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Journal Watch - July 2022 (2)

Incidence of pancreatic cancer during long‐term follow‐up in patients with incidental pancreatic cysts smaller than 2 cm

Masoud Nakhaei · Mathew Bligh · Victoria Chernyak · Abraham F. Bezuidenhout · Alexander Brook · Olga R. Brook

Eur Radiol 32, 3369–3376 (2022) doi: 10.1007/s00330-021-08428-1

 

Pancreatic cysts are frequent finding in patients undergoing cross-sectional imaging for non-pancreatic reasons, with prevalence ranging from 2.6% (on CT) to 20% (on MRI) [1], [2]. Most of these cysts reveal to be intraductal papillary mucinous neoplasms (IPMN), with low risk of malignant transformation [3]–[5]. Fukuoka guidelines suggest that small (less than 2 cm) cysts without high-risk stigmata, can be followed up with imaging [4], [5]. However, there is no consensus on how to follow up these cysts. The existing guidelines available on this topic propose different follow-up protocols, such as terminating follow-up after a time interval of dimensional stability or stopping follow-up only when the patient is no longer suitable for surgery[6]–[9]. The cause of this lack of consensus is to be referred to the fact that there is no definite data on the incidence of PDAC in patients with pancreatic cysts of these dimensions.

The objective of this study [10] is to evaluate long-term malignancy risk and mortality of small pancreatic cysts in asymptomatic patients with the purpose of optimizing follow-up protocols in this population.

In a retrospective multicenter study, 267 asymptomatic patients from Beth Israel Deaconess Medical Center (Boston, MA) with incidental MRI finding of pancreatic cysts, with diameter ranging from 5 to 20 mm, were enrolled in the “small pancreatic cyst” group. The selected patients had at least two abdominal MRIs at least six months apart. Patients with history of pancreatitis were excluded, as it is considered a risk factor for PDAC. 1459 patients from Montefiore Medical Center (Bronx, NY) with matching age decade, imaging modality (MRI vs. CT) and year of the index date formed the “no cyst” group. Patients with a diagnosis of any pancreatic neoplasm within 5 years before the date of the index study were excluded.

Endpoints of the study included mortality and incidence of pancreatic cancer; in case of pancreatic cancer occurrence, it was noted weather it developed in the same location of the cyst or from a different area.

In the “small pancreatic cyst” cohort, 0.7% of patients developed pancreatic cancer. 0.4% of patients developed low-grade dysplasia. Mortality was 21%, 4% of which was due to pancreatic cancer. In the “no pancreatic cyst” group, 1.2% of patients developed pancreatic cancer; mortality was 26%. The difference between the incidence of PDAC in the two groups did not appear to be statistically significant. During the radiological follow-up (mean 6.1 ± 4.2 years) the yearly growth rate was 0.0003± 1.8 mm/year or 0.7 ± 20.9%/year.

Interestingly, the most clinically relevant result of this study is that none of the PDAC diagnosed during the follow-up originated from the followed cysts.

The importance of this study resides in the fact that not only it evaluates the incidence of PDAC in patients with small pancreatic cysts but compares it with the incidence of PDAC in patients without cysts, proving that the presence of small cysts does not act as an additive risk factor in the general population.

These results are in line with a previously published paper from Chernyak and co-workers [11], where the incidence of PDAC less then 2 cm did not differ significantly from patients without cysts. On the other hand, larger cysts increase the risk by three times.

The retrospective design of the study may have caused some patient selection biases, the limited clinical data mentioned in the indication of the imaging study does not allow to completely rule out risk factors for PDAC, such as pancreatitis. Moreover, the enrolment of patients in the two groups was only based on the report, thus, patients with pancreatic cysts may have been either excluded from the “cyst group” or included in the “no cyst group”.

In conclusion, the results of this study show that the presence of small pancreatic cysts does not represent a risk factor for PDAC, since its incidence over a 6 years follow up period is similar in patients with less than 2 cm pancreatic cysts and patients without pancreatic cysts.

