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. 2019 May;29(5):2490-2498.
doi: 10.1007/s00330-018-5904-2. Epub 2019 Jan 14.

Routinely staging gastric cancer with 18F-FDG PET-CT detects additional metastases and predicts early recurrence and death after surgery

John M Findlay  1   2 , Stefan Antonowicz  3 , Ashvina Segaran  3 , Jihene El Kafsi  3 , Alexa Zhang  3 , Kevin M Bradley  4 , Richard S Gillies  3 , Nicholas D Maynard  3 , Mark R Middleton  5
Affiliations

Routinely staging gastric cancer with 18F-FDG PET-CT detects additional metastases and predicts early recurrence and death after surgery

John M Findlay et al. Eur Radiol. 2019 May.

Abstract

Objectives: Fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) is typically considered to have minimal yield in gastric cancer, and so is not consistently recommended by international guidelines. However, its yield is considerable in esophageal and junctional cancer, identifying unsuspected metastases and risk-stratifying patients using metabolic nodal stage (mN). We aimed to determine the contemporary utility of routine 18F-FDG PET-CT in gastric cancer.

Methods: We routinely stage patients with non-junctional gastric cancer with PET-CT, provided initial CT does not demonstrate unequivocal metastases. We performed a retrospective study of all such patients staged in our institution from January 2007 to July 2016. Our primary endpoint was detection of incurable disease. Our secondary endpoint was disease-free survival following gastrectomy. Decision theory, economic, and predictive models were generated.

Results: The primary tumor was FDG-avid in 225/279 patients (80.6%). Seventy-two (25.8%) had FDG-avid nodes (resectable by D2 lymphadenectomy). This was not influenced by the Lauren classification. Unsuspected metastases were identified in 20 patients (7.2%). In 13 (4.7%), these would not have been otherwise identified. Decision theory and economic modeling supported routine PET-CT. Patients with FDG-avid nodes were more likely to have incurable disease (51.4% versus 15.5%; p < 0.001), and a worse prognosis if not: multivariate hazard ratio 2.19 (1.23-3.91; p = 0.008). Prognosis worsened with mN stage.

Conclusions: PET-CT appears useful when used routinely for non-junctional gastric cancer, and should be considered in international recommendations. Any extra costs appear small and offset by avoiding futile investigations and radical treatment. mN stage identifies patients at risk of early recurrence and death.

Key points: • PET-CT is typically not considered useful when staging gastric cancer. We describe a retrospective study of 279 patients routinely staged with PET-CT in the absence of metastases on CT. • The primary tumor was avid in 80% of patients. Twenty-five percent had resectable avid nodes. PET-CT identified previously unsuspected metastases in 7% of patients, which would likely not have been identified by conventional staging without PET-CT in 5%. These patients were much more likely to have avid nodes. • Beyond avoiding futile investigations and radical treatment in this 5%, we found patients with FDG-avid nodes (metabolic nodal stage, mN) to have a worse disease-free survival after gastrectomy.

Keywords: Cancer staging; Gastric cancer; Metastases; PET-CT; Prognosis.

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Conflict of interest statement

Guarantor

The scientific guarantor of this publication is John Findlay.

Conflict of interest

The authors of this manuscript declare relationships with the following companies:

MRM has the following roles to disclose:

Advisory/consulting role (payment to the individual) Amgen, BMS, GSK, Merck, Millennium, Physiomics, and Roche. Research funding (payment to the institution) from Amgen, AZ, BMS, Clovis, Eisai, GSK, Immunocore, Johnson & Johnson, Merck, Millennium, Novartis, Pfizer, Roche, and Vertex. JMF has the following roles to disclose: Unremunerated advisory role to Physiomics

Statistics and biometry

One of the authors (JMF) has significant statistical expertise.

Informed consent

Written informed consent was waived by the Institutional Review Board.

Ethical approval

Institutional Review Board approval was obtained.

Methodology

• retrospective

• diagnostic or prognostic study

• performed at one institution

Figures

Fig. 1
Fig. 1
Disease-free survival and mN stage
See this image and copyright information in PMC

References

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