Feasibility and Early Clinical Experience of Online Adaptive MR-Guided Radiotherapy of Liver Tumors

Purpose: To assess the feasibility and early results of online adaptive MR-guided radiotherapy (oMRgRT) of liver tumors. Methods: We retrospectively examined consecutive patients with primary or secondary liver lesions treated at our institution using a 0.35T hybrid MR-Linac (Viewray Inc., Mountain View, CA, USA). Online-adaptive treatment planning was used to account for interfractional anatomical changes, and real-time intrafractional motion management using online 2D cine MRI was performed using a respiratory gating approach. Treatment response and toxicity were assessed during follow-up. Results: Eleven patients and a total of 15 lesions were evaluated. Histologies included cholangiocarcinomas and metastases of neuroendocrine tumors, colorectal carcinomas, sarcomas and a gastrointestinal stroma tumor. The median BED10 of the PTV prescription doses was 84.4 Gy (range 59.5–112.5 Gy) applied in 3–5 fractions and the mean GTV BED10 was in median 147.9 Gy (range 71.7–200.5 Gy). Online plan adaptation was performed in 98% of fractions. The median overall treatment duration was 53 min. The treatment was feasible and successfully completed in all patients. After a median follow-up of five months, no local failure occurred and no ≥ grade two toxicity was observed. OMRgRT resulted in better PTV coverage and fewer OAR constraint violations. Conclusion: Early results of MR-linac based oMRgRT for the primary and secondary liver tumors are promising. The treatment was feasible in all cases and well tolerated with minimal toxicity. The technique should be compared to conventional SBRT in further studies to assess the advantages of the technique.

Resección laparoendoscópica de tumor de la unión gastroesofágica

Atypical gastric resection has proved to be beneficial to treat submucosal tumors. The technique is more difficult when these tumors develop next to the gastroesophageal junction (GEJ). Intragastric resection combining endoscopic and laparoscopic approach was proposed to solve this limitation. There are no publications about this technique in our environment. A 42-year-old female patients with a 2-mm subepithelial tumor below the cardia evaluated by upper gastrointestinal (UGI) videoendoscopy and endoscopic ultrasound suggestive of a gastrointestinal stroma tumor (GIST) underwent resection using the combined laparo-endoscopic approach. Under laparoscopic guidance, balloon-tipped trocars were introduced in the abdominal cavity and then into the stomach using endoscopic view. The balloons were inflated to fix the gastirc wall to the abdominal wall. The lesion was resected using mechanical stapler. The combined approach is safe and efficient, and simple to perform for trained professionals, constituting a reproducible option in selected cases