Treatment of metastatic gastric adenocarcinoma with image guided high-dose-rate, interstitial brachytherapy as second line or salvage therapy.

PURPOSE To evaluate the safety and efficacy of image guided high-dose-rate interstitial brachytherapy (IBT) concerning the treatment of patients with hepatic, lymphatic and pancreatic metastases originating from gastric cancer - an entity rarely surgically treatable with curative intent. METHODS Twelve patients with a cumulative number of 36 metastases (liver: 29, pancreatic: 2, lymph nodes: 5) from histologically proven gastric adenocarcinoma received treatment with IBT between 2010 and 2016 and were retrospectively analyzed. Every patient underwent palliative chemotherapy prior to the IBT procedure. IBT employs a temporarily, intratumorally placed 192iridium source in a single fraction with the goal of tumor cell eradication. Efficacy was assessed clinically and by acquisition of CT/MRI every three months. RESULTS Local tumor control (LTC) was achieved in 32 (89%) of all treated metastases. Four lesions showed a local recurrence after 7 months. Lesion sizes varied from 9 to 102 mm with a median of 20 mm. The median progression free survival was 6.6 months (range 1.8-46.8 months). The median overall survival was 11.4 months (range 5-47 months). One patient suffered a major complication following IBT - hepatic hematoma and abscess (Common Terminology Criteria for Adverse Events grade 3), successfully dealt with by transcutaneous drainage. CONCLUSION IBT is an overall safe procedure, which facilitates high rates of local tumor control in treatment of metastatic gastric adenocarcinoma. Compared to surgical metastasectomy, similar overall survival rates could be achieved in our patient collective after IBT application.