Diagnostic evaluation of simulation CT images for adjuvant radiotherapy in pancreatic adenocarcinoma.

Objective: The purpose of this study is to review simulation CT scans and evaluate their diagnostic value in patients treated with adjuvant radiotherapy for pancreatic adenocarcinoma. Methods: 73 patients who had undergone simulation CT scans for adjuvant radiotherapy in pancreatic adenocarcinoma were reviewed. All simulation CT scans were reviewed by professional abdominal radiologists, who compared the images with corresponding prior CT scans to identify new lesions. Newly detected cancer-related lesions were classified into one of three categories: distant metastasis, locoregional recurrence and indeterminate lesions. Indeterminate lesions were reviewed for malignancy during follow-up imaging work-ups. Results: Of 73 patients, distant metastasis, locoregional recurrence and indeterminate lesions were found in 4 (5.5%), 5 (6.8%) and 32 patients (43.8%), respectively. Among 32 indeterminate lesions, 24 (75.0%) were soft tissue lesions neighbouring the superior mesenteric vessels. Follow-up PET-CT and diagnostic CT scans revealed that 43.7% of indeterminate lesions were malignant presenting local failures. The 3-year overall survival was significantly higher among patients who had no cancer-related lesions than among who did have such findings (44.8% vs 10.8%, p = 0.002). Conclusion: Professional review of simulation CT scans have ample diagnostic value as they help detect early progressions or potential failures in patients treated with adjuvant radiotherapy for pancreatic adenocarcinoma. Simulation CT scans should be carefully reviewed before the delivery of adjuvant radiotherapy. Advances in knowledge: Generally, simulation CT scan has been known to provide limited diagnostic values and clinical impact. However, the results of this study showed a high detection rate of cancer-related lesions, which could potentially affect subsequent treatment strategies in patients with pancreatic adenocarcinoma.