Researchers have found that ablative stereotactic magnetic resonance (MR)-guided adaptive radiation therapy may improve local control and overall survival in patients with borderline resectable and locally advanced pancreatic ductal adenocarcinoma, according to a recent study published by Chuong et al in Radiotherapy & Oncology. The findings indicated that the strategy may offer encouraging overall survival and limited toxicity.
Background
“Pancreatic ductal adenocarcinoma is a leading cause of cancer death. Surgery is the only known curative treatment, although most newly diagnosed patients are not surgical candidates due to locally extensive and/or distant metastatic disease,” stressed lead study author Michael D. Chuong, MD, Vice Chair and Medical Director of Proton Therapy and Photon Therapyin the Department of Radiation Oncology at the Miami Cancer Institute at Baptist Health South Florida. “Ablative radiation therapy may benefit patients with advanced pancreatic ductal adenocarcinoma by improving [local control], reducing pain, and enhancing quality of life,” he added.
Study Methods and Results
In the prospective, multicenter, single-arm, open-label phase II SMART trial, the researchers recruited 136 patients across 13 centers in three countries after they received ≥ 3 months of any chemotherapy without distant progression and a serum carbohydrate antigen tumor marker level of 500 U/mL. The researchers assigned the patients to receive stereotactic MR-guided adaptive radiation therapy on a 0.35T MR-guided system prescribed to 50 Gy in five fractions. Surgery and chemotherapy were permitted following stereotactic MR-guided adaptive radiation therapy.
They discovered that the median overall survival from diagnosis and stereotactic MR-guided adaptive radiation therapy was 22.8 months and 14.2 months, respectively. The 2-year overall survival rates among all of the patients involved in the study from diagnosis and stereotactic MR-guided adaptive radiation therapy were 53.6% and 40.5%, respectively—which proved to be significantly higher than overall survival expected following chemotherapy with or without standard radiation therapy. Additionally, the 2-year estimated overall survival rates among the patients with resected vs unresected pancreatic ductal adenocarcinoma from stereotactic MR-guided adaptive radiation therapy were 67% vs 26%, respectively.
The 2-year local control rates from diagnosis and stereotactic MR-guided adaptive radiation therapy among all of the patients were 77.7% and 78.2%, respectively, and were higher among patients with resected vs unresected tumors (90% vs 71%, P = .019).
Conclusions
“The SMART trial is the first to prospectively demonstrate the safety of delivering ablative radiation dose for advanced [pancreatic ductal adenocarcinoma], which resulted in excellent long-term [local control] even among patients who did not have surgery,” underscored Dr. Chuong. “We are especially excited by the potential for ablative radiation therapy to also prolong [overall survival]. A phase III randomized trial evaluating whether [overall survival] is definitely improved with addition of ablative SMART to chemotherapy vs chemotherapy alone for advanced [pancreatic ductal adenocarcinoma] is warranted,” he concluded.
Disclosure: For full disclosures of the study authors, visit thegreenjournal.com.
