Evaluation of recurrent gastric malignancy with [F-18]-FDG positron emission tomography

Diagnostic performance of F-18 FDG PET or PET/CT for detection of recurrent gastric cancer: a systematic review and meta-analysis

BACKGROUND

This systematic review and meta-analysis investigated the diagnostic performance of F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) or PET/computed tomography (PET/CT) for the detection of disease recurrence after curative resection of gastric cancer.

METHODS

The PubMed and Embase databases, from the earliest available date of indexing through November 30, 2019, were searched for studies evaluating the diagnostic performance of F-18 FDG PET or PET/CT to detect recurrent disease after gastric cancer surgery.

RESULTS

Across 17 studies (1,732 patients), the pooled sensitivity for F-18 FDG PET or PET/CT was 0.82 (95% confidence interval [CI], 0.74-0.88) with heterogeneity of I2=76.5 (p<0.001), and the specificity was 0.86 (95% CI, 0.78-0.91) with heterogeneity of I2=94.2 (p<0.001). Likelihood ratio (LR) tests gave an overall positive LR of 6.0 (95% CI, 3.6-9.7) and negative LR of 0.2 (95% CI, 0.14-0.31). The pooled diagnostic odds ratio was 29 (95% CI, 13-63). The summary receiver operating characteristic curve indicates that the area under the curve was 0.91 (95% CI, 0.88-0.93).

CONCLUSION

The current meta-analysis showed good sensitivity and specificity of F-18 FDG PET or PET/CT for detecting recurrent disease after curative resection of gastric cancer despite heterogeneity in ethnicity, recurrence rate, histology, and interpretation method.

Accuracy of 18F-FDG PET/CT and CECT for primary staging and diagnosis of recurrent gastric cancer: A meta-analysis

Contrast-enhanced computed tomography (CECT) is commonly used for staging and diagnosing recurrent gastric cancer. Recently, 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET)/CT gained popularity as a diagnostic tool owing to advantages including dual functional and anatomical imaging, which may facilitate early diagnosis. The diagnostic performance of 18F-FDG PET/CT and CECT has been assessed in several studies but with variable results. Therefore, the present meta-analysis aimed to evaluate the accuracy of 18F-FDG PET/CT and CECT for primary TNM staging and the diagnosis of recurrent gastric cancers. A systematic search of the PubMed Central, Medline, Scopus, Cochrane and Embase databases from inception until January 2020 was performed. The Quality Assessment of Diagnostic Accuracy Study-2 tool was used to determine the quality of the selected studies. Pooled estimates of sensitivity and specificity were calculated. A total of 58 studies comprising 9,997 patients were included. Most studies had a low risk of bias. The sensitivity and specificity for nodal staging of gastric cancer were 49% (95% CI, 37-61%) and 92% (95% CI, 86-96%) for 18F-FDG PET/CT, respectively, and 67% (95% CI, 57-76%) and 86% (95% CI, 81-89%) for CECT, respectively. For metastasis staging, the sensitivity and specificity were 56% (95% CI, 40-71%) and 97% (95% CI, 87-99%) for 18F-FDG PET/CT, respectively, and 59% (95% CI, 41-75%) and 96% (95% CI, 83-99%) for CECT, respectively. For diagnosing cancer recurrence, the pooled sensitivity and specificity were 81% (95% CI, 72-88%) and 83% (95% CI, 74-89%) for 18F-FDG PET/CT, respectively, and 59% (95% CI, 41-75%) and 96% (95% CI, 83-99%) for CECT, respectively. Both 18F-FDG PET/CT and CECT were deemed highly useful for diagnosing recurrent gastric cancer due to their high sensitivities and specificities. However, these techniques cannot be used to exclude or confirm the presence of lymph node metastases or recurrent gastric cancer tumors, but can be used for the confirmation of distal metastasis.

18F-fluorodeoxyglucose positron emission tomography-computed tomography scan after gastric endoscopy in those who present with non-specific symptoms, is it necessary or not?

Background and Aims:

Retrospectively analyze the sensitivity of ¹⁸F-fluorodeoxyglucose positron emission tomography-computed tomography (¹⁸F-FDG PET-CT) in the diagnosis of gastric malignancy compared with gastric endoscopy in persons with nonspecific symptoms and evaluate the necessity of ¹⁸F-FDG PET-CT scan before surgery.

Materials and Methods:

A total of 53 patients with gastric malignancy proven by surgery and pathology were enrolled in the study. All the patients underwent gastric endoscopy and PET-CT scan before surgery. And the PET-CT images were interpreted by the observers who were blinded to the results of the gastric endoscopy. The sensitivity of gastric endoscopy, ¹⁸F-FDG PET-CT, and serum tumor markers in the diagnosis of gastric malignancy were calculated ultimately.

Results:

Of 53 gastric malignancy patients, five cases were proven to be false-negative detected by gastric endoscopy, and the sensitivity of which was 90.57%. The sensitivity of PET scan alone was 86.79%, which was observed no significant difference to that of gastric endoscopy diagnosis, P = 0.54. While all of the patients had been detected positive on PET-CT images, the sensitivity of which was significantly higher than that of the gastric endoscopy diagnosis or that of the serum tumor markers, P < 0.001. And the FDG uptake was positively correlated with the depth of the cancer invasion into the gastric wall (P < 0.0001) and the degree of lymph nodes infiltration (P = 0.02). It also various from different differentiation degree significantly, P = 0.04.

Conclusions:

¹⁸F-fluorodeoxyglucose PET-CT could detect gastric carcinoma in persons with nonspecific symptoms which showed negative in gastric endoscopy. And it is necessary to be aware of the possibility of gastric malignancy when the result of PET-CT scan is positive.

Gastric Cancer with Radiographically Occult Metastatic Disease: Biology, Challenges, and Diagnostic Approaches

Gastric adenocarcinoma is an aggressive cancer that demonstrates heterogeneous biology depending on patient ethnicity, tumor location, tumor type, and genetic profile. It remains the third leading cause of cancer deaths worldwide and was estimated to result in 782,000 deaths in 2018. Challenges exist in accurately assessing the disease burden, as available radiological staging often underestimates metastatic disease. This diagnostic handicap, along with the poor understanding of the heterogeneous biology of gastric cancer, has hindered the development of effective therapeutic solutions and thus halted improvement in patient outcomes over the last few decades. The management of occult peritoneal disease is complicated, as most patients are understaged by standard imaging studies and therefore thought to have local diseases. In this article, we systematically review recent literature on the limitations that are associated with standard radiographic staging, discuss recent molecular biology advances to better identify and diagnose occult peritoneal disease, and propose possible management strategies to approach this complicated clinical problem.

Gastric Cancer: Recent Molecular Classification Advances, Racial Disparity, and Management Implications

Gastric adenocarcinoma remains an aggressive and poorly understood malignancy with a heterogeneous presentation and tumor biology. The current histologic and anatomic classification has been ineffective in guiding therapy, with only marginal improvement in outcome over time. Furthermore, the variation in presentation and disease among racial and ethnic groups amplifies the complexity of this cancer. An understanding of the clinical and molecular variability is important for effective treatment. Recent advances in molecular biology have better defined gastric cancer subtypes. We systematically review recent literature on the molecular classification of gastric adenocarcinoma and the associated management implications, with an emphasis on Hispanic and Native American populations.

Solitary metastasis to a superior mediastinal lymph node after distal gastrectomy for gastric cancer: a case report

Background

Mediastinal lymph node metastases occasionally occur in patients of advanced gastric cancer of the cardia with esophageal invasion, but they rarely occur in patients with gastric cancer of other sites. This report describes a case of a solitary metastasis to t a superior mediastinal lymph node after distal gastrectomy for gastric cancer of the antrum.

