3380 - CoVART: A Retrospective Cohort Study of Conventionally Fractionated RT vs. Ablative RT Dosing in the Treatment of Locally Advanced Pancreatic Cancer

Purpose/Objective(s): Ablative chemoradiotherapy is an emerging approach to the treatment of locally advanced pancreatic cancer (LAPC). We performed a retrospective analysis of patients with unresectable LAPC to compare overall survival (OS), and distant progression free survival (DPFS) between patients who received ablative chemoradiotherapy (ART) as opposed to standard chemoradiotherapy (CRT).

Materials/Methods: A single-institution retrospective analysis was performed using data from patients diagnosed with LAPC who did not undergo surgical resection of their pancreatic primary lesion and received radiotherapy (RT) from 2015-2023. The ART prescription regimens were 75 Gy/25# and 67.5 Gy/15# (alpha/beta=10, BED=98 Gy). The OS, and DPFS between ART and CRT were estimated and compared using Kaplan Meier curves and the log-rank test.

Results: Of the 76 eligible patients, the mean age was 69 years, 37 (49%) were female, and 27 (35%) received ART. The ART cohort was treated between 2020-2023, while the CRT cohort was treated across the entire study period. The most common chemotherapy regimens prior to RT were FOLFIRINOX (36%) and gemcitabine/nab-paclitaxel (25%). Capecitabine and continuous infusion 5-Fluorouracil were the most common radiosensitizers (57%). Median OS for ART was 18.2 months vs 13.8 months for CRT (p=0.18). The study included 8 patients who were metastatic at diagnosis, 2 in the ART arm, and 6 in the CRT arm. Of the patients who developed distant metastasis after treatment (n= 42, 55.3%), median DPFS for ART was 11.2 months compared to 7.5 months for CRT (p=0.25).

Conclusion: ART is a technique to deliver higher BEDs to pancreatic tumors that provides optimistic results for improvement in distant progression free and overall survival in patients with unresectable, LAPC when compared to the current standard.