Therapy

Cancer is a complex disease with apoptosis evasion as one of its hallmarks; therefore, apoptosis induction in transformed cells seems a promising approach as a cancer treatment. TNF apoptosis-inducing ligands, which are naturally present in the body and possess tumoricidal activity, are attractive candidates. The most studied proteins are TNF-α, FasL, and TNF-related apoptosis-inducing ligand (TRAIL). Over the years, different recombinant TNF family-derived apoptosis-inducing ligands and agonists have been designed. Their stability, specificity, and half-life have been improved because most of the TNF ligands have the disadvantages of having a short half-life and affinity to more than one receptor. Here, we review the outlook on apoptosis-inducing ligands as cancer treatments in diverse preclinical and clinical stages and summarize strategies of overcoming their natural limitations to improve their effectiveness.

Recombinant virus expressing hIFN-λ1 (rL-hIFN-λ1) has important effects on endoplasmic reticulum stress, autophagy and apoptosis in small cell lung cancer

BACKGROUND

Small cell lung cancer (SCLC) is an aggressive tumor with a poor prognosis. Human IFN-λ1 (IL-29), belonging to the type III IFN family, captured increasing attention recently due to its crucial role in developing tumors. Recent studies have revealed that the recombinant Newcastle Disease Virus (NDV) expressing human IFN-λ1 (rL-hIFN-λ1) plays a critical role in the development of tumors. However, the role of rL-hIFN-λ1 in SCLC is still unknown.

METHODS

We determined the concentration of the virus intervention, followed by successfully infection in virus. We also investigated the effects of rL-hIFN-λ1 on endoplasmic reticulum stress (ERS), apoptosis and autophagy in H446 cells, and explored the interaction among the three.

RESULTS

We found that the ERS, autophagy and apoptosis related proteins were significantly upregulated after infected with rL-hIFN-λ1 or NDV. In addition, both 4-phenylbutyric acid (4-PBA) or 3-Methyladenine (3-MA) could downregulate the expression of related proteins which increased by rL-hIFN-λ1. Furthermore, we found that both B-cell lymphoma-2 (BCL-2) knockdown or Rapamycin (Rapa) could increase ERS, autophagy and apoptosis.

CONCLUSIONS

Our findings suggest that rL-hIFN-λ1 can induce ERS, autophagy and apoptosis in SCLC H446 cells, particularly, autophagy plays an important role during this process. Furthermore, rL-hIFN-λ1 might provide a potential biological treatment target for lung cancer treatment.

Reduction of gastric cancer proliferation and invasion by miR-15a mediated suppression of Bmi-1 translation

B-cell specific moloney leukemia virus insertion site 1 (Bmi-1) gene plays important roles in gastric cancer, but the epigenetic regulatory mechanism by microRNA (miRNA) and the functional significance of Bmi-1 inhibition in gastric cancer remains elusive. In this study, we systematically investigated the functional roles of miRNA mediated Bmi-1 suppression in gastric cancer. Our results show that the expression of miR-15a is significantly reduced in gastric cancer and the protein expression levels of Bmi-1 are inversely correlated with miR-15a (P = 0.034) in gastric cancer patient samples. Functional studies revealed that ectopic expression of miR-15a decreased Bmi-1 in gastric cancer cell lines with reduced proliferation and tumor invasion. High levels of Bmi-1 in gastric cancer patients are significantly associated with better overall survival (P = 0.024) based on the Kaplan-Meier survival analysis.

Genetically engineered Newcastle disease virus expressing human interferon-λ1 induces apoptosis in gastric adenocarcinoma cells and modulates the Th1/Th2 immune response

