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Diagnosis and Management of Asymptomatic Neoplastic Pancreatic Cysts

The American Gastroenterological Association Institute Guideline on the Diagnosis and Management of Asymptomatic Neoplastic Pancreatic Cysts

 

Updated recommendations developed by the American Gastroenterological Association (AGA) on management of asymptomatic pancreatic neoplastic cysts call for a conservative approach in many cases as most such cysts are not cancerous. Approximately 15% of patients undergoing abdominal magnetic resonance imaging (MRI) for other indications harbor unsuspected pancreatic cysts. The incidence of pancreatic cysts in the US population increases with age and may be as common as 25% in those older than 70 years. The management of patients with an incidentally detected pancreatic cyst poses a significant challenge. In an effort to provide a strategy by which clinicians may identify the small minority of cysts with early invasive cancer or high-grade dysplasia – or those which will develop them in the near future – the AGA developeded 10 recommendations, although listed as “conditional” because of very low-quality evidence.

 

The AGA guidelines pertain only to asymptomatic pancreatic neoplastic cysts. The impact of symptoms on the management of cysts was not assessed, and this guideline does not consider some neoplastic lesions such as solid papillary neoplasms, cystic degeneration of adenocarcinomas, neuroendocrine tumors, and main duct intraductal papillary mucinous neoplasms (IPMNs) without side branch involvement, as identification of these neoplasms may be less challenging and the accepted approach is surgical resection if the patient is a suitable candidate.

 

 

The overall risk that an incidental pancreatic cyst is malignant is very low. The AGA estimates that a cyst seen incidentally on MRI has a 10 in 100,000 chance of being a mucinous invasive malignancy and a 17 in 100,000 chance of being a ductal cancer. MRI is the preferred surveillance imaging modality, because MRI does not expose the patient to radiation, and it is better able to demonstrate the structural relationship between the pancreatic duct and associated cyst than CT.

 

  • The AGA suggests that patients with pancreatic cysts less than 3 cm without a solid component or a dilated pancreatic duct undergo MRI for surveillance in 1 year and then every 2 years for a total of 5 years if there is no change in cyst size or characteristics.
  • The AGA suggests that pancreatic cysts with at least 2 high-risk features such as size ≥3 cm, a dilated main pancreatic duct, or the presence of an associated solid component, should be examined with endoscopic ultrasonography-guided fine-needle aspiration (EUS-FNA). The relative increase in risk of malignancy in the presence of high-risk features may be substantial but because the baseline risk is so low, the absolute effect of these features is modest.
  • The AGA suggests that patients without concerning EUS-FNA results should undergo MRI surveillance after 1 year and then every 2 years to ensure no change in risk of malignancy. The negative predictive value of unremarkable EUS-FNA results is very high and this in a setting with a very low risk of associated malignancy.
  • The AGA suggests that significant changes in the characteristics of the cyst including the development of a solid component, increasing size of the pancreatic duct, and/or diameter ≥3 cm, are indications for EUS-FNA.
  • The AGA suggests against continued surveillance of pancreatic cysts if there has been no significant change in the characteristics of the cyst after 5 years of surveillance or if the patient is no longer a surgical candidate.
  • The AGA suggests that patients with both a solid component and a dilated pancreatic duct and/or concerning features on EUS and FNA should undergo surgery to reduce the risk of mortality from carcinoma. Surgery is likely to be most beneficial in cases of cyst resection of high-grade dysplasia, thereby preventing malignancy. Since it is clear from other cancers that not all high-grade dysplasia progress, the proportion of patients who truly benefit from surgery is unclear even in this high-risk group.
  • The AGA recommends that if surgery is considered for a pancreatic cyst, patients are referred to a center with demonstrated expertise in pancreatic surgery.
  • The AGA suggests that patients with invasive cancer or dysplasia in a cyst that has been surgically resected should undergo MRI surveillance of any remaining pancreas every 2 years.
  • The AGA recommends against routine surveillance of pancreatic cysts without high-grade dysplasia or malignancy at surgical resection.
  • The AGA recommends that before starting any pancreatic cyst surveillance program, patients should have a clear understanding of programmatic risks and benefits.
Three commentaries in the April 2015 edition of Gastroenterology are worthwhile reading (April 2015, Volume 148, Issue 4, p669-862, e1-e16). One paper questions whether even small pancreatic cysts without concerning features have a high risk of malignancy. The clinician taking care of patients with pancreatic cysts is advised to be cautious in applying this new guideline.
In Summary – Issues Related to the Conduct of Surveillance
  1. The AGA recommends that before starting any pancreatic cyst surveillance program, patients should have a clear understanding of programmatic risks and benefits.
  2. The AGA suggests that patients with pancreatic cysts less than 3 cm without a solid component or a dilated pancreatic duct undergo MRI for surveillance in 1 year and then every 2 years for a total of 5 years if there is no change in size or characteristics.
  3. The AGA suggests that pancreatic cysts with at least 2 high-risk features, such as size ‡3 cm, a dilated main pancreatic duct, or the presence of an associated solid component, should be examined with EUS-FNA.
  4. The AGA suggests that patients without concerning EUS-FNA results should undergo MRI surveillance after 1 year and then every 2 years to ensure no change in risk of malignancy.
  5. The AGA suggests that significant changes in the characteristics of the cyst, including the development of a solid component, increasing size of the pancreatic duct, and/or diameter ‡3 cm, are indications for EUS-FNA.
  6. The AGA suggests against continued surveillance of pancreatic cysts if there has been no significant change in the characteristics of the cyst after 5 years of surveillance or if the patient is no longer a surgical candidate.
  7. The AGA suggests that patients with both a solid component and a dilated pancreatic duct and/or concerning features on EUS and FNA should undergo surgery to reduce the risk of mortality from carcinoma.
  8. The AGA recommends that if surgery is considered for a pancreatic cyst, patients are referred to a center with demonstrated expertise in pancreatic surgery.
  9. The AGA suggests that patients with invasive cancer or dysplasia in a cyst that has been surgically resected should undergo MRI surveillance of any remaining pancreas every 2 years.
  10. The AGA suggests against routine surveillance of pancreatic cysts without high-grade dysplasia or malignancy at surgical resection.
Abbreviations
EUS, endoscopic ultrasonography
FNA, fine-needle aspiration
HGD, high-grade dysplasia
IPMN, intraductal papillary mucinous neoplasm
MRI, magnetic resonance imaging
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