Canadian vs American Pancreatic Cystic Lesions Guidelines Safe, More Cost-Effective

A study published in the Journal of the Canadian Association of Gastroenterology found that the Canadian Association of Radiologists surveillance guidelines (CARGs) about pancreatic cystic lesion (PCL) surveillance were safe and more cost-effective than the American Gastroenterology Association guidelines (AGAGs) or the American College of Radiology guidelines (ACRGs).

Rates of incidental PCLs have been increasing, with the prevalence estimated between 2% and 45%. The presence of PCLs is associated with a 19.64-times higher risk for developing pancreatic malignancy. As such, monitoring for PCLs is important for early cancer detection, and multiple expert societies have published surveillance guidelines that balance patient health with monitoring costs.

However, as little is known about the natural history of PCLs, these guidelines are primarily based on expert opinion and considerable deviations exist between guidelines.

The CARG recommends for patients with enhancing mural nodules 10 mm in size or greater in the main pancreatic duct or with obstructive jaundice with cystic lesions in the pancreatic head to undergo magnetic resonance imaging (MRI) surveillance at 1 year, repeated every 2 years up to 5 years if the cyst is unchanged or 10 years for patients aged 40 to 49 years. A gastroenterology (GI) consultation is recommended for patients who have a cyst that develops concerning features or grows at least 3 mm. Other indications for a GI consultation include age younger than 40 years, cyst 2.5 cm or greater, cyst focal wall thickening, nonenhancing mural nodules, regional lymph node enlargement, and/or abrupt changes to the pancreatic duct diameter with upstream atrophy. Surveillance is not recommended for patients who are aged over 75 years or with a simple cystic lesion 5 mm in size.

The AGAG recommendations are for patients with a solid component cyst and dilated pancreatic duct and/or concerning features observed during endoscopic ultrasound (EUS) and fine needle aspiration (FNA) to undergo surveillance by MRI at 1 year followed by every 2 years up to 5 years if the cyst is unchanged. If cystic changes are observed, a GI consultation is suggested. Other indications for a GI consultation include cysts with 2 or more high-risk features of 3 cm or greater in size, presence of a solid component, and dilated main pancreatic duct. Surveillance should be discontinued if the patient is no longer a candidate for surgery.

The ACRG recommends surveillance for patients with a cyst 2.5 cm or larger with interval growth or accompanied by obstructive jaundice, enhancing solid component, or dilated main pancreatic duct 10 mm or larger. Surveillance comprises regular follow-up for 9 or 10 years, every 6 months or 2 years, depending on cyst features. A GI consultation is recommended when cystic changes are observed or when the cyst is 2.5 cm or larger. Patients with a cyst 1.5-2.5 cm in size may undergo EUS/FNA instead of MRI.

To evaluate whether one of these guidelines is superior to the others with regard to cost-effectiveness, investigators from University of Alberta in Canada performed this multicenter, retrospective study. Patients (N=1001) who were diagnosed with PCL by MRI between 2018 and 2019 in a single health zone in Canada that serves a population of over 1.3 million individuals were evaluated for outcomes and costs using predictive models based on the CARGs, AGAGs, and ACRGs.

The study population comprised patients with a mean [SD] age of 64.4 [12.01] years, their average cyst size was 1.24[1.105] cm, 53.41% had 1 cyst, and 4.19% had high-risk features and 3.50% concerning features at MRI.

Follow-up was recommended for 54.3% of the patients according to the CARG and 23.9% according to the AGAG/ACRG.

Patients who were recommended for follow-up by the CARG were older (mean, 65.9 vs 62.4 years; P <.001), they had smaller cyst sizes (mean, 1.1 vs 1.6 cm; P <.001), and fewer had high-risk features (3.1% vs 6.2%; P =.042), an enhancing solid component (1.8% vs 5.4%; P =.006), or a non-enhancing solid component (0% vs 0.8%; P =.033) compared with the AGAG/ACRG follow-up cohort, respectively.

During follow-up fewer patients followed by CARG had interval cyst growth (1.1% vs 20.3%; P <.001), and fewer were referred for GI (9.4% vs 17.0%; P =.002) or surgical (9.4% vs 17.0%; P =.016) consultation compared with AGAG/ACRG, respectively.

In the 10-year model of each guideline, the CARGs were predicted to result in 1304 MRIs, 119 GI consultations, and 35 pancreatic surgeries; AGAGs in 5850 MRIs, 48 GI consultations, and 4 surgeries; and ACRGs in 5776 MRIs, 82 GI consultations, and 76 surgeries.

The total costs of these interventions were lowest for the CARGs (CAD$516,183), followed by AGAG (CAD$1,908,425) and ACRG (CAD$1,924,607). Stratified by components of cost, the lowest costs for MRI were associated with CARG (CAD$1304), GI consultation with AGAG (CAD$37,440), and surgery with AGAG (CAD$740).

As data were collected in Canada, adherence to CARG was evaluated. Among patients recommended for surveillance, 54.3% had appropriate follow-up. These rates suggested substantial inter-site variability in guideline adherence. Among the 45.7% who received non-CARG-recommended follow-up, 36.6% were underscreened and 63.4% overscreened. For example, the CARG recommends for surveillance to stop at 75 years of age, however, 47 patients aged over 75 years underwent MRI.

Following the CARGs were associated with a favorable safety profile, in which among the 253 patients recommended for surveillance discontinuation, 1.6% (n=4) developed pancreatic adenocarcinoma.

This study was limited by not including PCL surveillance guidelines from societies outside North America.

Study authors concluded, “The CARGs represents a Canadian specific guideline for PCL surveillance that, compared to other North American guidelines, offer substantial cost savings and potentially improved MRI access. Current follow-up data supports safety of current CARG recommendations to discontinue surveillance for patients >75 years old and with PCL <0.5 cm, and also suggests ease of CARG uptake, however, future studies evaluating long-term safety are needed.”