Visceral Artery Pseudoaneurysm Rates after Pancreatoduodenectomy in Patients Who Received Pre-Operative Radiation for Pancreatic Cancer

Abstract

The role of pre-operative radiation therapy (RT) for localized pancreatic ductal adenocarcinoma (PDAC) with peri-pancreatic vascular involvement remains controversial, with two recent randomized controlled trials, namely PREOPANC-1 and Alliance A021501, showing conflicting results. Opponents of pre-operative radiation point towards the unclear oncologic benefit and potential added toxicity. While hemorrhage from a pseudoaneurysm (PsA) rupture is a known rare but potentially fatal complication after pancreaticoduodenectomy (PD), with published incidence rates of around 2 to 5%, it has been increasingly common in the pancreatic cancer surgical community for pre-operative RT to be cited as a risk factor for PsA development, despite the absence of data supporting this notion. Certainly, accurate characterization of relevant RT-related toxicities is critical to prevent inaccurate decision-making regarding foregoing its use. As such, we aim to report on the incidence of PsA in a cohort of patients with PDAC who underwent pre-operative RT prior to PD at a high-volume center. Consecutive patients treated with pre-operative RT via stereotactic body radiation therapy (SBRT) or intensity modulated radiation therapy (IMRT) prior to PD for borderline resectable or locally advanced PDAC were retrospectively reviewed. Incidence of radiographic or clinically apparent PsA was reported. We also characterized the timing of PsA identification in relation to surgery and RT, the artery in which the PsA developed, and the clinical outcomes of patients after PsA identification. One hundred seventy-five patients met eligibility criteria for our analysis. Most of our cohort (163 patients, 93%) received SBRT to a median dose of 6.6 Gy x 5 (median BED10 54.78 Gy, range: 48 Gy - 61.92 Gy), and only 12 patients (7%) received IMRT in various fractionation and dose patterns (median BED10 62.94 Gy, range 59.47 Gy - 97.5 Gy). The median time between surgery and last contrast-enhanced abdominal imaging was 17 months (range: 0.23 - 68 months). There were fourteen visceral arteries among thirteen patients (7%) that were found to have a PsA on routine follow-up imaging or after a post-PD hemorrhage. The median time between completion of radiation and surgery to PsA were 19.5 weeks (range: 8.6 to 98.1 weeks) and 13 weeks (range: 1.6 to 87.9 weeks), respectively. The two most commonly involved arteries were the gastroduodenal and superior mesenteric arteries. Rate of PsA development was similar among patients treated with SBRT (7%) and IMRT (8%). In terms of Clavien-Dindo classification of complications, there were six patients with grade 3a complications, five patients with grade 4b complications, and two patients with grade 5 complications. Compared to historical data, pre-operative RT does not appear to significantly increase the risk of PsA development after PD. More data on the impact of pre-operative radiation dose-fraction regimen and longer follow-up are needed.