Case presentation

A 70-year-old man underwent curative distal gastrectomy for advanced gastric cancer of the antrum (pT2pN2M0, stage IIB). Postoperatively, he underwent adjuvant chemotherapy with S-1 (100 mg/day). Although the serum levels of his tumor markers increased after surgery, computed tomography scans did not detect evidence of early recurrence in the superior mediastinum. However, a ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) scan showed accumulation of fluorodeoxyglucose in the upper mediastinum with no evidence of recurrence elsewhere. Therefore, a solitary superior mediastinal lymph node was suspected to have a metastatic lesion derived from the gastric cancer. The patient underwent tumor resection right mini-thoracotomy two years and three months following gastrectomy. A pathological examination demonstrated moderately differentiated adenocarcinoma, confirming that it was a metastatic adenocarcinoma from the gastric cancer. The patient developed recurrences in the superior mediastinum and several right costa six months following the second surgery. He was treated with chemotherapy, but he died 18 months after the second operation.

Conclusion

We present a rare case of a solitary metastasis to a superior mediastinal lymph node after distal gastrectomy for gastric cancer. An FDG-PET scan is useful for the diagnosis of mediastinal lymph node metastasis in gastric cancer. Metastasis to the superior mediastinal lymph nodes from gastric cancer in sites other than the cardia suggests systemic expansion of gastric cancer, and therefore, even a solitary metastasis may be related to a poor prognosis.

Prognostic significance of interim 18 F-fluorodeoxyglucose positron emission tomography-computed tomography volumetric parameters in metastatic or recurrent gastric cancer

AIM

To evaluate the prognostic role of interim analysis of 18F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET/CT) volumetric parameters in patients with recurrent or metastatic advanced gastric cancer (AGC) treated with fluoropyrimidine-based palliative chemotherapy.

METHODS

Forty-four patients who underwent baseline and interim PET/CT scanning during palliative chemotherapy were analyzed retrospectively. Initial and change of metabolic parameters (MP) - metabolic tumor volume (MTV), tumor lesion glycolysis (TLG) and maximum and mean standardized uptake values (SUV) were measured with PET/CT. Metabolic change was measured by ∆MP (%)  =  (MP_interim  - MP_initial )/MP _initial   ×  100. Independent t-test was employed to compare values of initial, interim and change of metabolic parameters between each response group. Log-rank test was employed for univariate analysis, and multivariate analysis was performed using the Cox proportional hazards regression model to determine independently significant prognostic factors.

RESULTS

Reduced percentage values of maximum and mean SUV on interim PET/CT and initial values of volumetric parameters (MTV and TLG) were significant predicting factors to response to fluoropyrimidine-based palliative chemotherapy. The decreased percentage values of metabolic parameters as well as maximum and mean SUV with receiver operating characteristic (ROC) curve determined cut-off points were significant prognostic factors for overall survival and progression-free survival in univariate and multivariate analyses.

CONCLUSION

Measurement of metabolic decrease of volumetric parameters by interim PET/CT analysis is useful to determine the prognosis of patients with recurrent or metastatic AGC.

Evaluation of recurrence in gastric carcinoma: Comparison of contrast-enhanced computed tomography and positron emission tomography/computed tomography

AIM

To compare the value of contrast-enhanced abdominal computed tomography (CT) and fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for detecting gastric carcinoma recurrence.

METHODS

We retrospectively examined data from 2475 patients who underwent both contrast-enhanced abdominal CT and FDG PET/CT for the surveillance of gastric carcinoma curative resection. Patients had an interval of less than 1 mo between their CT and PET/CT scans. Sixty patients who had recurrence were enrolled. Among 1896 patients who did not have recurrence, 60 were selected by simple random sampling. All CT and PET/CT images were reviewed retrospectively by two reviewers blinded to all clinical and pathologic information except curative resection due to gastric carcinoma.

RESULTS

The pathological stage of the recurrence group was statistically significantly higher than that of the control group (P < 0.001). In the 60 patients who had recurrence, there were 79 recurrent lesions. Forty-four patients had only one location of recurrence, 13 patients had two locations, and 3 patients had three. In the detection of patient-based overall recurrence, no statistically significant differences existed between the two modalities (P = 0.096). However, for peritoneal carcinomatosis, CT had a statistically significantly higher sensitivity compared to PET/CT (96% vs 50%, P = 0.001). Adenocarcinoma was the most common type of gastric carcinoma. On the pathology-based analysis, CT also had a statistically significantly higher sensitivity compared to PET/CT (98% vs 80%, P = 0.035).

CONCLUSION

Contrast-enhanced CT was superior to PET/CT in the detection of peritoneal carcinomatosis and pathologic type of adenocarcinoma.

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.

The Role of 18F-FDG PET/CT in the Evaluation of Gastric Cancer Recurrence

Objective: F-18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) has been widely used for staging, re-staging and for monitoring therapy-induced changes and response to therapy in patients with various types of cancer, but its utilization for gastric cancer has been limited. This study aimed to assess the diagnostic performance of 18F-FDG PET/CT for detecting recurrence in gastric cancer patients with radiologic or clinical suspicion of recurrence and its clinical impact on making decision.

Methods: We performed a retrospective review of 130 consecutive patients who underwent PET/CT scans for post-treatment surveillance of gastric cancer between January 2008 and March 2012. The mean time between the initial diagnosis of gastric cancer and PET/CT studies was 44 weeks with a median of 18 weeks. The number and site of positive FDG uptake were analyzed and correlated with the final diagnosis by calculating the diagnostic values. We evaluated the diagnostic accuracy of PET/CT for detecting the recurrence in terms of whether or not histology had been SRC/musinous adenocarcinoma. The changes in the clinical management of patients were also evaluated according to the results of PET/CT.

Results: Of all 130 patients, 91 patients were confirmed to have true recurrence. The sensitivity, specificity, positive predictive value, negative predictive value and the accuracy of PET/CT for diagnosing true recurrence on a per-person basis were 91.2%, 61.5%, 84.6%, 75.0% and 82.3% respectively. Final diagnoses were confirmed histopathologically in 59 (45.4%) of 130 patients and by clinical and radiological follow-up in the remaining 71 (54.6%) patients. In the subgroup with SRC/mucinous adenocarcinoma differentiation of the primary tumor, there was no statistically significant difference in terms of diagnostic accuracy of PET/CT on a per-person basis. In addition, PET/CT results changed the patients’ management in 20 (15%) cases.

Conclusions: 18F-FDG PET/CT can provide useful information in discriminating true recurrence in patients with suspected gastric cancer recurrence and may have significant impact on clinical decisions/patient management in a considerable percentage of patients.

Role of fluorine 18 fluorodeoxyglucose positron emission tomography/computed tomography in gastrointestinal cancers

Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) has become a routine imaging modality for many malignancies and its use is currently increasing. In the present review article, we will summarize the evidence for FDG-PET/CT use in digestive cancers (excluding neuroendocrine tumours), and review the existing recommendations. While PET/CT is nowadays considered to be an important tool in the initial workup of oesophageal and anal cancers, new data are emerging regarding its use in assessing therapeutic efficacy, radiotherapy treatment planning, and detection of recurrence in case of isolated tumour marker elevation. Moreover, PET/CT may help decision making by detecting distant metastatic sites especially in potentially resectable metastatic colorectal cancer and, to a lesser extent, in localized gastric and pancreatic cancers. Finally, incidental focal colonic FDG uptakes require exploration by colonoscopy, as they are often associated with premalignant or malignant lesions.

