Background: Peritoneal metastases (PM) of gastric cancer (GC) are considered a terminal condition, with reported median survival ranging from 2 to 9 months. Standard treatment typically involves systemic chemotherapy alone or combined with targeted therapy or immunotherapy, though efficacy is limited. Pressurized intraperitoneal aerosol chemotherapy (PIPAC) has emerged as a novel technique for treating GC PM, although it remains an experimental treatment under investigation. This study aimed to summarize the outcomes of GC PM treatment with PIPAC from the Lithuanian PIPAC program. Methods: All patients who underwent PIPAC for GC PM at Vilnius University Hospital Santaros Klinikos between 2015 and 2022 were included in this retrospective study. The safety of PIPAC was assessed by postoperative complications according to the Clavien–Dindo classification. Efficacy was evaluated based on the peritoneal carcinomatosis index (PCI), ascites dynamics throughout the treatment, and long-term outcomes. Results: In total, 32 patients underwent 71 PIPAC procedures. Intraoperative and postoperative morbidity related to PIPAC occurred after three (4.2%) procedures. Following PIPAC, there was a tendency towards a decrease in median PCI from 10 (Q1 3; Q3 13) to 7 (Q1 2; Q3 12), p = 0.75, and a decrease in median ascites volume from 1300 mL (Q1 500; Q3 3600) at the first PIPAC to 700 mL (Q1 250; Q3 4750) at the last PIPAC, p = 0.56; however, these differences were not statistically significant. The median overall survival after PM diagnosis was 12.5 months (95% CI 10–17), and the median survival after the first PIPAC procedure was 5 months (95% CI 4–10). Conclusions: PIPAC is a safe and feasible treatment option for GC PM; however, well-designed prospective studies are needed to fully assess its efficacy.

Hepatoid adenocarcinoma is an extremely aggressive special subtype of gastric tumors. It can be lethal as no standard treatment options for this type of gastric cancer exist. Here, we describe a very rare case of a young female on her 21^st week of pregnancy who was diagnosed with stage IV hepatoid adenocarcinoma of the stomach with elevated α fetoprotein (AFP) level. Gene mutation analysis performed by next-generation sequencing identified somatic mutations in the PIK3CA gene. Despite the treatment, patient died 2 months after the initial disease presentation. To our best knowledge, this case represents the first report of pregnancy-associated hepatoid gastric adenocarcinoma with the PIK3CA gene mutations, which can provide further clues for the understanding of molecular features of this type of tumor that can reflect biological behavior and may lead to further effective treatment options.