To the Editor:We read with interest “A comparative analysis of glucose and carcinoembryonic antigen in diagnosis of pancreatic mucinous cysts: a systematic review and meta-analysis” by Faias et al.1

Faias S, Cravo MM, Chaves P, et al. Comparative analysis of glucose and carcinoembryonic antigen in diagnosis of pancreatic mucinous cysts: a systematic review and meta-analysis. Gastrointest Endosc. Epub 2021 Apr 11.

The authors conclude that pancreatic cyst fluid (PCF) glucose is more accurate than carcinoembryonic antigen (CEA) in determining whether the lesion is mucinous. There are several limitations in the reviewed body of literature that make this conclusion suspect. One of the 5 studies did not compare glucose with surgical pathologic analysis and should not have been included in the meta-analysis, given the inclusion criteria set by the authors.2Cyst fluid glucose: an alternative to carcinoembryonic antigen for pancreatic mucinous cysts. There are insufficient data on the sensitivity and specificity of PCF glucose with the use of surgical pathologic analysis as a criterion standard. Three of the studies in the glucose group were done by a similar group of authors, and among those, 2 were done at the same center, raising a question of overlapping patients.3Carr R.A. Yip-Schneider M.T. Simpson R.E. et al.Pancreatic cyst fluid glucose: rapid, inexpensive, and accurate diagnosis of mucinous pancreatic cysts., 4Park W.G. Wu M. Bowen R. et al.Metabolomic-derived novel cyst fluid biomarkers for pancreatic cysts: glucose and kynurenine., 5Zikos T. Pham K. Bowen R. et al.Cyst fluid glucose is rapidly feasible and accurate in diagnosing mucinous pancreatic cysts. In the systematic review, the authors state that 8 studies that used CEA values other than 192 ng/mL were excluded. However, the table includes several studies for which the cutoff point for CEA level was not available or that used values other than 192 ng/mL.6Frossard J.L. Amouyal P. Amouyal G. et al.Performance of endosonography-guided fine needle aspiration and biopsy in the diagnosis of pancreatic cystic lesions.

The aim of this meta-analysis was to determine the utility of preoperative EUS-obtained PCF glucose levels for the diagnosis of a mucinous cyst. However, only 53 patients underwent EUS sampling, whereas most samples were collected during surgery. This introduces a possible selection bias, because the decision for surgery may have been based on other factors (for example, imaging findings or cytologic findings). Finally, studies need to be done to see whether the time from aspiration and freezing or thawing affects the glucose levels. For these reasons, it is hard to conclude from this meta-analysis that PCF glucose is more accurate than CEA. Larger prospective studies are clearly needed to establish the utility of PCF glucose determination in clinical practice.

Disclosure

Dr Confer is a consultant for Boston Scientific and Merit Endotek. Dr Diehl is a consultant for Olympus America, Boston Scientific, and Cook Medical. The other author disclosed no financial relationships.

References

Faias S, Cravo MM, Chaves P, et al. Comparative analysis of glucose and carcinoembryonic antigen in diagnosis of pancreatic mucinous cysts: a systematic review and meta-analysis. Gastrointest Endosc. Epub 2021 Apr 11.

Cyst fluid glucose: an alternative to carcinoembryonic antigen for pancreatic mucinous cysts.

World J Gastroenterol. 25: 2271-2278Carr R.A. Yip-Schneider M.T. Simpson R.E. et al.

Pancreatic cyst fluid glucose: rapid, inexpensive, and accurate diagnosis of mucinous pancreatic cysts.

Surgery. 163: 600-605Park W.G. Wu M. Bowen R. et al.

Metabolomic-derived novel cyst fluid biomarkers for pancreatic cysts: glucose and kynurenine.

Gastrointest Endosc. 78: 295-302.e2Zikos T. Pham K. Bowen R. et al.

Cyst fluid glucose is rapidly feasible and accurate in diagnosing mucinous pancreatic cysts.

Am J Gastroenterol. 110: 909-914Frossard J.L. Amouyal P. Amouyal G. et al.

Performance of endosonography-guided fine needle aspiration and biopsy in the diagnosis of pancreatic cystic lesions.

Am J Gastroenterol. 98: 1516-1524Article InfoIdentification

DOI: https://doi.org/10.1016/j.gie.2021.02.029

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© 2021 by the American Society for Gastrointestinal Endoscopy

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Gastrointestinal Endoscopy

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Pancreatic cystic fluid (PCF) analysis is useful to distinguish between different cyst types and to guide management. The aim of our study was to compare the diagnostic accuracy of glucose level with carcinoembryonic antigen (CEA) in PCF for mucinous cyst diagnosis.

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Gastrointestinal EndoscopyVol. 94Issue 1

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We wish to thank Confer et al1 for their interest in our recent meta-analysis comparing carcinoembryonic antigen (CEA) and cyst fluid glucose in the diagnosis of mucinous cysts.2 The growing rate of pancreatic cyst diagnosis is due to improvements in the quality and increased use of cross-sectional imaging. Better biomarkers that help to discriminate potentially malignant lesions are needed in clinical practice. Previous studies, namely, one study from our group,3 showed that cyst glucose concentration performs better than CEA to identify mucinous, potentially malignant cysts, with the need of minimal amounts of cyst fluid.

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