Preoperative Nodal 18F-FDG Avidity Rather than Primary Tumor Avidity Determines the Prognosis of Patients with Advanced Gastric Cancer

Patient metabolic profile defined by liver and muscle 18F-FDG PET avidity is independently associated with overall survival in gastric cancer

BACKGROUND

PET-CT-based patient metabolic profiling is a novel concept to incorporate patient-specific metabolism into gastric cancer care.

METHODS

Staging PET-CTs, demographics, and clinicopathologic variables of gastric cancer patients were obtained from a prospectively maintained institutional database. PET-CT avidity was measured in tumor, liver, spleen, four paired muscles, and two paired fat areas in each patient. The liver to rectus femoris (LRF) ratio was defined as the ratio of SUVmean of liver to the average SUVmean of the bilateral rectus femoris muscles. Kaplan-Meier and Cox-proportional hazards models were used to identify the impact of LRF ratio on OS.

RESULTS

Two hundred and one patients with distal gastroesophageal (48%) or gastric (52%) adenocarcinoma were included. Median age was 65 years, and 146 (73%) were male. On univariate analysis, rectus femoris PET-CT avidity and LRF ratio were significantly associated with overall survival (p < 0.05). LRF ratio was significantly higher in males, early-stage cancer, patients with an ECOG 0 or 1 performance status, patients with albumin > 3.5 mg/dL, and those with moderately differentiated tumor histology. In multivariable regression, gastric cancer stage, albumin, and LRF ratio were significant independent predictors of overall survival (LRF ratio HR = 0.73 (0.56-0.96); p = 0.024). Survival curves showed that the prognostic impact of LRF was associated with metastatic gastric cancer (p = 0.009).

CONCLUSIONS

Elevated LRF ratio, a patient-specific PET-CT-based metabolic parameter, was independently associated with an improvement in OS in patients with metastatic gastric cancer. With prospective validation, LRF ratio may be a useful, host-specific metabolic parameter for prognostication in gastric cancer.

18F-fluorodeoxyglucose uptake in advanced gastric cancer correlates with histopathological subtypes and volume of tumor stroma

PURPOSE

The aim of this study was to investigate the correlation between preoperative ¹⁸F-fluorodeoxyglucose (FDG) uptake and histological subtypes, amount of tumor stroma in advanced gastric cancer (GC), and clinical outcomes.

METHODS

We evaluated 56 patients (male/female, 42:14; mean age, 69 years) with advanced GC who underwent surgical resection at our institution and positron emission tomography-computed tomography with 18F-FDG prior to surgery. We used the maximum standardized uptake value (SUVmax) of the tumor and the tumor-to-liver ratio (TLR) of the SUVmax for the analysis. The SUVmax and TLR correlated with histological subtypes, immunohistochemistry (IHC) for CD34, and recurrence-free survival (RFS). Tumor stroma in GC was evaluated by CD34 expression. GCs were classified according to the Lauren and World Health Organization (WHO) classifications.

RESULTS

The average FDG uptakes (SUVmax) were 4.17% and 14.04% in diffuse and intestinal type GCs, respectively, according to the Lauren classification, and 4.17%, 13.87%, 7.70%, 9.71%, and 19.45% in the poorly cohesive, tubular, mucinous, and papillary adenocarcinomas, respectively, according to the WHO classification. The FDG uptake in diffuse type was significantly lower than that in the intestinal type (p = 0.000). The SUVmax and TLR of the CD34(+) group (mean SUVmax, 5.50; TLR, 1.56) were significantly lower than those of the CD34(-) group (mean SUVmax, 14.09; TLR, 4.09). RFS was not associated with TLR or CD34 expression.

CONCLUSION

GC, which has abundant tumor stroma characterized by high CD34 expression on IHC, shows low FDG uptake.

18F-FDG-PET/CT Imaging for Gastrointestinal Malignancies

Gastrointestinal malignancies encompass a variety of primary tumor sites, each with different staging criteria and treatment approaches. In this review we discuss technical aspects of 18F-FDG-PET/CT scanning to optimize information from both the PET and computed tomography components. Specific applications for 18F-FDG-PET/CT are summarized for initial staging and follow-up of the major disease sites, including esophagus, stomach, hepatobiliary system, pancreas, colon, rectum, and anus.

