In patients with pancreatobiliary cancer, para-aortic lymph node (PALN) metastasis is considered to be the involvement beyond the regional lymph nodes, namely, distant metastasis. Effective methods for preoperative PALN staging, however, are not established. This study aimed to compare the diagnostic capability for PALN metastasis between EUS-FNA and ¹⁸F-fluorodeoxyglucose positron emission tomography with CT (PET/CT).

We performed a prospective, nonrandomized, single-center trial. Between December 2010 and March 2014, 208 patients with pancreatobiliary cancer without apparent distant metastasis except for PALNs were assessed for study eligibility before surgery. Among them, 52 consecutive patients with PALN enlargement were enrolled in the study. ¹⁸F-Fluorodeoxyglucose PET/CT and EUS-FNA were performed sequentially as a single combined procedure to evaluate PALN metastases. The primary outcome was to compare the diagnostic capability of EUS-FNA and PET/CT for PALN metastasis.

Of 71 enlarged PALNs in the 52 patients, 30 (42.3%) were finally diagnosed as metastases in 21 patients (40.4%). Of the 21 patients with PALN metastases, preoperative EUS-FNA or PET/CT made a correct diagnosis in 20 (95.2%) or 12 (57.1%), respectively. EUS-FNA had higher sensitivity and specificity for the diagnosis of PALN metastasis (sensitivity, 96.7% [29/30]; 95% confidence interval, 82.2%-99.9%; specificity, 100% [39/39]; 95% confidence interval, 91.0%-100%) than PET/CT.

EUS-FNA is superior to PET/CT for preoperative PALN staging in patients with pancreatobiliary cancer. Because of the clinical benefit of EUS-FNA to reduce unnecessary surgery, it should be part of the standard preoperative examination for patients with pancreatobiliary cancer. (UMIN clinical trials registry number: 000006408.)