Failure to Achieve 70% of Recommended Protein Intake at One Year Predicts 13-Fold Higher Mortality After Gastrectomy

<b>Background and Aims:</b> Gastric cancer remains a major health burden in East Asia. Gastrectomy is a primary treatment, yet postoperative malnutrition-particularly inadequate protein intake-adversely affects outcomes. This study assessed the association between achieving ≥70% of the recommended protein intake one year after gastrectomy and three-year survival. <b>Methods:</b> In this prospective, single-center, observational study, 69 patients with newly diagnosed gastric cancer who underwent gastrectomy between January 2021 and August 2023 were enrolled. Four patients who died within one year postoperatively were excluded, leaving 65 patients for analysis. Protein intake achievement rate (PIAR) at 12 months was calculated based on a recommended intake of 1.2 g/kg/day, and patients were stratified as PIAR ≥ 70% or <70%. Overall survival was analyzed using time-to-event methods, with a median follow-up of 2.1 years. <b>Results:</b> Among the 65 patients (median age 62 years, IQR 56-68; 56.9% male), 75.4% underwent subtotal gastrectomy. At 12 months, 7 patients (10.8%) failed to achieve a PIAR ≥ 70%. Compared with patients achieving adequate protein intake, those with inadequate intake more frequently underwent total gastrectomy (71.4% vs. 19.0%, <i>p</i> = 0.008) and had advanced-stage disease (Stage III-IV: 85.7% vs. 39.7%, <i>p</i> = 0.039). Kaplan-Meier analysis demonstrated significantly lower survival in the inadequate protein group, with a hazard ratio of 13.02 (95% CI 2.53-66.93); the wide confidence interval reflects the small number of patients with inadequate intake (n = 7). <b>Conclusions:</b> Failure to achieve ≥70% of recommended protein intake one year after gastrectomy is a strong independent predictor of mortality, associated with a 13-fold higher risk of death. Nutritional monitoring and early intervention are crucial, particularly for patients with total gastrectomy or advanced disease.