ENDOSCOPIC ULTRASOUND-GUIDED HYBRIDTHERM ABLATION (EUS-HTP) IN PATIENTS (PTS) WITH LOCALLY ADVANCED (LA) PANCREATIC DUCTAL ADENOCARCINOMA (PDAC): A CASE-CONTROL COMPARATIVE SURVIVAL ANALYSIS

Background & Aim: A preliminary report involving 16 pts with LA PDAC showed that EUS-HTP was feasible and safe, with a 6-month post treatment survival. Aim of the study was to assess the outcomes of LA PDAC pts treated with chemothera py radiotherapy (CT RT) plus EUS-HTP vs those receiving only CT RT. Material & Methods: The study population is constituted by pts with LA PDAC, with local dis ease progression (PD) after 1st line CT RT or unfit for CT; cases prospectively treated by HTP (2010–2016) were retrospectively compared to similar pts not treated by HTP (controls) but candidate to 2nd line CT RT. HTP (ERBE, Germany), a bipolar probe combining radiofrequency with cryogenic cooling, was used under EUS guidance. Overall survival (OS) was assessed by clinical follow-up. Data were analyzed with parametric/non-parametric tests for group differences and Log-rank Mantel-Cox tests for survival curves (P 0.05 as statistically significant). Results: 19 cases and 19 controls were included with a complete survival follow-up. Five cases did not receive 1st line CT RT before HTP due to concomitant comorbidity. The 2 groups had no significant difference regarding features at diagnosis (sex, age, lesion site and size, serum CA19.9, administered CT scheme and duration) and after 1st line treatment (lesion size, serum Ca 19-9, progression-free survival time). HTP was performed 2 times in 7 cases. Median OS (months) in cases vs controls from initial diagnosis, start of 1st line CT RT and local PD was similar (18 vs 18, pZ0.22; 17 vs 17.5, pZ0.82; 7 vs 4, pZ0.54). Excluding pts not previously treated with CT RT, median OS (months) in cases vs controls from diagnosis, start of 1st line CT RT and local PD was similar in pts treated with further CT RT regimens (19 vs 20, pZ0.12; 17.5 vs 19.5, pZ0.68; 8 vs 5, pZ0.94). Median OS (months) was significantly longer from local PD in cases compared to controls who did not undergo 2nd line CT RT (6 vs 3, pZ0.05); it was similar from diagnosis and start of 1st line CT RT (pZ0.15; pZ0.17). As far as the 19 cases treated with HTP, median OS from treatment was 6 months, with no difference between pts treated with HTP only and those receiving concomitant CT RT (4.5 vs 8.5, pZ0.18). Median OS (months) from HTP was significantly longer in pts treated with 2 HTP sessions vs 1 session (9 vs 4.5, pZ0.007). Conclusions: In pts with LA PDAC and local PD after 1st line CT RT, OS of pts treated with HTP plus CT RT was similar to that seen in pts treated with CT RT alone. In pts who were unfit for a 2nd line treatment, however, HTP may obtain longer OS compared to palliative care only. The increase of OS in pts treated by 2 HTP sessions may suggest that repeated sessions can achieve a better disease control. A randomized controlled study comparing HTP plus CT RT vs CT RT alone is ongoing and will better assess the efficacy of EUS-HTP.