Interferon-λ1 (IFN-λ1), a recently discovered cytokine of the type III IFN family, was found to be a therapeutic alternative to type I IFN in terms of tumors. Using reverse genetics technique, we generated a recombinant Newcastle disease virus (NDV) LaSota strains named as human IFN‑λ1 recombinant adenovirus (rL-hIFN-λ1) containing human IFN-λ1 gene and further evaluated the expressing of IFN-λ1 in human gastric adenocarcinoma cell line SGC-7901 after infected with rL-hIFN-λ1 by using western blot analysis, RT-PCR and immunofluorescence analyses. IFN-λl specific receptor IFNLR1 was detected on several gastric tumor cell lines including SGC-7901 and AGS and on PBMCs.The expression of the IFN-λ1 proteins reached a high level detected in the supernatant harvested 24 h after the infection of tumor cells. The proliferation changes of SGC infected with rL-hIFN-λ1 was significantly inhibited compared with NDV-infected group. Apoptosis was significantly induced by rL-hIFN-λ1 in gastric cancer cells compared with NDV virus tested by TUNEL assay, western blot analysis and Annexin V flow cytometry. Due to the high dose of IFN-λ1 expressed by the rL-hIFN-λ1-infected tumor cells, the immune study showed that rL-hIFN-λ1 increased IFN-γ production [the T helper cell subtype 1 (Th1) response] and inhibited interleukin (IL)-13 production [the T helper cell subtype 2 (Th2) response] to change the Th1/Th2 response of tumor microenvironment which inhibited tumor growth. This study aims at building recombinant NDV rL-hIFN-λ1 as an efficient antitumor agent.

Synergistic nanomedicine by combined gene and photothermal therapy

To date, various nanomaterials with the ability for gene delivery or photothermal effect have been developed in the field of biomedicine. The therapeutic potential of these nanomaterials has raised considerable interests in their use in potential next-generation strategies for effective anticancer therapy. In particular, the advancement of novel nanomedicines utilizing both therapeutic strategies of gene delivery and photothermal effect has generated much optimism regarding the imminent development of effective and successful cancer treatments. In this review, we discuss current research progress with regard to combined gene and photothermal therapy. This review focuses on synergistic therapeutic systems combining gene regulation and photothermal ablation as well as logically designed nano-carriers aimed at enhancing the delivery efficiency of therapeutic genes using the photothermal effect. The examples detailed in this review provide insight to further our understanding of combinatorial gene and photothermal therapy, thus paving the way for the design of promising nanomedicines.

Fluorine-18-fluorodeoxyglucose positron emission tomography to evaluate recurrent gastric cancer after surgical resection: a systematic review and meta-analysis

We aimed to explore the diagnostic accuracy of (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) for detection of gastric cancer recurrence after surgical resection through a systematic review and meta-analysis. "PubMed", EMBASE, Web of Knowledge and Springer, from the beginning of 2002 to Feb 2015, were searched for studies evaluating the diagnostic performance of 18F-FDG PET in detecting recurrent gastric cancer. We calculated sensitivities, specificities, diagnostic odds ratios and likelihood ratios, and constructed summary receiver operating characteristic curves. Fourteen studies (828 patients) were included. On a per-patient basis, the forest plots showed that the pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio and diagnostic odds ratio of (18)F-FDG PET or PET/CT were 0.85 [95 % confidence interval (CI) 0.75-0.92], 0.78 (95 % CI 0.72-0.84), 3.9 (95 % CI 2.9-5.4), 0.19 (95 % CI 0.11-0.34), and 21 (95 % CI 9-47), respectively. On a per-lesion basis, the pooled sensitivity was 0.75 (95 % CI 0.61-0.86). The area under the SROC curve of PET/CT on the basis of per-patient was 0.86. (18)F-FDG PET had great value in the detection of gastric cancer recurrence after surgical resection. The sensitivities of (18)F-FDG PET were 85 and 75 %, respectively, on per-patient basis and on per-lesion basis.

Recombinant adenovirus expressing hIFN-λ1 inhibits gastric adenocarcinoma cell line SGC-7901 proliferation

