58 y/o F with borderline resectable pancreatic adenocarcinoma cT4N0M0, s/p neoadjuvant FOLFIRINOX x4C with local progression, gem/nab-paclitaxel x3C, now on single-agent gem. Referred for consideration of pre-operative radiotherapy.
Technique: She was treated with SBRT 40 Gy in 5 fractions daily.
Dose: 40 Gy to the tumor, 25 Gy to elective nodal regions, performed as simultaneous integrated boost.
Simulation:
Contours per RTOG-0848 atlas and 2012 RTOG Consensus Guidelines.
GTV: Visible tumor on CT/PET/MR.
CTV: None
ITV: Use 4DCT. We prefer expiratory gating with fiducials (breath hold if does not have/cannot get fiducials).
PTV40: ITV + 3mm (given immobilization, fiducials, and CBCT daily).
CTV25: Elective nodal regions (peripancreatic, celiac, superior mesenteric artery, porta hepatic, para-aortic nodes).
PTV25: CTV25 + 5mm (no ITV, and slightly bigger PTV since IGRT is aligned to tumor)
Optional: PTV50 simultaneous integrated boost to tumor/vascular interface (if can still safely meet duodenum/bowel constraints).
OARs: Duodenum given proximity (granted irradiated duodenum will be removed if patient goes to surgery, but can be hard to predict so we prioritize duodenal constraints over tumor coverage).
Higher BED improves local control:
Pros of SBRT:
Elective nodal irradiation (ENI) is controversial:
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