A Single-center Prospective Observational Study Investigating the Accuracy of Preoperative Diagnostic Procedures in the Assessment of Lymph Node Metastases in Nonfunctioning Pancreatic Neuroendocrine Tumors

Abstract

To determine the accuracy of preoperative imaging, including contrast-enhanced computed tomography (CE-CT), endoscopic ultrasound (EUS), and 68 Gallium-DOTATOC positron emission tomography ( 68 Ga-DOTATOC PET), in identifying nodal metastases (N+) in sporadic nonfunctioning pancreatic neuroendocrine tumors (NF-PanNETs). Background: An accurate preoperative identification of N+ in NF-PanNETs is critical for surgical planning. The accuracy of different imaging techniques in detecting lymph node (LN) metastases in NF-PanNETs has been poorly investigated. Methods: All consecutive patients undergoing surgery for sporadic NF-PanNETs (2018 were enrolled in a prospective study (DETECTYON; NCT03918759). The accuracy of preoperative imaging techniques in detecting N+ was assessed through sensitivity, specificity positive and negative predictive values. Results: Overall, 100 patients with NF-PanNETs underwent CE-CT, EUS, and 68 Ga-DOTATOC PET before pancreatic resection. LN metastases were found in 42 cases (42%). Sensitivity, specificity, positive predictive value, and negative predictive value of different imaging techniques were 26%, 95%, 79%, 64% for CE-CT, 19%, 98%, 89%, 63% for EUS, and 12%, 95%, 63%, 60% for 68 Ga-DOTATOC PET, respectively. Radiologic tumor size > 4 cm and the presence of radiologic N+ at ≥ 1 imaging were independent predictors of N+ at pathology. The identification of N+ at ≥ 1 imaging technique was associated with a higher number of positive LNs compared with negative imaging (4 vs 2) (P = 0.012). Conclusions: CE-CT, EUS, and 68 Ga-DOTATOC PET are poorly sensitive in predicting nodal status in NF-PanNETs despite a high specificity.

Clinicoradiological Factors Predicting Lymph Node Metastasis in Patients with Nonfunctioning Pancreatic Neuroendocrine Neoplasms: A Systematic Review and Meta-Analysis

“…All studies used cohorts of patients with nonfunctioning pNENs who underwent surgical resection and enrolled the patients retrospectively. Five studies used an eastern (Asia/Pacific) population [11–13, 15, 20] and four used a western (Europe or North America) population [10, 14, 16, 18]. Moreover, two studies used combined eastern and western population [17, 19].…”

“…Moreover, two studies used combined eastern and western population [17, 19]. Five studies were single-center studies [11–13, 15, 18], while the remaining were multi-institutional studies obtained from two to nine different institutions [10, 14, 16, 17, 19, 20]. The proportion of patients with lymph node metastasis ranged from 6.4% to 58.0%.…”

Recurring Pancreatic Neuroendocrine Tumor: Timing and Pattern of Recurrence and Current Treatment

“…However, while a radical pancreatic resection with R0 margins is advocated for PanNETs, it is unclear whether an extended lymphadenectomy would prevent the development of a distant recurrence, and perhaps improve OS. To date, no randomized controlled trial has been conducted to investigate this topic, but retrospective data suggests that extended lymphadenectomy does not offer any advantages in terms of staging and treatment as nodal metastases outside the standard lymphadenectomy area are rare (1%) 15 . The North American Neuroendocrine Tumor Society guidelines recommend harvesting 11 to 15 lymph nodes during formal resections and performing nodal sampling during parenchyma sparing procedure, for staging purposes 16 .…”

“…To date, no randomized controlled trial has been conducted to investigate this topic, but retrospective data suggests that extended lymphadenectomy does not offer any advantages in terms of staging and treatment as nodal metastases outside the standard lymphadenectomy area are rare (1%). 15 The North American Neuroendocrine Tumor Society guidelines recommend harvesting 11 to 15 lymph nodes during formal resections and performing nodal sampling during parenchyma sparing procedure, for staging purposes. 16 Indeed, it should be noted that given the current lack of indications for adjuvant treatments, the retrieval of metastatic lymph nodes will likely only help define the risk of recurrence without any possibility of intervention to reduce such risk.…”

European Neuroendocrine Tumour Society (ENETS) 2023 guidance paper for nonfunctioning pancreatic neuroendocrine tumours

“…The main drawback of atypical resections is the lack of an adequate lymphadenectomy, and, for this reason, they should be avoided in patients with Pan‐NET at risk for nodal metastases. Unfortunately, there are no preoperative examinations able to accurately predict the presence of nodal involvement in NF‐Pan‐NET 40 . Consequently, lymphadenectomy should be routinely performed for NF‐Pan‐NET >3 cm.…”