The aim of the present study is to investigate the effect of a recombinant plasmid adenovirus (pAd) expressing human interferon-λ1 (hIFN-λ1) on the proliferation of the gastric adenocarcinoma cell line SGC-7901. For this purpose, human gastric adenocarcinoma SGC-7901 cells were infected with recombinant pAd-hIFN-λ1, pAd-LacZ and phosphate-buffered saline (PBS), respectively, and the subsequent effects on the proliferation of the infected cells were compared. Cell proliferation was evaluated by MTT assay, while mRNA and protein expression of hIFN-λ1 were detected by reverse transcription-polymerase chain reaction analysis and immunofluorescence assay, respectively. In addition, terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling assay and flow cytometry were conducted to analyze the rate of cell apoptosis. The results indicated that the proliferation of gastric adenocarcinoma SGC-7901 cells was significantly inhibited by pAd-hIFN-λ1. Furthermore, the apoptosis rate and the mRNA and protein expression levels of hIFN-λ1 were higher in pAd-hIFN-λ1-transfected cells, compared with the pAd-LacZ and PBS control groups. In conclusion, recombinant pAd-hIFN-λ1 induced the expression of hIFN-λ1 in gastric adenocarcinoma SGC-7901 cells, and significantly inhibited cell proliferation by promoting apoptosis in these cancer cells.

Radiolabeling and evaluation of (64)Cu-DOTA-F56 peptide targeting vascular endothelial growth factor receptor 1 in the molecular imaging of gastric cancer

Noninvasive imaging of vascular endothelial growth factor receptor 1 (VEGFR1) remains a great challenge in early diagnosis of gastric cancer. Here we reported the synthesis, radiolabeling, and evaluation of a novel (64)Cu-radiolabeled peptide for noninvasive positron emission tomography (PET) imaging of VEGFR1 positive gastric cancer. The binding of modified peptide WHSDMEWWYLLG (termed as F56) to VEGER-1 expressed in gastric cancer cell BCG823 has been confirmed by immune-fluorescence overlap. DOTA-F56 was designed and prepared by solid-phase synthesis and folded in vitro. (64)Cu-DOTA-F56 was synthesized in high radiochemical yield and high specific activity (S.A. up to 255.6 GBq/mmol). It has excellent in vitro stability. Micro-PET imaging of (64)Cu-DOTA-F56 identifies tumor in BCG823 tumor-bearing mice, while that of (18)F-FDG does not. Immunohistochemical analysis of excised BCG823 xenograft showed colocalization between the PET images and the staining of VEGFR1. These results demonstrated that (64)Cu-DOTA-F56 peptide has potential as a noninvasive imaging agent in VEGFR1 positive tumors.

MicroRNA‑34a attenuates the proliferation, invasion and metastasis of gastric cancer cells via downregulation of MET

Proliferation, invasion and metastasis are key features of gastric cancer, contributing to high mortality rates in patients with gastric cancer worldwide. As a direct target of p53, the functions of microRNA (miR)‑34a are important, but controversial, in the progression of gastric cancer. In the present study, the clinical importance of miR‑34a in GC specimens (n=40) were investigated and were confirmed in an independent cohort from The Cancer Genome Atlas (TCGA; n=352). The prognostic value of miR‑34a was analyzed using a Kaplan‑Meier survival curve in the TCGA cohort, in combination with complete follow‑up data (n=157). The level of miR‑34a was detected in the human gastric cancer cell line and normal gastric epithelial cell line. The effect of miR‑34a on proliferation and invasion were evaluated using Cell Counting Kit 8, colony formation and cell invasion assays. The molecular basis of miR‑34a was determined by bioinformatics prediction. The correlation between miR‑34a and MET was assessed using reverse transcription‑quantitative polymerase chain reaction and western blot analyses. The results indicated that miR‑34a was downregulated in the gastric cancer tissues, compared with the normal gastric tissues (P<0.01). miR‑34a was negatively correlated with the depth of invasion and lymph node metastasis of gastric cancer (P<0.01). In the TCGA cohort, the levels of miR‑34a were lower in T3 and T4 tumor stages, compared with the level in the T1 stage, and low levels of miR‑34a predicted significantly longer survival rates in patients with GC (P<0.05). miR‑34a also attenuated the proliferation ability, and inhibited the colony formation and cell invasion abilities of the cells (P<0.01). A negative correlation was observed between miR‑34a and MET in gastric cancer (P<0.01; r=‑0.9526), and >60% of cases exhibited consistent expression of miR‑34a and MET in gastric cancer (P<0.01). In conclusion, miR‑34a was associated with the clinicopathological features of gastric cancer and was a valuable predictor of patient prognosis. miR‑34a acted as a tumor suppressor to inhibit gastric cancer proliferation and invasion via the downregulation of MET.