[Synopsis on clinical practice guideline of gastric cancer in Korea: an evidence-based approach]

Although, gastric cancer is quite common in Korea, the treatment outcome is relatively favorable compared to that of Western countries. However, there is no Korean multidisciplinary guideline for gastric cancer and thus, a guideline adequate for domestic circumstances is required. Experts from related societies developed 22 recommendation statements for the diagnosis (n=9) and treatment (n=13) based on relevant key questions. Evidence levels based on systematic review of literatures were classified as five levels from A to E, and recommendation grades were classified as either strong or weak. The topics of this guideline cover diagnostic modalities (endoscopy, endoscopic ultrasound, radiologic diagnosis), treatment modalities (surgery, therapeutic endoscopy, chemotherapy, radiotherapy) and pathologic evaluation. External review of the guideline was conducted at the finalization phase.

[18F]Fluorodeoxyglucose PET/Computed Tomography in Gastrointestinal Malignancies

This article discusses the current state-of-the-art application of 2-deoxy-2-[(18)F]fluoro-d-glucose (FDG)-PET and FDG-PET/computed tomography (CT) in the management of patients with gastrointestinal malignancies. Gastrointestinal malignancies include many different cell types, several common malignancies of which may be imaged by FDG-PET/CT. This review focuses on gastric carcinoma, pancreatic carcinoma, hepatocellular carcinoma, cholangiocarcinoma, colorectal carcinoma, and stroma cell tumors. The role of FDG-PET/CT in staging these malignancies is discussed, in addition to (re)staging, detection of recurrent disease, patient selection/prognostication, and response assessment, using the currently available literature.

Clinical practice guidelines for gastric cancer in Korea: an evidence-based approach

Although gastric cancer is quite common in Korea, the treatment outcome is relatively favorable compared to those in western countries. However, there are currently no Korean multidisciplinary guidelines for gastric cancer. Experts from related societies developed guidelines de novo to meet Korean circumstances and requirements, including 23 recommendation statements for diagnosis (n=9) and treatment (n=14) based on relevant key questions. The quality of the evidence was rated according to the GRADE evidence evaluation framework: the evidence levels were based on a systematic review of the literature, and the recommendation grades were classified as either strong or weak. The applicability of the guidelines was considered to meet patients' view and preferences in the context of Korea. The topics of the guidelines cover diagnostic modalities (endoscopy, endoscopic ultrasound, and radiologic diagnosis), treatment modalities (surgery, therapeutic endoscopy, chemotherapy, and radiotherapy), and pathologic evaluation. An external review of the guidelines was conducted during the finalization phase.

Imaging of Gastric Cancer Metabolism Using 18 F-FDG PET/CT

Aerobic glycolysis has been the most important hypothesis in cancer metabolism. It seems to be related to increased bioenergetic and biosynthetic needs in rapidly proliferating cancer cells. To this end, F-18 fluorodeoxyglucose (FDG), a glucose analog, became widely popular for the detection of malignancies combined with positron emission tomography/computed tomography (PET/CT). Although the potential roles of FDG PET/CT in primary tumor detection are not fully established, it seems to have a limited sensitivity in detecting early gastric cancer and mainly signet ring or non-solid types of advanced gastric cancer. In evaluating lymph node metastases, the location of lymph nodes and the degree of FDG uptake in primary tumors appear to be important factors affecting the diagnostic accuracy of PET/CT. In spite of the limited sensitivity, the high specificity of PET/CT for lymph node metastases may play an important role in changing the extent of lymphadenectomy or reducing futile laparotomies. For peritoneal metastases, PET/CT seems to have a poorer sensitivity but a better specificity than CT. The roles of PET/CT in the evaluation of other distant metastases are yet to be known. Studies including primary tumors with low FDG uptake or peritoneal recurrence seem suffer from poorer diagnostic performance for the detection of recurrent gastric cancer. There are only a few reports using FDG PET/CT to predict response to neoadjuvant or adjuvant chemotherapy. A complete metabolic response seems to be predictive of more favorable prognosis.

Follow-up after gastrectomy for cancer: an appraisal of the Italian research group for gastric cancer

BACKGROUND

The Italian Research Group for Gastric Cancer supports the practice of follow-up after radical surgery for gastric cancer.

METHODS

This multicenter, retrospective study (1998-2009) included patients with T1-4N0-3M0 gastric cancer who had undergone D2 gastrectomy and lymphadenectomy, with at least 15 lymph nodes examined, and who had developed recurrent disease. Timing and site of recurrence were correlated to the actual scheduled follow-up timing and modalities.

RESULTS

From eight centers, 814 patients with recurrent cancer and over 1,754 (46.4 %) patients undergoing gastrectomy were investigated (median follow-up 31 months). The most frequent sites of recurrence were local/regional lymph nodes (35.4 %), liver (24.3 %), peritoneum (30.3 %), lung (10.4 %) and intraluminal (7.5 %). Ninety-four percent of the recurrences were diagnosed within 2 years and 98 % within 3 years. Thoracoabdominal computed tomography (CT) scan and (18)F-fluoro-2-deoxy-D-glucose positron emission tomography (18-FDG-PET) detected more than 90 % of recurrences, abdominal ultrasound detected 70 % and tumor markers detected 40 %, while <10 % were identified by physical examination, chest X-ray, and upper gastrointestinal endoscopy. Twenty-six percent of patients with recurrence were treated, but only 3.2 % were treated with potentially radical intent.

CONCLUSION

Oncological follow-up after radical surgery for gastric cancer should be focused in the first 3 years, and based mainly on thoracoabdominal CT scan and 18-FDG-PET.

Follow-up: the evidence

There is currently no consensus on the best strategy for the follow-up of patients who have undergone surgical treatment with curative intent for gastric cancer. The wide variation in recommendations for surveillance among international experts and hospital schedules clearly reflects a lack of an established body of evidence on this subject. Consequently, most of the international guidelines aimed at early detection of disease recurrence gloss over details concerning the mode, duration, and intensity of surveillance since they cannot be based on an acceptable grade of recommendation. Very few report anything other than the detection of recurrences or death as the primary endpoints, and, given the poor survival of patients with recurrent gastric cancer, the prognostic effect of early detection seems doubtful. In recent years, an increasing focus on evidence-based medicine, which has coincided with a growing concern about costs and efficiency in medicine, has caused a reevaluation of most surveillance practices. In this paper, we review and discuss the current body of evidence and follow-up practices after curative resection of gastric cancer.

18F-FDG PET-CT for detecting recurrent gastric adenocarcinoma: results from a Non-Oriental Asian population

OBJECTIVE

To evaluate the utility of fluorine-18 fluorodeoxyglucose (18F-FDG) PET-CT in the diagnosis of recurrent gastric adenocarcinoma in a Non-Oriental Asian population.

METHODS

In this retrospective analysis, data from 72 Non-Oriental Asian patients, who underwent 93 18F-FDG PET-CT studies, were evaluated. All patients had histopathologically proven gastric adenocarcinoma, for which they had undergone primary treatment. PET-CT was performed for suspected recurrence or for post-therapy surveillance. PET-CT findings were analysed on a per-patient and per-region basis (local/lymph node/liver/lung/bone/others). A combination of clinical follow-up (minimum 6 months; range: 6-36 months), imaging follow-up and/or histopathology (when available) was taken as the reference standard. Sensitivity, specificity and predictive values were calculated for PET-CT on both a per-study and per-lesion basis.

RESULTS

The mean patient age was 52.8 ± 11.8 years (male/female: 52/20). Out of 93 PET-CT studies, 56 (60.2%) were positive and 37 (39.8%) were negative for recurrent disease. On per-study-based analysis, 18F-FDG PET-CT has a sensitivity, specificity and accuracy of 95.9, 79.5 and 88.1%, respectively. The accuracy of 18F-FDG PET-CT was 89.2% for local recurrence, 94.6% for lymph nodes, 96.7% for liver, 96.7% for lung, 98.9% for bone and 98.9% for other sites. The accuracy of 18F-FDG PET-CT was lower for local recurrence as compared with that for liver (P=0.012) and bone (P=0.012). No significant difference was found in the diagnostic accuracies for other regions.

