Ex‐vivo investigation of radiofrequency ablation in pancreatic adenocarcinoma after neoadjuvant chemotherapy

Abstract

Objective Endoscopic ultrasound (US)‐guided radiofrequency ablation (RFA) has been investigated for pancreatic ductal adenocarcinoma (PDAC) but studies are limited and heterogeneous. Computed tomography (CT) scan features may predict RFA response after chemotherapy but their role is unexplored. The primary aim was to investigate the efficacy of ex‐vivo application of a dedicated RFA system at three power on surgically resected PDAC in patients who underwent neoadjuvant chemotherapy. The secondary aim was to explore the association between pre‐treatment CT‐based quantitative features and RFA response. Methods Fifteen ex‐vivo PDAC samples were treated by RFA under US control at three power groups (10, 30, and 50 W). Short axis necrosis diameter was measured by two expert blinded pathologists as the primary outcome. Two radiologists independently reviewed preoperative CT images. Results Eighty percent of specimens showed coagulative necrosis consisting of few millimeters: 5.7 ± 3.9 mm at 10 W, 3.7 ± 2.2 mm at 30 W, and 3.5 ± 2.4 mm at 50 W ( p = 0.3), without a significant correlation between power setting and mean necrosis short axis (rho = –0.28; p = 0.30). Good agreement was seen between pathologists ( k = 0.76; 95% confidence interval 0.55–0.98). Logistic regression analysis did not show associations between CT features and RFA response. Conclusions RFA causes histologically evident damage with coagulative necrosis of a few millimeters in 80% of ex‐vivo PDAC samples after chemotherapy and no clinical or pre‐operative CT features can predict efficacy. Power settings do not correlate with the histological ablation area. These results are of relevance when employing RFA in vivo and planning clinical trials on its role in PDAC patients.

Approaching Small Neuroendocrine Tumors with Radiofrequency Ablation

“…The coagulative necrosis obtained with RFA (confirmed by a specialist pancreatic pathologist) did not differ among the ablation settings (mean size 3.25 mm). After this experience, other tests were performed on human surgical samples of pancreatic adenocarcinoma (PDAC), treating three groups of samples ex vivo (probe 19 G with 1 cm active part) at 10, 30, and 50 W [55]. Eighty percent of the specimens showed coagulative necrosis at histology consisting of a few millimeters (the majority had a size of 5.7 ± 3.9 mm at 10 W; those not statistically significant with respect to necrosis were obtained at 30 and 50 W).…”

“…Further studies may also assess whether radiological studies are able to accurately compare the necrotic area obtained with RFA to the surrounding healthy tissue. No such comparison is evident in the aforementioned studies, though the Italian group (previously cited [55]) tried to analyze the coagulative necrosis obtained inside PDAC samples through contrast-enhanced CT scan parameters. Qualitative and quantitative parameters were extracted to establish the RFA response and lesion fibrosis content.…”