Autophagy is involved in recombinant Newcastle disease virus (rL-RVG)-induced cell death of stomach adenocarcinoma cells in vitro

Oncolytic viruses can kill malignant cells while sparing normal cells. Multiple pathways are involved in this action. The antitumor effects of viral infection on SGC-7901 and AGS cells were investigated. We measured endoplasmic reticulum stress and autophagy caused by the recombinant avirulent Newcastle disease virus (NDV) LaSota strain expressing the rabies virus glycoprotein (rL-RVG) and the NDV wild-type strain. The dose-response curves were analyzed using the MTT assay. The expression of RVG was detected by western blotting, RT-PCR and immunofluorescence analyses. Cell death and autophagy were observed using transmission electron microscopy, TUNEL and western blotting. Endoplasmic reticulum stress and the mitochondrial transmembrane potential were detected by western blotting and immunofluorescence, respectively. Immunofluorescence, western blot and RT-PCR analyses indicated that RVG gene and protein were expressed in SGC-7901 and AGS cells infected by rL-RVG. MTT and TUNEL analyses showed that the growth of SGC-7901 and AGS cells in the rL-RVG-infected group was significantly inhibited compared with the wild-type NDV-infected group (p<0.05). Western blot analysis indicated that rL-RVG and NDV induced increases in apoptosis, endoplasmic reticulum stress, and autophagy in the SGC-7901 and AGS cells. However, apoptosis and autophagy decreased in these cells after the application of the autophagy pathway inhibitor 3-MA or ATG-5-specific siRNA. Immunofluorescence analysis showed that the mitochondrial membrane potential collapsed. Taken together, these results indicate that the rL-RVG virus group is much more powerful compared with the NDV-infected group (p<0.05). rL-RVG and NDV are potent antitumor agents that induce autophagy.

18FDG PET-CT for detecting gastric cancer recurrence after surgical resection: a meta-analysis

BACKGROUND

We performed a meta-analysis to evaluate the value of (18)FDG PET-CT for the detection of gastric cancer recurrence after surgical resection.

METHODS

A systematic literature search was performed in the MEDLINE and EMBASE databases. We calculated the sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio for (18)FDG PET-CT. We also constructed summary receiver operating characteristic curves for (18)FDG PET-CT.

RESULTS

Eight studies (500 patients) were included. The sensitivity, specificity, positive likelihood ratio and negative likelihood ratio of (18)FDG PET-CT were 0.86 (95% confidence interval [CI] = 0.71-0.94), 0.88 (95% CI = 0.75-0.94), 17.0 (95% CI = 3.5-14.0), and 0.16 (95% CI = 0.07-0.34), respectively. Overall weighted area under the curve was 0.93 (95% CI = 0.91-0.95).

CONCLUSIONS

(18)FDG PET-CT has moderate sensitivity and specificity for detection of gastric cancer recurrence after surgical resection.

TNF-α expression in the UCB-MSCs as stable source inhibits gastric cancers growth in nude mice

Mesenchymal stem cells (MSCs) are potentially vehicles for therapy of malignant diseases. In our study, we investigated whether UCB-MSCs are capable to carry TNF-α to target tumor cells in vivo. The human gastric cancer cells SGC-7901 were subcutaneously injected into the abdomen near groins of 15 nude mice to establish experiment tumor models. MSC-TNF-α demonstrated a strong suppressive effect on the tumor growth compared with MSC and NaCl. Thus, MSC-TNF-α can obviously inhibit Gastric cancers growth in nude mice, indicating that UCB-MSCs may have the potential to become a prevention approach against gastric cancer.