CONCLUSION

18F-FDG PET-CT is highly sensitive and specific for detecting recurrence in patients with gastric adenocarcinoma. It shows high accuracy both on a per-patient and per-lesion basis.

SUVmax/THKmax as a biomarker for distinguishing advanced gastric carcinoma from primary gastric lymphoma

Background

Gastric carcinoma and primary gastric lymphoma (PGL) are the two most common malignancies in stomach. The purpose of this study was to screen and validate a biomarker of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) for distinguishing advanced gastric carcinoma (AGC) from PGL for clinical applications.

Methodology/Principal Findings

We reviewed PET/CT scans collected from January 2008 to April 2012 of 69 AGC and 38 PGL (14 low-grade mucosa-associated lymphoid tissue [MALT], 24 non-MALT aggressive non-Hodgkin lymphoma [ANHL]) with a focus on FDG intensity (maximum standardized uptake value [SUVmax]) of primary lesions and its CT-detected abnormalities, including maximal gastrointestinal wall thickness (THKmax) and mucosal ulcerations. Gastric FDG uptake was found in 69 (100%) patients with AGC and 36 (95%, 12 MALT vs. 24 ANHL)with PGL. The presence of CT-detected abnormalities of AGC and PGL were 97% (67/69) and 89% (12 MALT vs. 22 ANHL), respectively. After controlling for THKmax, SUVmax was higher with ANHL than AGC (17.10±8.08 vs. 9.65±5.24, p<0.05) and MALT (6.20±3.60, p<0.05). THKmax did not differ among MALT, ANHL and AGC. Mucosal ulceration was more common with AGC (n = 9) than PGL (n = 2),but the difference was not statistically significant (p>0.05). Cross-validation analysis showed that for distinguishing ANHL from AGC, the classifier with SUVmax as a feature achieved a correct classification rate of 81% with thresholds 13.40±1.12 and the classifier with SUVmax/THKmax as a feature achieved a correct classification rate of 83% with thresholds 7.51±0.63.

Conclusions/Significance

SUVmax/THKmax may be as a promising biomarker of FDG-PET/CT for distinguishing ANHL from AGC. Structural CT abnormalities alone may not be reliable but can help with PET assessment of gastric malignancies. ¹⁸F-FDG PET/CT have potential for distinguishing AGC from PGL at the individual level.

18 F-fluorodeoxyglucose positron emission tomography to evaluate recurrent gastric cancer: a systematic review and meta-analysis

BACKGROUND AND AIM

We aimed to explore the role of the diagnostic accuracy of (18) F-fluorodeoxyglucose positron emission tomography ((18) F-FDG PET) in detecting recurrent gastric cancer through a systematic review and meta-analysis.

METHODS

The MEDLINE, EMBASE, Cancerlit, and Cochrane Library database, from January 2001 to July 2011, were searched for studies evaluating the diagnostic performance of (18) F-FDG PET in detecting recurrent gastric cancer. We determined the sensitivities and specificities across studies, calculated positive and negative likelihood ratios (LR+ and LR-), and constructed summary receiver operating characteristic curves. We also compared the performance of (18) F-FDG PET with computed tomography (CT) by analyzing studies that had also used these diagnostic methods on the same patients.

RESULTS

Across nine studies (526 patients), the overall sensitivity of (18) F-FDG PET was 0.78 (95% confidence interval [CI]: 0.68-0.86), and the overall specificity was 0.82 (95% CI: 0.76-0.87). Overall, LR+ was 3.52 (95% CI: 2.68-4.63) and LR- was 0.32 (95% CI: 0.22-0.46). In studies in which both (18) F-FDG PET and other diagnostic tests were performed, the sensitivity and specificity of (18) F-FDG PET were 0.72 (95% CI: 0.62-0.80) and 0.84 (95% CI: 0.77-0.90), respectively; of contrast CT, they were 0.74 (95% CI: 0.64-0.83) and 0.85 (95% CI: 0.78-0.90), respectively; and of combined PET and CT, they were 0.75 (95% CI: 0.67-0.82) and 0.85 (95% CI 0.79-0.90), respectively. Study sensitivity was not correlated with the prevalence of recurrent gastric cancer.

CONCLUSION

(18) F-FDG PET has good diagnostic performance in the overall evaluation of recurrent gastric cancer, but still has some limited performance compared with contrast CT. (18) F-FDG PET combined with CT might improve the diagnostic performance in detecting recurrent gastric 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.

Significance of SUV on Follow-up F-18 FDG PET at the Anastomotic Site of Gastroduodenostomy after Distal Subtotal Gastrectomy in Patients with Gastric Cancer

PURPOSE

The aim of this study was to characterize the patterns of fluorodeoxyglucose (FDG) uptake on F-18 FDG positron emission tomography/computed tomography (FDG PET/CT) at the anastomotic site of gastroduodenostomy after distal subtotal gastrectomy in patients with gastric cancer.

METHODS

From May 2007 to May 2010, two or more follow-up measurements using FDG PET/CT scans were done for 19 patients (11 men, 8 women; mean age, 62.0 ± 10.3 years) who underwent distal subtotal gastrectomy with gastroduodenostomy between February 2006 and March 2008 for detecting gastric cancer recurrence at our medical center. The FDG PET/CT images were retrospectively reviewed. Patients with local recurrence, regional nodal metastasis or distant metastasis on follow-up studies were excluded. CT and endoscopy were done within 1 month before or after the FDG PET/CT scan. Eight patients had two follow-ups of FDG PET/CT, and 11 patients had three follow-ups. The mean interval between surgery and the first follow-up FDG PET/CT was 12.9 ± 0.8 months (n = 19); between the first and second it was 12.3 ± 1.0 months (n = 19); between the second and third it was 11.6 ± 0.7 months (n = 11). The F-18 FDG uptakes at the anastomotic site and fundus in the remnant stomach were measured by maximum standardized uptake value (SUVmax) using a region of interest technique.

RESULTS

The SUVmax at the anastomotic site was significantly higher than that of the fundus on all series of first, second and third follow-up studies (3.3 ± 1.1 vs. 2.1 ± 0.7, p < 0.001: 3.1 ± 0.9 vs. 2.2 ± 0.7, p = 0.001: 3.0 ± 0.6 vs. 2.1 ± 0.7, p = 0.006, respectively). The SUVmax for the anastomotic site and fundus, and SUVmax ratio for the anastomotic site over the fundus were not significantly different throughout the series.

CONCLUSION

The SUVmax at the anastomotic site is significantly higher than that of the fundus and does not decrease significantly over time. Therefore, the local recurrence of gastric cancer after surgery could not be definitely differentiated from physiologic uptake or postoperative inflammatory change.

