High rates of morbidity and mortality are a widespread outcome in patients with metastatic pancreatic cancer exhibiting local progression. Dr. Russell Palm, a radiation oncologist at Moffitt Cancer Center, presented research findings at ASTRO on the administering of MRI-guided adaptive radiation therapy (MRgART) with ablative dose, possibly offering local disease control and improving clinical outcomes for specific metastatic patients with chemotherapy-responsive disease.
The study included performing a multi-institutional retrospective analysis of de novo metastatic pancreatic cancer patients who received high biological effective dose MRgART to their primary disease on a 0.35T MR-Linac in 5 fractions. Local and distant disease recurrence was evaluated by Response Evaluation Criteria in Solid Tumors (RECIST 1.1) or by radiographic evidence of progression with initiation or change in systemic therapy. Toxicity was measured by Common Terminology Criteria for Adverse Events (v5) at routine follow-up appointments. Primary clinical outcomes of interest were overall survival (OS) censored at last clinical follow-up and freedom from local failure (FFLF) censored at last dedicated abdominal imaging.
The cohorts ranged of 22 metastatic patients with a median age of 66 years and a slight male predominance (59%) were treated with induction FOLFIRINOX (64%, median 13 cycles, 224 days) or Gemcitabine/nab-Paclitaxel (36%, median 7 cycles, 220 days) followed by ablative dose MRgART to a median dose of 50 Gy (range 40-50). Last follow up outcomes presented 19 patients (86%) had experienced distant progression and 13 (69%) had died. One patient underwent a margin negative distal pancreatectomy and metastasectomy of a treated retroperitoneal tumor implant and is without recurrence at 16 months post-diagnosis. Two patients experienced grade 3+ toxicity, one patient with duodenal involvement at diagnosis and on anti-coagulation during treatment experienced a gastrointestinal bleed at 69 days post-MRgART and portal vein pseudoaneurysm 168 days post-MRgART. The second patient developed gastric outlet obstruction 430 days post-MRgART. There was no grade 5 toxicity.
Overall results concluded that some metastatic pancreatic cancer patients with stable or chemotherapy-responsive disease appear to benefit from aggressive local therapy possibly mitigating morbidity of primary tumor progression. Further investigation into the optimal patient selection for this treatment is warranted.
Read Dr. Palm’s complete ASTRO abstract.
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