Main Session
Sep
27
PQA 01 - Gastrointestinal Cancer and Central Nervous System
2177 - Are Late Complications Emerging in Patients Treated with Stereotactic MR-Guided Adaptive Radiation Therapy (SMART) for Pancreatic Cancer?
Presenter(s)
Sarah Pilarski, BS - Michigan State University College of Human Medicine, East Lansing, MI
S. Pilarski1, E. Nguyen2, M. Gilbert3, J. Dragovic4, and P. J. Parikh3; 1Michigan State University College of Human Medicine, East Lansing, MI, 2Henry Ford Health System, Detroit, MI, 3Department of Radiation Oncology, Henry Ford Health, Detroit, MI, 4Henry Ford Cancer Institute, Detroit, MI
Purpose/Objective(s):
Stereotactic MR-guided adaptive radiation therapy (SMART) has been shown in prospective and retrospective studies to result in limited acute toxicity and promising long-term tumor control in pancreatic adenocarcinoma. However, similar conclusions were drawn with historical hypofractionated regimens of 25 Gy x 1 fraction before cumulative late toxicity rates of up to 28% were observed in long-term survivors without progressive disease (Chang, 2009). This study evaluates late gastrointestinal (GI) toxicity in patients with pancreatic adenocarcinoma treated with SMART who survived at least 12 months following radiation initiation. Hypothesis: Among pancreatic adenocarcinoma patients who survive =12 months after SMART without surgical resection, clinically significant late gastrointestinal bleeding occurs infrequently and is predominantly observed with anticoagulation, cirrhosis, or disease progression.Materials/Methods:
A retrospective review was conducted of 241 patients with pancreatic cancer treated with SMART at a single institution between 2018 and 2024. Patients surviving =12 months from radiation initiation without surgical resection were included to reduce mortality risk and allow for assessment of late toxicity. Demographic, tumor, treatment, and systemic therapy data were collected. The primary endpoint was CTCAE grade =3 GI bleeding occurring =6 months after radiation. Outcomes were summarized descriptively, with exploratory evaluation of anticoagulation use, comorbid conditions, and local disease status.Results:
Among the 241 treated patients, 101 patients survived =12 months from radiation initiation (17/56 medically inoperable, 39/63 borderline resectable, 28/37 locally advanced, 6/13 recurrent/salvage). Sixty-one of these patients did not have surgery and met inclusion criteria for this study with median follow-up from radiation of 19 months (range 3-79). Thirteen patients (21%) developed GI bleeds at a median of 13 months (range 4-31) after radiation, either requiring transfusion and/or endoscopic therapy. Among these, 11 patients had a single bleed, one patient had two bleeds within one month, and one patient had seven recurrent bleeds over three years, related to a pancreaticoduodenal artery pseudoaneurysm and managed endoscopically. No patient required surgical intervention. Only five patients (8.6%) developed GI bleeds in the absence of anticoagulation, cirrhosis, or disease progression.Conclusion:
Among long-term survivors treated with SMART, clinically significant late GI bleeding was uncommon in the absence of competing risk factors. No patient required operative management. SMART was associated with a low rate of late toxicities, even when limiting analysis to long-term survivors.