Detecting the recurrence of gastric cancer after curative resection: comparison of FDG PET/CT and contrast-enhanced abdominal CT

The purpose of this study was to evaluate the value of fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) for detecting the recurrence of gastric cancer. We performed a retrospective review of 139 consecutive patients who underwent PET/CT and contrast-enhanced abdominal CT (CECT) for surveillance of gastric cancer after curative resection. Recurrence of gastric cancer was validated by histopathologic examination for local recurrence or serial imaging study follow-up with at least 1 yr interval for recurrence of distant metastasis form. Twenty-eight patients (20.1%) were confirmed as recurrence. On the patient based analysis, there was no statistically significant difference in the sensitivity, specificity and accuracy of PET/CT (53.6%, 84.7%, and 78.4%, respectively) and those of CECT (64.3%, 86.5%, and 82.0%, respectively) for detecting tumor recurrence except in detection of peritoneal carcinomatosis. Among 36 recurrent lesions, 8 lesions (22.2%) were detected only on PET/CT, and 10 lesions (27.8%) only on CECT. PET/CT had detected secondary malignancy in 8 patients. PET/CT is as accurate as CECT in detection of gastric cancer recurrence after curative resection, excepting detection of peritoneal carcinomatosis. Moreover, additional PET/CT on CECT could improve detection rate of tumor recurrence and provide other critical information such as unexpected secondary malignancy.

Use of laparoscopy as an alternative to computed tomography (CT) and positron emission tomography (PET) scans for the detection of recurrence in patients with gastric cancer: a pilot study

BACKGROUND

This study aimed to evaluate laparoscopy as a diagnostic method for detecting recurrence in patients with advanced gastric cancer.

METHODS

Diagnostic laparoscopy was performed for 12 patients with insufficient evidence of intraabdominal gastric cancer recurrence by computed tomography or positron emission tomography. By comparing laparoscopic observations with conventional radiologic results, the diagnostic accuracy of laparoscopy was assessed.

RESULTS

In 11 (92%) of 12 cases of recurrence not diagnosed by imaging studies, laparoscopic examination confirmed the case as a recurrence. Using diagnostic laparoscopy, retroperitoneal lymph node recurrence was confirmed in two patients, peritoneal seeding nodules in five patients, and recurrent masses invading the mesocolon in two patients. Two patients had no definitive recurrence grossly but were confirmed as recurrence cases by washing cytology during the laparoscopic procedure. One patient had a duodenal stump recurrence. No patients experienced operation-related morbidity.

CONCLUSION

Laparoscopy is a safe and feasible method for detecting recurrence with acceptable accuracy. This approach provides more accurate information than conventional imaging methods.

Oncologic effectiveness of regular follow-up to detect recurrence after curative resection of gastric cancer

BACKGROUND

While clinicians routinely follow up gastric cancer patients after curative resection to detect recurrence, the effectiveness of regular follow-up has not been proven, and no consensus has been reached regarding follow-up programs.

METHODS

Of the 1,767 patients who underwent curative resection for gastric cancer from 2001 to 2004, 310 (17.5%) developed recurrence during follow-up. The oncologic effectiveness of follow-up was evaluated using recurrence detection rates during follow-up and survivals. Clinicopathologic characteristics, the detection tools used, and times lapsed between recurrence and previous examinations were also investigated.

RESULTS

Two hundred thirty-three (75.2%) of the 310 patients who developed recurrence were detected by regular follow-up (detected group). The frequencies of undifferentiated and diffuse-type recurrences were higher in patients with recurrence detected based on patient-initiated findings (undetected group) than in the detected group. Computed tomography and tumor markers were the first detection tools that yielded positive findings. Times between recurrence detection and previous examinations ranged from 2.8 to 5.3 months over the first 2 years. No difference in overall survival was found between the detected and undetected groups (log rank, P = 0.2).

CONCLUSIONS

The oncologic effectiveness of regular follow-up after curative resection for gastric cancer was found to be unsatisfactory. A large-scale randomized controlled trial is required to identify the effectiveness of regular follow-up in terms of its oncologic, functional, psychological, and economical aspects.

The role of ¹⁸F-FDG PET/CT in the assessment of suspected recurrent gastric cancer after initial surgical resection: can the results of FDG PET/CT influence patients' treatment decision making?

PURPOSE

(18)F-fluorodeoxyglucose (FDG) PET/CT has been widely used for staging, re-staging and for monitoring therapy-induced changes and response to therapy in patients with various types of cancer, but its utilization for gastric cancer has been limited. The purpose of this study was to evaluate the clinical role of FDG PET/CT in the detection of gastric cancer recurrence as compared with diagnostic CT and to assess the impact of FDG PET/CT results on patients' treatment planning.

METHODS

Thirty-four patients with suspected recurrent gastric cancer, who had previously undergone curative gastrectomy and lymph node dissection, were retrospectively analysed. The diagnostic CT and FDG PET/CT imaging were performed for all patients as clinically indicated. The results of FDG PET/CT were compared with the findings of the diagnostic CT. The changes in the clinical management of patients according to the results of FDG PET/CT were also evaluated.

RESULTS

FDG PET/CT was performed in 19 patients (55.9%) due to the suspicion of distant metastasis at diagnostic CT. The remaining 15 patients were suspected to have local recurrence at diagnostic CT (n = 4) or gastroscopy (n = 1) and due to an increase in tumour markers or clinical manifestations (n = 10). The FDG PET/CT result was positive in 23 patients (67.6%) and negative in 11 patients (32.4%). In total, 24 (70.6%) of the 34 patients had documented recurrent disease by histopathology in 7 (29.1%) and by clinical follow-up in 17 (70.9%), while 11 patients had no evidence of recurrent disease. FDG PET/CT correctly confirmed recurrent disease in 23 of the patients with recurrence and it was classified as true-positive in these patients. However, FDG PET/CT was false-negative in one patient but recurrent disease was confirmed by histopathology. The overall sensitivity, specificity, accuracy, positive and negative predictive values of FDG PET/CT were significantly superior to those of diagnostic CT (95.8 vs 62.5%, 100 vs 10%, 97 vs 47%, 100 vs 62.5% and 90.9 vs 10%, respectively, p = 0.012) in the detection of recurrent gastric cancer after initial surgery. The FDG PET/CT results changed the patients' management in 18 (52.9%) cases by leading to the use of previously unplanned treatment procedures in 9 (50%) patients and the avoidance of previously planned therapeutic procedures in 9 (50%) patients.

CONCLUSION

FDG PET/CT is a superior post-therapy surveillance modality for the diagnosis of recurrent gastric cancer compared with diagnostic CT imaging after initial surgery. In addition, integrated FDG PET/CT was specifically helpful in optimizing the treatment plan and it might play an important role in treatment stratification in the future.

Early detection of recurrence after endoscopic treatment for early gastric cancer

OBJECTIVE

Although there have been many reports regarding clinical outcomes of endoscopic treatment for early gastric cancer (EGC), little is known about detection of recurrence after endoscopic submucosal dissection (ESD). This study aims to clarify the clinical value of serological marker or imaging tools, including conventional CT and PET-CT scans, in detecting recurrent gastric cancer after ESD in Korea.

MATERIAL AND METHODS

From July 2004 to March 2008, 212 patients who had received ESD for EGC were enrolled in the study. For preoperative staging, conventional CT and PET-CT scans were performed in 141 patients, and for detection of recurrence of cancer, conventional CT, PET-CT scans and tumour marker; CEA, CA19-9, AFP were checked in 165 patients.

RESULTS

The local recurrence rate was 4.7% (10/212) during the study period. At 9 months after endoscopic treatment, 3 cases recurred. Four showed recurrence at 12 months, 2 at 18 months and 1 at 24 months. The positive rate was 7.1% (10/141) in conventional CT and 0% (0/24) in PET-CT scans for preoperative staging. Conventional CT and PET-CT scans could not detect local recurrence of cancer during the follow-up period. Tumour markers did not show any significant correlation with recurrence of cancer.

CONCLUSIONS

The study suggests that conventional CT, PET-CT scans and tumour marker have no role in the primary surveillance of early gastric cancer and/or in detecting recurrence after endoscopic treatment. For early diagnosis of recurrence after endoscopic treatment, a biopsy specimen from the endoscopic examination has to be obtained at regular intervals.

