COMMENTARY

Asymptomatic Pancreatic Cysts: Science Challenges Surgical Management

David A. Johnson, MD, FACG, FACP

Disclosures

September 10, 2007

Nonsurgical Management of Asymptomatic Incidental Pancreatic Cysts

Lahav M, Maor Y, Avidan B, Novis B, Bar-Meir S
Clin Gastroenterol Hepatol. 2007;5:813-817

Abstract

Branch-Duct Intraductal Papillary Mucinous Neoplasms: Observations in 145 Patients Who Underwent Resection

Rodriguez, JR, Salvia R, Crippa S, et al
Gastroenterology. 2007;133:72-79

Abstract

Editor's Note: Dr. Johnson's summary and commentary collaboratively address these 2 reports assessing the natural course of asymptomatic pancreatic cysts and their malignancy potential.

The identification of asymptomatic cystic lesions of the pancreas has become an increasing issue for patients and their treating physicians. Most of these lesions have been identified as a result of the increased use of abdominal imaging, particularly abdominal computed tomography (CT). More often than not, these lesions are identified serendipitously, creating a conundrum for treating physicians: What should they do once these lesions have been identified? Because cancer of the pancreas is typically a fatal disease, the key to optimizing outcomes is early detection and appropriate management/intervention. These 2 reports from the recent literature focus on refining current strategies for the management of pancreatic lesions with a suspected neoplastic risk.

The first study is a retrospective analysis of a single gastroenterology center's experience with consecutive patients with pancreatic cystic lesions. Only asymptomatic patients were included, all of whom had incidental findings of a pancreatic cystic lesion identified by abdominal imaging. All patients underwent an index endoscopic ultrasound (EUS) exam. The specific morphology of each lesion was characterized by presence or absence of cyst wall or septation, solid component, and calcification. A serous cystadenoma was suspected if a microcystic pattern was identified. A mucinous neoplasm was suspected if there was a macrocystic pattern with an intracystic solid component. EUS-guided fine-needle aspiration (FNA) was performed when available, and the aspirates were sampled for cytopathology, amylase, and carcinoembryonic antigen levels. The decision to follow the patient or to refer for surgery was made by the referring physician in consultation with the patient. Lesions were considered to be malignant whenever cancer was present. The diagnosis of benign lesion was made with mucinous cyst adenoma, solid pseudopapillary tumor, serous cystadenoma, lymphangioma pseudocyst, or when other benign cystic conditions were identified. Patients who had pancreatic pseudocysts or were symptomatic were excluded from the analysis. A total of 112 patients were diagnosed as having true pancreatic cysts and followed; 14 were referred for surgery and 98 were managed conservatively by a nonsurgical approach of close follow-up. All of the patients sent to surgery had EUS characterization of macrocytic-appearing cysts: a solid component (5 patients) and distinct septations (6 patients), or a thickened wall (6 patients). Among those patients who were followed conservatively, there was clinical follow-up available for 63%. A search of the national death registry showed that the remaining patients were alive, with the exception of 2 patients in whom cause of death was not pancreas-related. In the 7-year follow-up, cystadenocarcinoma was established in only 1 of 57 patients. It is interesting to note that this patient had undergone several cyst aspirations before malignant transformation was evident.

The second report described the combined experience of 2 major pancreatic surgery centers; data on 145 patients with resected intraductal papillary mucinous neoplasms (IPMNs) were pooled. Although IPMNs have been recognized to have malignancy potential, recent consensus guidelines[1] have recommended nonsurgical management and close observation for IPMNs arising from branch ducts as opposed to the main pancreatic duct. Thus, this study from these 2 experienced, high-volume pancreatic surgery centers aimed to validate the recommendations for conservative management purported in the recent guidelines. The study authors evaluated the clinicopathologic characteristics and found that 11% of patients had carcinoma in situ, 11% had invasive carcinoma, 45% had adenoma, and 32% had "borderline tumors." The findings associated with the diagnosis of malignancy were: thick wall (P < .001), nodules (P < .001), and tumor ≥ 3 cm (P < .001). Over a mean follow-up of 45 months, the 5-year disease-specific survival for branch-duct IPMNs was 100% and for invasive cancer was 63%. Two thirds of the branch-duct IPMNs were located in the head or uncinate process of the pancreas.

The increased use of radiologic imaging of the abdomen has been helpful, yet in some circumstances has created new "problems." Pancreatic cystic lesions are identified more often given the expanded use of abdominal imaging. There has been considerable controversy regarding the management of these cystic lesions, and the literature to date has supported the need for surgical intervention. This approach has been justified given the concern for malignant transformation or of missing undetected foci of cancer at the time of the diagnosis. However, the first report suggests that the risk for malignant transformation is not likely if certain imaging criteria are met. Clearly, this is discrepant from previous literature, but it is likely that a tertiary referral center selection bias accounts for the prior data. As such, high-risk referrals would perhaps generate a different population perspective relative to more "real life" practice.

The second report shows that branch-duct IPMNs can also be managed conservatively, albeit with close follow-up. Lesions that are < 3 cm in diameter, have no nodules or thick wall, and are not associated with clinical symptoms/signs (eg, pain, pancreatitis, worsening diabetes, jaundice, weight loss) suggest an absence of malignancy. These lesions typically are located in the head of the pancreas and occur typically later in life (70s and 80s) and have a slight male predominance (1.5:1.0). These clinical parameters are different from mucinous cystic neoplasms (discussed in the first report), which typically are found in the periphery of the body or tail of the pancreas. These lesions also tend to occur earlier in life (50s) and have a marked female predominance (10-20:1).

Collectively, these reports provide important and reassuring evidence to support the growing consensus of more conservative management (with close follow-up) for pancreatic cystic lesions. The rationale for following this recommendation is justified by the lower reported malignancy, coupled with the recognizable morbidity and perhaps related mortality associated with more aggressive surgical intervention. These data will be particularly helpful in providing guidance for the management of elderly patients in whom these lesions are often discovered.

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