EUS AND CT SCAN ACCURACY IN ESTABLISHING THE T STAGE IN SURGICALLY RESECTED PANCREATIC CANCER BASED ON THE UPCOMING TNM 8TH EDITION

Aims:

Pancreatic cancer (PC) patients with tumors > 2 cm might harbor micrometastases already at diagnosis. In fact, the new proposed AJCC-Staging-System-TNM-8^th edition differs from the 7^th mostly for T evaluation, giving high importance to PC diameter, predicting survival more efficiently. A correct preoperative evaluation of the T might shift therapeutic decision from upfront surgery to neoadjuvant chemotherapy, that could be preferred in tumors> 2 cm (T2). Few studies compared CT vs. EUS in evaluating PC dimension with heterogeneous results and dated machines, and no study adopted the new TNM system. The aim was to evaluate the accuracy of CT vs. EUS in establishing the T stage as defined by the new upcoming TNM 8^th edition and to discriminate T1 from more advanced stages.

Methods:

Retrospective/prospective unicenter-cohort of surgically-resected PC patients, having preoperative EUS+CT performed at our center. T evaluation by both imaging modalities was compared to the pathology T re-established based on the new TNM 8^th edition, calculating specificity, sensitivity and PPV in discriminating T1 from ≥T2 lesions.

Results:

40 patients included, 57.6% males, mean age 68.7 years. In 5 (12.5%) cases CT wasn't able to detect the lesion. PPV was 75% for CT, 84.2% for EUS; when considering detection of≥T2 lesion in any of the two imaging modalities this increased to 86.9%. Sensitivity and specificity was respectively 64.0% and 80.0% for EUS and 66.7% and 60.0% for CT.

Conclusions:

This is the first study evaluating CT vs. EUS imaging modalities in T evaluation in the setting of the new TNM 8^th edition. In our study, EUS has a higher PPV in discriminating T1 from≥T2 lesions compared to CT, which increases even more when used in combination with CT. CT was not able to detect up to 12.5% lesions. EUS resulted having a lower sensitivity but higher specificity. Therefore EUS, often adopted only to obtain a cytological specimen, has a key role in determining the T stage, and that the two imaging modalities should be used in combination to better assess the proper therapeutic management as for neoadjuvant chemotherapy or upfront surgical resection.