Advances in the management of gastric cancer

Gastric cancer is a common malignancy in our country and patients continue to present at an advanced stage. Following confirmation of diagnosis, CT scan, endoscopic ultrasound and laparoscopy are the essential staging modalities. Radical gastrectomy remains the initial treatment of choice. Although controversy persists about the extent of lymph node dissection, there is a general consensus in performing D2 dissection but with preservation of pancreas and spleen. Patients who have high risk of relapse are treated with postoperative chemoradiotherapy. The regimen of preoperative chemotherapy followed by gastrectomy and postoperative chemotherapy has also become important in recent years. Both these chemotherapeutic options confer survival advantage and patients need to be appraised about various treatment strategies at the very outset.

Detecting recurrence of gastric cancer: the value of FDG PET/CT

PURPOSE

In order to assess the diagnostic performance of Positron emission tomography/Computed tomography (PET/CT) for detecting recurrence in gastric cancer patients with clinical or radiologic suspicion of recurrence after surgical resection.

MATERIALS AND METHODS

Over a 4-year period, 105 post-operative patients with gastric cancer, who underwent PET/CT due to clinical or radiologic suspicion of recurrence during follow-up, were collected after confirming their PET/CT findings. The number and site of positive FDG uptake were retrospectively analyzed, and were correlated with the final diagnosis, by calculating the diagnostic values and assessing the causes of misdiagnosis.

RESULTS

Of all 105 patients, 75 patients were confirmed to have true recurrence with 108 recurrence sites. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy for diagnosing true recurrence on a per-person basis were 75%, 77%, 89%, 55%, and 75%, respectively. On a per-lesion basis, 75 (69%) of 108 true recurrences showed positive FDG uptake, while 75 (89%) of 84 positive FDG uptake was confirmed to have true recurrence.

CONCLUSION

PET/CT was relatively accurate in detecting recurrence in post-operative patients with gastric cancer. Moreover, PET/CT might be helpful in confirming the presence of recurrence particularly in patients who were highly suspicious of recurrence, because of its high positive predictability.

Duodenal stump cancer after Billroth-II distal gastrectomy for gastric cancer

Duodenal cancer is an uncommon neoplasm and it mostly arises from the periampullary area. However, metachronous or even recurrent cancer at the duodenal stump following Billroth II type distal gastrec tomy for gastric cancer is extremely rare and, to our knowledge, has not yet been reported. A 68-year-old man underwent Billroth II distal gastrectomy with D2 lymph node dissection for an advanced gastric cancer. At that time the tumor stage was T2bN3M0, with 44 of 78 retrieved lymph nodes showing metastasis. He was well without recurrence for 3 years; however, he visited our hospital because of the abrupt onset of dizziness and tarry stool. A polypoid tumor that bled easily when touched was found at the end of the afferent loop of the duodenal stump by gastrofiberscopic examination, and it was proven to be an adenocarcinoma by endoscopic biopsy. Fortunately, additional studies, including abdominal computed tomography and positron emission tomography-computed tomography, showed no other sites of recurrence. The patient underwent pancreaticoduodenectomy for local control of the recurrent tumor at the duodenal stump, and the pathologic findings, based on immunohistochemical staining, strongly suggested that the duodenal tumor was metachronous in nature rather than recurrent.

FDG-PET has no definite role in preoperative imaging in gastric cancer

BACKGROUND

Gastric cancer is fourth on the incidence list of cancers worldwide with a high disease-related mortality rate. Curation can only be achieved by a radical resection including an adequate lymphadenectomy. However, prognosis remains poor and cancer recurrence rates are high, also due to lymph node metastases. To improve outcome, (neo)adjuvant treatment strategies with chemo- and/or radiotherapy regimes are employed.

AIMS

Accurate staging of gastric cancer at primary diagnosis is essential for adequate treatment. In this non-systematic review the role 18-F-Fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) in preoperative staging is investigated. Furthermore, the results of neoadjuvant chemotherapy-induced tumour response monitoring by FDG-PET are discussed.

RESULTS AND CONCLUSION

It is concluded that currently FDG-PET has no role in the primary detection of gastric cancer due to its low sensitivity. FDG-PET shows, however, slightly better results in the evaluation of lymph node metastases in gastric cancer compared to CT and could have therefore a role in the preoperative staging. Improvement in accuracy could be achieved by using PET/CT or other PET tracers than FDG, but these modalities need further investigation. FDG-PET, however, adequately detects therapy responders at an early stage following neoadjuvant chemotherapy.

Clinical value of whole-body FDG-PET for recurrent gastric cancer: a multicenter study

OBJECTIVE

The purpose of this multicenter study was to evaluate the clinical usefulness of positron emission tomography (PET) using (18)F-fluorodeoxyglucose (FDG) for suspected recurrent gastric cancer.

METHODS

We performed a retrospective review of 92 consecutive patients who underwent PET [either integrated PET/computed tomography (CT) or manual fusion of dedicated PET and CT] scans for post-treatment surveillance of gastric cancer between June 2006 and December 2007. Of these patients, 46 patients were suspected of recurrence by other imaging modalities (Group A), 19 patients were suspected of recurrence by tumor markers without definite findings (Group B) and the remaining 27 patients underwent a PET scan without evidence of recurrence (Group C). The diagnostic performance and prevalence of the clinical impact of FDG-PET were analyzed.

RESULTS

Recurrence of gastric cancer was confirmed in 31 patients (67%) in Group A, in 11 patients (58%) in Group B and in 2 patients (7%) in Group C. In addition, colon cancer (n = 3), lung cancer (n = 1) and pulmonary carcinoid (n = 1) were identified in five patients (5%). In patient-basis, the sensitivity, specificity and diagnostic accuracy of PET for recurrence were 81%, 87% and 83%, respectively, in Group A, 73%, 88% and 79%, respectively, in Group B and 50%, 88% and 85%, respectively, in Group C. Therapeutic management was influenced by PET results in 22 patients (48%) in Group A, in 8 patients (42%) in Group B and in 2 patients (7%) in Group C, including cases in which PET was helpful for detecting second primary cancer.

CONCLUSIONS

PET with FDG yielded useful information in patients with suspected recurrent gastric cancer, especially when recurrence was suspected in the clinical setting.

The role of PET/CT in detection of gastric cancer recurrence

Background

In the course of surveillance of gastric cancer recurrence after curative resection, contrast CT scan is used in general. However, new findings from CT scan are not always confirmatory for the recurrence. In this case, we usually use short-term follow up strategy or therapeutic intervention with clinical decision. Recently, the use of fusion Positron Emission Tomography/Computed Tomography (PET/CT) is increasing. The purpose of this study is to evaluate the efficacy and usefulness of PET/CT for detecting recurrence of gastric cancer after curative resection.

Methods

Fifty two patients who received curative resection of gastric cancer and had undergone PET/CT and contrast CT for surveillance of recurrence until Dec 2006 in Seoul National University Hospital were analyzed retrospectively. Recurrence of gastric cancer was validated by histologic confirmation (n = 17) or serial contrast CT follow up with at least 5 month interval (n = 35). McNemar's test and Fisher's exact test were used to evaluate sensitivity and specificity of PET/CT and contrast CT.

Results

Of 52 patients, 38 patients were confirmed as recurrence. The sensitivity was 68.4% (26/38) for PET/CT and 89.4% (34/38) for contrast CT (p = 0.057). The specificity was 71.4% (10/14) and 64.2% (9/14), respectively (p = 1.0). In terms of the recurred sites, the sensitivity and specificity of PET/CT were similar to those of contrast CT in all sites except peritoneum. Contrast CT was more sensitive than PET/CT (p = 0.039) for detecting peritoneal seeding. Additional PET/CT on contrast CT showed no further increase of positive predictive value regardless of sites. Among 13 patients whose image findings between two methods were discordant and tissue confirmation was difficult, the treatment decision was made in 7 patients based on PET/CT, showing the final diagnostic accuracy of 42.8% (3/7).

