Photodynamic therapy combined with metal stent improve palliative malignant gastric outlet obstruction through regulating immune microenvironment and intestinal flora: a real-world retrospective study

Malignant gastric outlet obstruction (MGOO) is managed through jejunal nutrition tubes, endoluminal stents, or gastrojejunostomy. Photodynamic therapy (PDT) offers rapid tumor reduction with minimal side effects but remains underexplored for MGOO. This study evaluated the efficacy and safety of PDT combined with stenting for MGOO and explored its mechanisms. Peripheral blood, tumor tissues, and fecal samples were collected before and 48 hours after PDT for flow cytometry, immunohistochemistry, RNA sequencing, and fecal 16S sequencing. Among 49 patients (28 Stent+PDT, 21 Stent), the Stent+PDT group showed improved survival (11 vs. 5 months, P=0.004), better GOOSS and KPS scores (P<0.001), and enhanced tumor reduction (P=0.049). PDT boosted immune function, induced M1 macrophage polarization, and altered gene expression and gut microbiota, including increased bifidobacteria. PDT combined with stenting is safe, enhances immune responses, modulates gene expression, and improves outcomes in MGOO patients.