The Geriatric Nutritional Risk Index Predicts Short‐ and Long‐Term Outcomes in the Oldest‐Old With Colorectal Cancer: A Multi‐Institutional Analysis of 225 Nonagenarians

ABSTRACT Aim Surgical outcomes for colorectal cancer (CRC) in nonagenarians remain uncertain due to frailty, comorbidities, and malnutrition. The Geriatric Nutritional Risk Index (GNRI) is associated with surgical outcomes in older patients with CRC, but its prognostic value in nonagenarians is unclear. This study evaluated the GNRI's predictive value for short‐ and long‐term surgical outcomes in this population. Methods We retrospectively analyzed 225 nonagenarians undergoing surgical resection of CRC at 15 institutions between 2011 and 2022. Patients were stratified by GNRI‐high/low status using two cutoffs: 98 (Cohort 1) and 86 (Cohort 2). Outcomes included postoperative complications, length of hospital stay, and overall survival (OS). Stabilized inverse‐probability‐of‐treatment weighting (IPTW) was used to adjust for measured confounding. Results The median age was 92 years (female, 64.9%; colon cancer, 79.6%). GNRI‐high patients had higher body mass index and albumin levels. Complication rates did not differ between the groups. After adjustment, GNRI‐high patients in Cohort 1 had a shorter expected hospital stay (ratio 0.70, 95% CI 0.51–0.96; p = 0.025) but no significant OS difference. In Cohort 2, GNRI‐high patients had better OS ( p < 0.01), confirmed by adjusted Cox models (HR 0.54, 95% CI 0.35–0.82; p < 0.01). Conclusions Preoperative GNRI was associated with hospital stay and OS in nonagenarians undergoing CRC surgery, although the OS association was significant only with the cohort‐derived cutoff of 86, which requires external validation, and not with the literature‐based cutoff of 98. The GNRI is a simple tool to stratify surgical risk and optimize perioperative nutritional status in this vulnerable population.