Resistance of canine lymphoma cells to adenoviral infection due to reduced cell surface RGD binding integrins

Recombinant adenovirus vectors (Ad) have been recognized as effective in vivo gene delivery vehicles and utilized as gene therapy agents for a number of cancers. The elucidation of viral entry mechanisms has allowed the development of recombinant vectors that exploit existing cell surface receptors to achieve entry into the cell. B lymphocytes are normally resistant to infection by adenovirus 5, likely due to the lack of the Coxsackie and Adenovirus receptor (CAR). Using reverse-transcriptase PCR and flow cytometry, the CD40 receptor has been shown to be expressed on many lymphoma cells. We exploited this finding to develop a gene therapy strategy for treatment of canine B cell lymphoma. Ad5 was targeted to cells expressing CD40 via CD40 ligand (CD40L) and was effective in infecting CD40-expressing control cells; however, both primary canine lymphoma cells and cell lines demonstrated limited evidence of transduction. Following receptor binding, adenovirus entry into cells may require interaction with α(v)β(3/5) integrins; we demonstrate that canine lymphoma cells are deficient in these integrins. Reduced α(v)β(3) integrin expression may render these cells incapable of internalizing Ad vectors. Thus, any viral targeting approaches for treatment of canine lymphoma must also take into account the potential lack of internalization signals.

p67/MetAP2 suppresses K-RasV12-mediated transformation of NIH3T3 mouse fibroblasts in culture and in athymic mice

In many tumor cells, the activation and activity of extracellular signal-regulated kinases (ERK1/2) are very high because of the constitutive activation of the Ras-mediated signaling pathway. Here, we ectopically expressed the human homologue of rat eukaryotic initiation factor 2-associated glycoprotein, p67/MetAP2, in EGF-treated mouse embryonic NIH3T3 fibroblasts and C2C12 myoblasts and NIH3T3 cell lines expressing the constitutively active form of MAP kinase kinase (MEK) to inhibit the activation and activity of ERK1/2 MAP kinases. In addition, we also ectopically expressed rat p67/MetAP2 in oncogenic Ras-induced transformed NIH3T3 fibroblasts and inhibited their transformed phenotype both in culture and in athymic nude mice possibly by inhibiting angiogenesis. This inhibition of ERK1/2 MAP kinases is due to the direct binding with rat p67/MetAP2, and this leads to the inhibition of activity of ERK1/2 MAP kinases both in vitro and in vivo. Furthermore, expression of p67/MetAP2 siRNA in both NIH3T3 fibroblasts and C2C12 myoblasts causes activation and activity of ERK1/2 MAP kinases. Our results thus suggest that ectopic expression of rat p67/MetAP2 in transformed cells can inhibit the tumorigenic phenotype by inhibiting the activation and activity of ERK1/2 MAP kinases and, thus, that p67/MetAP2 has tumor suppression activity.

Therapeutic vaccination in chronic hepatitis B: preclinical studies in the woodchuck

Recommended treatment of chronic hepatitis B with interferon-α and/or nucleos(t)ide analogues does not lead to a satisfactory result. Induction of HBV-specific T cells by therapeutic vaccination or immunotherapies may be an innovative strategy to overcome virus persistence. Vaccination with commercially available HBV vaccines in patients did not result in effective control of HBV infection, suggesting that new formulations of therapeutic vaccines are needed. The woodchuck (Marmota monax) is a useful preclinical model for developing the new therapeutic approaches in chronic hepadnaviral infections. Several innovative approaches combining antiviral treatments with nucleos(t)ide analogues, DNA vaccines, and protein vaccines were tested in the woodchuck model. In this paper we summarize the available data concerning therapeutic immunization and gene therapy using recombinant viral vectors approaches in woodchucks, which show encouraging results. In addition, we present potential innovations in immunomodulatory strategies to be evaluated in this animal model.

Anticancer effect of cation lipofectin-mediated CD/5-FC suicide gene system on liver, biliary duct and pancreas carcinoma cells in vitro

AIM: To investigate the anticancer effect of the CD/5-FC suicide gene system on carcinoma cells of liver (Bel7402), bililary duct (QBC) and pancreas (Bxpc3), and to explore the possible anticancer mechanism.

METHODS: The growth curve and multiplication time of Bel-7402 QBC and Bxpc-3 were monitored by MTT; the transfection efficiency of the three kinds of carcinoma cells were detected by FACS after instant transfection. The anticancer efficiency of cation lipofectin-mediated CD/5-FC suicide gene system were monitored by MTT in vitro. Then, we analyzed the relation among multiplication time, transfection efficiency and anticancer effect; the apoptosis of CD/5-FC on the three cell lines were analyzed by FAM, and the apoptosis cells were stained by Hochest33342.

