The impact of postresection syndrome on tolerability and efficacy of immunotherapy in patients with metastatic gastric cancer: results of a prospective study

Aim of the study – to comprehensively evaluate the impact of postresection syndrome on the tolerability and efficacy of immunotherapy in patients with metastatic gastric cancer and to determine the role of personalized comprehensive rehabilitation in correcting metabolic-nutritional, electrolyte, and psychological impairments in this vulnerable subgroup. Materials and methods. A prospective randomized study (2021–2025) included 168 patients with histologically confirmed stage IV gastric cancer receiving PD-1 inhibitor immunotherapy (pembrolizumab/nivolumab) in the 3rd-4th line. Patients were randomized into an experimental group (n=82): immunotherapy + comprehensive rehabilitation (nutritional support, H 2 /O 2 inhalations, magnetic therapy, psychological correction, electrolyte balance correction); and a control group (n=86): immunotherapy only. Special focus was placed on the subgroup with prior total gastrectomy (n=84). Results. Gastrectomized patients in the experimental group exhibited a pronounced postresection syndrome: baseline PNI 34.66±2.8 (vs. 38.15±3.5 in non-resected, p=0.0047), hypocalcemia (2.05±0.15 mmol/L), hypomagnesemia (0.61±0.09 mmol/L), and chronic pain (78.6 %). After 6 months, the experimental group demonstrated: maximal PNI increase (+21.54 to 56.20, p<0.001), nitrogen balance normalization (+5.2 g/day, p=0.03), Ca² + elevation (to 2.31 mmol/L) and Mg² + recovery (to 0.87 mmol/L) (p<0.05), and significant EORTC QLQ-C 30 improvement (global QoL +15.2 %, physical functioning +14.8 %, pain reduction –55.6 %, p<0.05). Psychological reasons for therapy discontinuation decreased 3.2-fold (OR=0.31). Confirmed progression (iCPD) among patients with unconfirmed progression (iUPD) at week 8 was significantly lower in the experimental group (45.0 % vs. 72.3 %, p=0.05). Conclusions. Patients with a history of gastrectomy constitute a vulnerable subgroup with severe postresection malabsorption, electrolyte deficiency, and nutritional decompensation that impair immunotherapy tolerability and potentially reduce efficacy. Comprehensive rehabilitation integrating metabolic, nutritional, physical, and psychological support effectively restores homeostasis, improves quality of life, and promotes disease stabilization. These findings justify the early integration of personalized rehabilitation programs into clinical standards for this patient category.