Radiopaque Hydrogel in Patients Undergoing Radiotherapy for Pancreatic Cancer

Pancreatic ductal adenocarcinoma is now the third leading cause of cancer-related death, with a devastating 5-year overall survival (OS) rate of nearly 8%, despite having the 12th most common incidence of all malignancies in the United States. One-third of patients will present with borderline resectable or unresectable, locally advanced pancreatic cancer (BR/LAPC). In the cases of LAPC, chemotherapy with or without radiation may be recommended to improve the quality of life by relieving symptoms and extending survival. Despite aggressive combined modality therapy, the median survival remains between 9 and 15 months.

Current guidelines for the management of BR/LAPC patients include single- or multi-agent chemotherapy or chemoradiation (CRT) in sequence with chemotherapy. Results of studies comparing chemotherapy alone to CRT for patients with BR/LAPC are mixed. The importance of local control or delaying local progression on improving morbidity and possibly mortality in patients with pancreatic cancer is supported by autopsy data demonstrating that 30% of patients die of locally destructive disease. It follows that in the cases of LAPC, advanced radiation therapy techniques using dose-escalation with intensity modulated radiotherapy (IMRT) and stereotactic body radiotherapy (SBRT) are potential strategies to improve local control.

A consistent challenge to dose-escalation with IMRT (intensity modulation radiation therapy) or SBRT is the sensitivity of the surrounding gastrointestinal organs, particularly the small bowel which is directly adjacent to the head of the pancreas head of the pancreas (HOP). For BR/LAPC patients treated with CRT, advances in image guidance have provided the opportunity to safely deliver higher biologically effective doses of radiation therapy using IMRT of >70 Gy (57.25 Gy in 25 fractions, BED 70.36 Gy) compared to standard fractionation regimens (50.40 Gy in 28 fractions or 50 Gy in 25 fractions, BED 59.47 Gy and 60 Gy, respectively). Those patients who underwent dose-escalated CRT with BED>70 Gy, did have a superior OS compared to those receiving BED<70 Gy, supporting the utility of dose-escalation in improving long-term outcomes. SBRT involves a short course of radiation therapy, five fractions or less, and has demonstrated higher rates of local control compared to CRT in other disease sites. Early studies evaluating SBRT for pancreatic cancer utilized single fractions of 25 Gy, resulting in local control rates of 100% at 1 year but unacceptably high rates of gastrointestinal toxicity. More recently, hypofractionated SBRT (33 Gy total, 6.6 Gy daily fractions) has been evaluated and utilized by our group in an effort to reduce the toxicity of therapy, with results demonstrating nearly 80% rate of freedom from local progression at one year and an acceptable 11% long-term gastrointestinal toxicity. Outcomes with SBRT are thus promising; however, higher local control rates with dose-escalation may be achievable, but current practice is limited due to risks of toxicity.

The goal of this pilot imaging study is to evaluate the visibility of marking the interface between the pancreas and duodenum with TraceIT Tissue Marker. Patients with a pathologically confirmed diagnosis of BR/LAPC pancreatic adenocarcinomas indicated for neo-adjuvant image-guided radiotherapy with SBRT will be enrolled. This study will thus set the stage for further investigations using the TraceIT Tissue Marker to avoid duodenum toxicity with imaging localization, enabling further dose intensification with SBRT or IMRT to improve the clinical outcomes in BR/LAPC.