Opportunities in cancer imaging: a review of oesophageal, gastric and colorectal malignancies

The incidence of gastrointestinal (GI) malignancy is increasing worldwide. In particular, there is a concerning rise in incidence of GI cancer in younger adults. Direct endoscopic visualisation of luminal tumour sites requires invasive procedures, which are associated with certain risks, but remain necessary because of limitations in current imaging techniques and the continuing need to obtain tissue for diagnosis and genetic analysis; however, management of GI cancer is increasingly reliant on non-invasive, radiological imaging to diagnose, stage, and treat these malignancies. Oesophageal, gastric, and colorectal malignancies require specialist investigation and treatment due to the complex nature of the anatomy, biology, and subsequent treatment strategies. As cancer imaging techniques develop, many opportunities to improve tumour detection, diagnostic accuracy and treatment monitoring present themselves. This review article aims to report current imaging practice, advances in various radiological modalities in relation to GI luminal tumour sites and describes opportunities for GI radiologists to improve patient outcomes.

Staging FDG PET-CT changes management in patients with gastric adenocarcinoma who are eligible for radical treatment

AIM

18-fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET-CT) is valuable in the management of patients with oesophageal cancer, but a role in gastric cancer staging is debated. Our aim was to review the role of FDG PET-CT in a large gastric cancer cohort in a tertiary UK centre.

METHODS

We retrospectively reviewed data from 330 patients presenting with gastric adenocarcinoma between March 2014 and December 2016 of whom 105 underwent pre-treatment staging FDG PET-CT scans. FDG PET-CT scans were graded qualitatively and quantitatively (SUVmax) and compared with staging diagnostic CT and operative pathology results (n = 30) in those undergoing resection.

RESULTS

Of the 105 patients (74 M, median age 73 years) 86% of primary tumours were metabolically active (uptake greater than normal stomach) on FDG PET-CT [41/44 (93%) of the intestinal histological subtype (SUVmax 14.1 ± 1.3) compared to 36/46 (78%) of non-intestinal types (SUVmax 9.0 ± 0.9), p = 0.005]. FDG PET-CT upstaged nodal or metastastic staging of 20 patients (19%; 13 intestinal, 6 non-intestinal, 1 not reported), with 17 showing distant metastases not evident on other imaging. On histological analysis, available in 30 patients, FDG PET-CT showed low sensitivity (40%) but higher specificity (73%) for nodal involvement.

CONCLUSION

FDG PET-CT provides new information in a clinically useful proportion of patients, which leads to changes in treatment strategy, most frequently by detecting previously unidentified metastases, particularly in those with intestinal-type tumours.

Metabolic Characteristics and Diagnostic Contribution of 18F-FDG PET/CT in Gastric Carcinomas

Objectives:

The aim of this study was to evaluate ¹⁸F-fluoro-2-deoxy-glucose (FDG) uptake patterns in primary tumors and metastatic lesions, and also to assess the diagnostic contribution of positron emission tomography/computed tomography (PET/CT) in the initial staging of gastric cancer (GC).

Methods:

The total number of 341 patients with GC were included in this study. All ¹⁸F-FDG PET/CT imagings were performed for initial staging. The maximum standardized uptake value (SUV_max) of primary tumor, obtained from ¹⁸F-FDG PET/CT imaging was compared between subtypes of GC.

Results:

Mean SUV_max of 339 patients’ primary tumor was 12.9±8.6. The highest mean SUV_max was detected in patients with medullary subtype GC (17.8±9.9) while the lowest mean SUV_max (9.7±7.6) was seen in signet ring cell carcinoma (SRCC). The primary mean SUV_max was found statistically higher in tubular adenocarcinoma (TAC) group than SRCC group (p<0.001). Higher SUV_max values were found statistically significantly correlated with advanced age (aged ≥60) and increased tumor size (>3 cm) in patients with TAC (p=0.03). Primary tumor SUV_max was found statistically higher in regional lymph node (RLN) positive patients than in RLN negative patients in TAC and SRCC groups (p<0.001 and p=0.012, respectivelly). Also, in patients with SRCC, SUV_max was significantly higher in the distant metastatic group than in the group without metastasis (p=0.025).

Conclusion:

Increased primary tumor SUV_max was associated with some of clinical parameters such as age and RLN metastasis in patients with TAC. However, there was no relationship between distant metastatic state and primary tumor ¹⁸F-FDG uptake in TAC. However, high SUV_max of primary tumor in SRCC was associated with regional and distant metastasis, and primary tumor ¹⁸F-FDG uptake may be a prognostic value for this subgroup.