Therefore, the frequency and duration of follow-up proposed by existing guidelines could be reduced, thus decreasing the induced patient anxiety and the burden on healthcare system.

 

References:

 

  1. M.-L. Kromrey et al., “Prospective study on the incidence, prevalence and 5-year pancreatic-related mortality of pancreatic cysts in a population-based study,” Gut, vol. 67, no. 1, pp. 138–145, Jan. 2018, doi: 10.1136/gutjnl-2016-313127.
  2. O. R. Brook et al., “Delayed Growth in Incidental Pancreatic Cysts: Are the Current American College of Radiology Recommendations for Follow-up Appropriate?,” Radiology, vol. 278, no. 3, pp. 752–761, Mar. 2016, doi: 10.1148/radiol.2015140972.
  3. Y. Yamada, H. Mori, S. Matsumoto, N. Kamei, and N. Hongo, “Invasive Carcinomas Derived From Intraductal Papillary Mucinous Neoplasms of the Pancreas,” Journal of Computer Assisted Tomography, vol. 30, no. 6, pp. 885–890, Nov. 2006, doi: 10.1097/01.rct.0000220801.76276.0f.
  4. M. Tanaka et al., “Revisions of international consensus Fukuoka guidelines for the management of IPMN of the pancreas,” Pancreatology, vol. 17, no. 5, pp. 738–753, Sep. 2017, doi: 10.1016/j.pan.2017.07.007.
  5. M. Tanaka et al., “International consensus guidelines 2012 for the management of IPMN and MCN of the pancreas,” Pancreatology, vol. 12, no. 3, pp. 183–197, May 2012, doi: 10.1016/j.pan.2012.04.004.
  6. A. J. Megibow et al., “Management of Incidental Pancreatic Cysts: A White Paper of the ACR Incidental Findings Committee,” Journal of the American College of Radiology, vol. 14, no. 7, pp. 911–923, Jul. 2017, doi: 10.1016/j.jacr.2017.03.010.
  7. S. S. Vege et al., “American Gastroenterological Association Institute Guideline on the Diagnosis and Management of Asymptomatic Neoplastic Pancreatic Cysts,” Gastroenterology, vol. 148, no. 4, pp. 819–822, Apr. 2015, doi: 10.1053/j.gastro.2015.01.015.
  8. G. H. Elta, B. K. Enestvedt, B. G. Sauer, and A. M. Lennon, “ACG Clinical Guideline: Diagnosis and Management of Pancreatic Cysts,” American Journal of Gastroenterology, vol. 113, no. 4, pp. 464–479, Apr. 2018, doi: 10.1038/ajg.2018.14.
  9. “European evidence-based guidelines on pancreatic cystic neoplasms,” Gut, vol. 67, no. 5, pp. 789–804, May 2018, doi: 10.1136/gutjnl-2018-316027.
  10. M. Nakhaei, M. Bligh, V. Chernyak, A. F. Bezuidenhout, A. Brook, and O. R. Brook, “Incidence of pancreatic cancer during long-term follow-up in patients with incidental pancreatic cysts smaller than 2 cm,” European Radiology, vol. 32, no. 5, pp. 3369–3376, May 2022, doi: 10.1007/s00330-021-08428-1.
  11. V. Chernyak, M. Flusberg, L. B. Haramati, A. M. Rozenblit, and E. Bellin, “Incidental Pancreatic Cystic Lesions: Is There a Relationship with the Development of Pancreatic Adenocarcinoma and All-Cause Mortality?,” Radiology, vol. 274, no. 1, pp. 161–169, Jan. 2015, doi: 10.1148/radiol.14140796.

 

Dr. Sara Belcastro is a first-year radiology resident on the “Sapienza, University of Rome” training scheme in Italy. She completed her undergraduate medical degree at “Sapienza, University of Rome” in 2021. She joined the Medical Imaging Department in the same year where she is undertaking training in diagnostic and interventional radiology, with particular interest towards abdominal imaging.

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