Conclusion

PET/CT was as sensitive and specific as contrast CT in detection of recurred gastric cancer except peritoneal seeding. However, additional PET/CT on contrast CT did not increase diagnostic accuracy in detection of recurred gastric cancer. Further studies are warranted to validate the role of PET/CT in detection of gastric cancer recurrence.

Does PET-CT scan have a role prior to radical re-resection for incidental gallbladder cancer?

BACKGROUND

Radical re-resection is offered to patients with non-metastatic, invasive, incidental gallbladder cancer. Data evaluating (18)F-fluorodeoxyglucose positron emission tomography-computed tomography ((18)F-FDG PET-CT) in patients with incidental gallbladder cancer is sparse.

AIM

To evaluate the efficacy of integrated (18)F-FDG PET-CT in determining occult metastatic or residual local-regional disease in patients with incidental gallbladder cancer.

METHODS

Patients referred with incidental gallbladder cancer for radical re-resection were evaluated using multidetector computed tomography (MDCT) and PET-CT. Based on preoperative imaging, 24 out of 92 patients were found suitable for surgery. The two imaging modalities were evaluated with respect to residual and resectable disease.

RESULTS

In determining residual disease, MDCT had a sensitivity and positive predictive value (PPV) of 42.8%, each, while PET-CT had a sensitivity and PPV of 28.5 and 20%, respectively. In determining resectability, MDCT had a sensitivity, PPV, and accuracy of 100, 87.5, and 87.5%, respectively, as compared to PET-CT (sensitivity=100%, PPV=91.3%, accuracy=91.6%).

CONCLUSIONS

From our study, it appears that in patients with incidental gall bladder cancer without metastatic disease, PET-CT and MDCT seem to have roles complementing each other. PET-CT was able to detect occult metastatic or residual local-regional disease in some of these patients, and seems to be useful in the preoperative diagnostic algorithm of patients whose MDCT is normal or indicates locally advanced disease.

Gastric distension by ingesting food is useful in the evaluation of primary gastric cancer by FDG PET

Gastric carcinoma is the second leading cause of cancer-related death worldwide. Detection and surgical resection of gastric cancer in the early stage provides the only hope for improved survival in patients with gastric cancer. Positron emission tomography (PET) with F-18 2-deoxy-2-fluoro-D-glucose (FDG) has been shown to be essential in the evaluation of a variety of malignancies. However, conventional FDG PET has limited value for detecting a primary tumor of the stomach, mostly because of the relatively high levels of physiological uptake by the contracted stomach. We report 3 cases of primary gastric carcinomas detected successfully by FDG PET after the ingestion of food. The PET images of the stomach after ingesting food were compared with the routine fasting-state whole-body PET images for each patient. When the stomach was distended by food, the malignant lesions were more discernible. These cases indicate that gastric distension by ingesting food may be a simple method that can help to detect a primary gastric malignancy by FDG PET.

Focal F-18 FDG Uptake Mimicking Malignant Gastric Localizations Disappearing After Water Ingestion on PET/CT Images

Diffuse, increased gastric wall F-18 FDG uptake is widely observed during PET/CT examinations, frequently unrelated to malignant findings, but simply caused by inflammatory disease, physiological emptying, or visceral thickening. Hence, elevated F-18 FDG gastric uptake can lead to equivocal misinterpretation, especially in patients with known gastric malignant disease, at posttherapy reevaluation. Gastric wall contraction can increase F-18 FDG uptake, especially for a remnant stomach, increasing the percentage of false-positive results with a direct impact on therapeutic management. One field PET/CT acquisition centered on the hypochondrial regions a few minutes after water ingestion should be performed routinely if standard images are doubtful (increased tracer uptake and visceral thickening) to differentiate benign from malignant uptake.

Follow-up of gastric cancer: a review

Although there is broad agreement in the staging, classification, and surgery for gastric cancer, there is no consensus regarding follow-up after gastrectomy. Follow-up varies from investigations on clinical suspicion of relapse to intensive investigations to detect recurrences early, assuming that this improves survival and quality of life. Advanced gastric cancers recur mainly by locoregional recurrence or distant metastasis. Local recurrences detected at endoscopy or on computed tomography (CT) are invariably incurable. For early gastric cancers, endoscopy can detect new primaries, but the incidence of these tumors is low, and many thousands of procedures are required to detect each operable case. CT is much better at detecting liver metastasis and, although these are usually multiple and unresectable, there are several reports of good survival following liver resection for isolated metastasis. Tumor markers have been used with some success to detect subclinical recurrences and could be used to target more invasive or expensive procedures. In chemotherapy, many newer agents are promising significantly improved survival, but again, the evidence for greater benefit when administered prior to the patient becoming symptomatic is lacking. Overall, it appears that follow-up policy is as much decided by the wealth and facilities of the institution as by any significant evidence base. Although the early detection of recurrent cancer is an emotive issue for both patients and surgeons, considering the amount of time and money invested in follow-up, and the lack of evidence of efficacy, a randomized controlled trial of intensive follow-up is required.

Treatment for isolated loco-regional recurrence of gastric adenocarcinoma: does surgery play a role?

AIM

To evaluate the role of surgical treatment for isolated loco-regional recurrences of operated gastric adenocarcinoma.

METHODS

Among the 837 patients operated for gastric adenocarcinoma between December 1979 and April 2004, 713 (85%) underwent resection with curative intent. A retrospective review of a prospectively collected gastric cancer database was carried out. Overall recurrence rate was 44% (315 cases), with 75% occurring within the first 2 years from the operation. Isolated L-R recurrences were observed in 38 (12%) patients. Symptomatic lesions were observed in 27 (71%).

RESULTS

Six (16%) patients were macroscopically resected with curative intent. The recurrence was located in the gastric stump after a STG in three patients, in the esophagojejunal anastomosis after a TG in two patients and in the gastric bed after a TG in one patient. Surgical procedures consisted of three secondary TG, two esophagojejunal resection and one excision of an extraluminal recurrence. Postoperative complications occurred in two patients (33%), including one anastomotic leakage and one hemorrhage. The latter patient died of sepsis 35 d after the surgery (mortality rate 17%). All patients died of recurrent gastric cancer: 2 within 1 year from surgery (8 and 11 mo, respectively), 2 after 16 and 17 mo respectively and 1 after 28 mo from the second operation.

CONCLUSION

Surgery plays a very limited role in the treatment for isolated loco-regional recurrence of gastric adenocarcinoma.

Recurrencia de un carcinoma gástrico de células en anillo de sello demostrada por PET-FDG

OBJECTIVE

To present the case report of a patient with undifferentiated and diffuse signet-ring cell gastric carcinoma in which FDG-PET evidenced recurrent disease.

MATERIALS AND METHODS

The patient was diagnosed of a stage III gastric carcinoma in 1994 and was treated with a subtotal gastrectomy. In February 2003, recurrent disease was detected in mediastinal and left supraclavicular lymph nodes. The patient was treated with chemotherapy and radiotherapy, reaching a complete response. After 6 months free of disease, he presented an elevation of the tumor markers with negative results in conventional imaging methods (upper digestive endoscopy, bone scintigraphy, and CT). An FDG-PET scan was performed to rule out recurrent disease.

RESULTS

FDG-PET detected pathologic findings suggestive of malignant disease in right supraclavicular and mediastinal lymph nodes. These findings were confirmed by clinical follow-up and with another CT scan performed 4 months later.

