Stereotactic MR-Guided On-Table Adaptive Radiation Therapy (SMART) for Patients with Borderline or Locally Advanced Pancreatic Cancer: Primary Endpoint Outcomes of a Prospective Phase II Multi-Center International Trial
Recommended Citation
Parikh PJ, Lee P, Low D, Kim JP, Mittauer KE, Bassetti MF, Glide-Hurst C, Raldow A, Yang Y, Portelance L, Zaki B, Kim H, Mancias JD, Ng J, Pfeffer RM, Mueller A, Kelly P, Boldrini L, Fuss M, Chuong MD. Stereotactic MR-Guided On-Table Adaptive Radiation Therapy (SMART) for Patients with Borderline or Locally Advanced Pancreatic Cancer: Primary Endpoint Outcomes of a Prospective Phase II Multi-Center International Trial. Int J Radiat Oncol Biol Phys 2022; 114(5):1062-1063.
Document Type
Conference Proceeding
Publication Date
12-1-2022
Publication Title
Int J Radiat Oncol Biol Phys
Abstract
Purpose/Objective(s): Retrospective studies demonstrate that ablative stereotactic MR-guided on-table adaptive radiation therapy (SMART) achieves favorable local control (LC) and overall survival (OS) with limited grade 3+ toxicity compared to historical non-ablative outcomes for locally advanced and borderline resectable pancreatic cancer (LAPC/BRPC). We conducted an international multi-center single-arm phase 2 trial of ablative 5-fraction SMART for LAPC/BRPC. Materials/Methods: Subjectswere required to have biopsy-confirmed adenocarcinoma, receive ≥3 months of chemotherapy, have no distant metastasis and CA19-9 ≤500 U/mL. SMART was delivered on a 0.35T MR-60Co or MR-linac system prescribed to 50 Gy in 5 fractions (biologically effective dose10 [BED10]=100 Gy) using continuous intrafraction cine-MRI, soft tissue tracking, and automatic beam gating. The original plan was recomputed onto the daily anatomy and if that plan would not have met constraints, on-table adaptive replanning using an isotoxicity approach was performed. The primary objective was to demonstrate <15.8% acute grade 3+ gastrointestinal (GI) toxicity definitely related to SMART measured through 90 days and evaluated according to Common Terminology Criteria for Adverse Events v5.0 (CTCAE). All patients have completed 90-day follow-up. Secondary objectives included OS, distant progression free survival (DPFS), and patient-reported quality of life. Results: 136 patients across 13 sites were enrolled between 2019-2021. Mean age was 65.7 years. Head of pancreas lesions were most common (66.9%; n=91). 43.4% (n=59) had BRPC, 56.6% (n=77) LAPC. Mean induction chemotherapy duration was 155.7 days, typically with FOLFIRINOX 65.4% (n=89) or gemcitabine doublet 16.9% (n=23). Mean CA19-9 after induction chemotherapy was 71.7 U/mL. On-table adaptive replanning was used for 93.1% of fractions. SMART was delivered in consecutive days (56.6%) or every other day (43.4%). Median follow-up was 16.4 months and 8.8 months from diagnosis and SMART, respectively. 31.6% (n=43) had surgery after SMART. The incidence of acute grade 3+ GI toxicity definitely and probably related to SMART were 0% and 2.2% (n=3), respectively. 1-year LC and DPFS from SMART were 82.9% and 50.6%, respectively. 1-year OS was 93.9% from diagnosis and 65.0% from SMART. Conclusion: This is the first prospective, multi-institutional study of ablative SMART with prescribed BED10 of 100 Gy delivered in 5 fractions for BRPC/LAPC. The primary objective was met, signaling that further prospective evaluation of ablative SMART for BRPC/LAPC is warranted with a focus on long-term LC and OS compared to chemotherapy alone.
Volume
114
Issue
5
First Page
1062
Last Page
1063
