EUS vs CT for pancreatic cancer

The November 16 Annals has an article from Indiana University comparing endoscopic ultrasound with multidetector CT scanning for the evaluation of suspected pancreatic cancer.

104 patients with suspected non-metastatic pancreatic malignancy underwent both EUS and high-resolution multidetector CT scanning. Of these patients, 41 were managed medically, and 63 underwent surgery. The two modalities were then compared for their accuracy in determining resectability, staging and detection of tumors.

The original hypothesis was that EUS would be better at determining resectability (in particular recognizing unresectable tumors) than CT scanning, and resectability was the study’s primary endpoint. There was no significant difference between the two modalities for this endpoint: resectable tumors were correctly identified by EUS vs CT in 88% vs. 92%. Non-resectable tumors were accurately identified by EUS vs CT in 68% vs 64%. The authors conclude that “if multidetector CT detects a pancreatic mass that seems to be resectable in an appropriate surgical candidate with suspected cancer, preoperative endoscopic ultrasonography does not seem to be necessary unless tissue confirmation of suspected malignancy is desired”.

Secondary endpoints were staging and the actual detection of tumors. In terms of overall staging, endoscopic US was superior to CT scanning, due to better recognition of T3 disease. For nodal staging, there was no significant difference.

Interestingly, EUS was superior to CT scanning in the detection of small tumors. Among the 63 patients who underwent surgery, 53 were found to have cancer. Of these 53, endoscopic ultrasound failed to diagnose 2 tumors less than 25 mm in size; CT scanning missed 10 tumors, 9 of which were less than 25 mm and one greater than 25 mm. Most of these were in the head of the pancreas. The authors do not specifically explain how 10 patients who had no pancreatic masses on CT scanning came to be evaluated for suspected pancreatic cancer, but 4 of them had had biliary stents placed, so presumably biliary obstruction was the presenting symptom for many of these CT-negative cases.

Thus, endoscopic ultrasound was not superior to CT scanning in determining resectability of pancreatic tumors but was superior in picking up small (less than 25 mm) masses that turned out to be cancers at surgery. This study, supported by grants from the American Society of Gastrointestinal Endoscopy, does not make endoscopic ultrasound an obligatory part of the resectability work-up, which was presumably the original intent. It certainly does raise the question of the role of EUS in the work-up of patients with possible pancreatic neoplasms, however, since it was able to pick up small tumors that escaped CT detection.