CONCLUSIONS

In this case report we stress the importance of early recurrence by FDG-PET in a non-intestinal gastric carcinoma. This is of interest given the greater difficulty to detect mucous secreting and/or producing carcinomas with the PET-FDG.

Gastrointestinal uptake of FDG after N-butylscopolamine or omeprazole treatment in the rat

OBJECTIVE

Gastrointestinal (GI) uptake of 2-[18F]-fluoro-2-deoxy-D-glucose (FDG) is frequently observed in whole-body positron emission tomography (PET) images. Such physiological uptake may interfere with accurate interpretation. The aim of the present study was to determine whether physiological gastrointestinal FDG uptake can be decreased by means of an antiperistaltic agent, N-butylscopolamine, or a gastric secretion inhibitor, omeprazole.

METHODS

Sprague-Dawley rats were divided into three groups: omeprazole-treated (n = 6), N-butylscopolamine-treated (n = 7), and control group (n = 6). The rats in the omeprazole-treated group were administered omeprazole (1.0 mg/kg) intravenously 45 minutes before FDG injection. The rats in the N-butylscopolamine-treated group were administered N-butylscopolamine (1.0 mg/kg) intramuscularly 10 minutes before FDG injection. Sixty minutes after FDG injection under overnight fasting state, the gastrointestinal tissues were excised and weighed to determine the radioactivity of 18F using a gamma counter.

RESULTS

The mean values of FDG uptake in the esophagus, stomach, small intestine, cecum and colon of the N-butylscopolamine-treated group vs. the omeprazole-treated group were 148% vs. 162%, 109% vs. 113%, 113% vs. 88%, 102% vs. 85%, 105% vs. 70% of the control group, respectively. There were no statistical differences in FDG uptake rate in the esophagus, stomach, or cecum among the three groups. FDG uptake rates in the small intestine and colon of the omeprazole-treated group were significantly lower than those in the control group.

CONCLUSION

Physiological FDG uptake in the GI tract was not decreased by the administration of N-butylscopolamine. Omeprazole was effective in decreasing FDG uptake in the small intestine and colon. Omeprazole has a potential to decrease FDG uptake rate in a limited part of the GI tract.

The value of vesicant 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) in gastric malignancies

AIM

The value of vesicant 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) in the detection and staging of primary gastric malignancies was studied prospectively.

METHODS

Thirty-eight patients with suspected gastric tumour were imaged with three-dimensional PET after the injection of 18F-FDG. During the PET study, vesicant was given orally in order to extend the stomach with CO(2) gas. Surgical operation (n=31) or gastric endoscopy with biopsy (n=7) was undertaken 3-26 days after the PET study. The PET results were compared with clinical (computed tomography/magnetic resonance imaging/ultrasound), surgical and histological staging.

RESULTS

PET correctly diagnosed 83.3% of primary malignant (25/30) and benign (7/8) lesions, and corrected 11 clinically and five surgically mis-staged cases. Five primaries were false-negatives in quantitative analysis, but qualitative PET readings revealed positive lymph nodes, thereby providing a correct diagnosis in two of the five. PET misdiagnosed seven N1, one N2 and one false-positive case. The focal uptake of 18F-FDG was correlated with the differentiation, size and depth of invasion of the gastric tumours.

CONCLUSIONS

18F-FDG PET is useful for the detection and staging of primary gastric malignancies, and the administration of vesicant may improve the diagnostic confidence.

Improvement in preoperative staging of gastric adenocarcinoma with positron emission tomography

BACKGROUND

Positron emission tomography (PET) with 18- fluorodeoxyglucose (FDG) has been used to both detect and stage a variety of malignancies. The current study examined the value of PET for preoperative staging of gastric adenocarcinoma.

METHODS

Sixty-eight patients (49 males and 19 females) with gastric adenocarcinoma, who were referred for preoperative FDG-PET scans, were enrolled in this study. The patients underwent spiral-computed tomography (CT) within 1 week of referral. The final diagnosis in all patients was made by histologic and surgical findings. For quantitative PET analysis, the regional tumor FDG uptake was measured by the standardized uptake value (SUV).

RESULTS

For the primary tumor of a gastric adenocarcinoma, PET demonstrated an increased uptake in 64 of 68 patients (sensitivity, 94%), with a mean SUV of 7.0 (range, 0.9-27.7). A comparison of FDG uptake and clinicopathologic features showed significant association between FDG uptake and macroscopic type, tumor size, lymph node metastasis, histologic type, and TNM stage. The PET scan had a similar accuracy with that of CT for diagnosing local and distant lymph node metastases as well as peritoneal status. In assessing local lymph node status, however, PET had a higher specificity than CT (92% vs. 62%, P = 0.000). Moreover, PET had additional diagnostic value in 10 (15%) of 68 patients by upstaging 4 (6%) and downstaging 6 (9%) patients. PET combined with CT was more accurate for preoperative staging than either modality alone (66% vs. 51%, 66% vs. 47%, respectively; P = 0.002).

CONCLUSIONS

FDG-PET improves the preoperative TNM staging of gastric adenocarcinoma. Based on its superior specificity, FDG-PET can facilitate the selection of patients for a curative resection by confirming a nodal status identified by CT.

PET imaging in assessing gastrointestinal tumors

The clinical usefulness of FDG-PET imaging is now firmly established in various situations, such as the preoperative staging of esophageal cancer and recurrent colorectal carcinoma and the detection and staging of recurrent colorectal cancer when there is a clinical or biologic suspicion with inconclusive conventional findings. Encouraging results were obtained in the evaluation of the therapeutic response of various gastrointestinal malignancies, either during the treatment or after its completion. There is no firm consensus regarding its role in pancreatic cancer, either proved or suspected, but it may be valuable in selected clinical situations. Its role seems fairly limited in patients with hepatocellular carcinoma, although PET findings may have prognostic implications. Evaluation of cholangiocarcinoma is an emerging indication, albeit with limited data to date. Finally, PET/CT is very likely to enhance the role of FDG imaging further in the work-up of patients with gastrointestinal tumors.

[18F]Fluoro-2-deoxy-d-glucose Positron Emission Tomography Detects Gastric Carcinoma in an Early Stage in an Asymptomatic E-Cadherin Mutation Carrier

PURPOSE

Autosomal dominant hereditary diffuse gastric cancer (HDGC) is caused by germ-line E-cadherin (CDH1) gene mutations. Early detection of cancer in carriers is difficult because HDGC escapes endoscopic detection. We hypothesized that the glucose metabolism is enhanced in HDGC and that this can be detected with [18F]fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET).

EXPERIMENTAL DESIGN AND RESULTS

An asymptomatic twenty-eight year-old female was seen at our outpatient clinic because of a request for screening on HDGC. Her father and younger sister died of diffuse gastric cancer, at the ages of 52 and 27, respectively. Mutational analysis of the CDH1 gene in this patient demonstrated a novel heterozygous splice-site mutation in exon 8 (1135delACGGTAATinsTTAGA). Upper gastrointestinal endoscopies revealed no macroscopic abnormalities, but one of the 40 random biopsy specimens showed well-differentiated signet-cell carcinoma. A FDG-PET scan demonstrated two spots of FDG accumulation, one located in the proximal part of the stomach and the second in the region of the pylorus. A total gastrectomy was performed and microscopic examination showed focal localization of intramucosal adenocarcinoma of the signet-cell type in the cardiac and antrum area. Most notably, the localization of the FDG accumulation matched the localization of the carcinoma.

CONCLUSIONS

We present an asymptomatic patient from a HDGC family carrying a novel CDH1 mutation in whom FDG-PET scanning facilitated early detection of HDGC. This calls for further investigation of the role of FDG-PET scan as a screening modality in HDGC.