RESULTS: The multiplication time of Bel-7402, QBC and Bxpc-3 was 34.48, 64.94 and 26.29 h respectively, and difference between QBC and BEL-7402, BXPC-3 was significant (P < 0.05); the transfection efficiency of the three cell line were 26.99%, 2.25% and 30.36%, and the difference between QBC, and BEL-7402 and BXPC-3 was significant (P < 0.05); the anticancer efficiency was 83.24%, 16.97% and 92.32%, respectively. The apoptosis rates of the three kinds of carcinoma cells induced by CD/5-FC suicide gene system were 27.8%, 5.49% and 36.5%, respectively.

CONCLUSION: Carcinoma cells with shorter growth cycle and less multiplication time have higher instant transfection efficiency, and are more responsive to CD/5-FC suicide gene therapy. This suicide gene therapy may be a promising method for later malignant tumor in clinic.

Suppression of gastric cancer growth by baculovirus vector-mediated transfer of normal epithelial cell specific-1 gene

AIM: To study the inhibitory effect of baculovirus-mediated normal epithelial cell specific-1 (NES1) gene therapy on gastric cancer (GC) in vitro and in vivo.

METHODS: We first constructed recombinant baculovirus vectors and then transfected them into gastric cancer cells (SGC-7901). Efficiency of the baculovirus for gene transfer into SGC-7901 cells and cell growth curves were detected by fluorescence microscopy, Western blot and 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in vitro, respectively. The therapeutic effect of this gene therapy on GC was confirmed in xenografted nude mice. Tumor growth was determined by tumor volume, and expression of NES1 in tumor was analyzed by immunohistochemistry.

RESULTS: Baculovirus vectors were successfully transfected into SGC-7901 cells. SGC-7901 cells transfected with the NES1 gene inhibited cell growth. In the Bac-NES1 treated group, tumor growth was significantly reduced with a high level of NES1 expression

CONCLUSION: Baculovirus-mediated NES1 gene can be used in gene therapy for GC.

Clinical role of 18F-fluorodeoxyglucose positron emission tomography/computed tomography in post-operative follow up of gastric cancer: Initial results

AIM: To evaluate the clinical role of ¹⁸F-fluorodeo-xyglucose positron emission and computed tomography (¹⁸F-FDG PET/CT) in detection of gastric cancer recurrence after initial surgical resection.

METHODS: In the period from January 2007 to May 2008, 23 patients who had previous surgical resection of histopathologically diagnosed gastric cancer underwent a total of 25 ¹⁸F-FDG PET/CT scans as follow-up visits in our center. The standard of reference for tumor recurrence consisted of histopathologic confirmation or clinical follow-up information for at least 5 mo after PET/CT examinations.

RESULTS: PET/CT was positive in 14 patients (61%) and negative in 9 (39%). When correlated with final diagnosis, which was confirmed by histopathologic evidence of tumor recurrence in 8 of the 23 patients (35%) and by clinical follow-up in 15 (65%), PET/CT was true positive in 12 patients, false positive in 2, true negative in 8 and false negative in 2. Overall, the accuracy of PET/CT was 82.6%, the negative predictive value (NPV) was 77.7%, and the positive predictive value (PPV) was 85.7%. The 2 false positive PET/CT findings were actually chronic inflammatory tissue lesions. For the two patients with false negative PET/CT, the final diagnosis was recurrence of mucinous adenocarcinoma in the anastomosis in one patient and abdominal wall metastasis in the other. Importantly, PET/CT revealed true-positive findings in 11 (47.8%) patients who had negative or no definite findings by CT. PET/CT revealed extra-abdominal metastases in 7 patients and additional esophageal carcinoma in one patient. Clinical treatment decisions were changed in 7 (30.4%) patients after introducing PET/CT into their conventional post-operative follow-up program.

CONCLUSION: Whole body ¹⁸F-FDG PET/CT was highly effective in discriminating true recurrence in post-operative patients with gastric cancer and had important impacts on clinical decisions in a considerable portion of patients.