Pretreatment body mass index as a prognostic factor for clinical course and survival in primary surgically treated oral squamous cell carcinoma – a retrospective study

Abstract

In oral squamous cell carcinoma (OSCC), body mass index (BMI) is an available but imperfect marker of nutritional reserve. Evidence on pretreatment BMI in surgery-based European OSCC cohorts remains limited, especially regarding perioperative outcomes. This study evaluated associations of pretreatment BMI with overall survival (OS), recurrence-free survival (RFS), and perioperative outcomes after curative-intent R0 resection. This retrospective single-center cohort included adult patients with previously untreated primary OSCC, available pretreatment BMI, and curative-intent R0 surgery between 2014 and 2023. BMI was assessed continuously and by World Health Organization (WHO) categories. OS and RFS were analyzed using multivariable Cox regression adjusted for age, sex, pathological T category, nodal status, microvascular free-flap reconstruction, and diabetes mellitus. Perioperative outcomes included red blood cell (RBC) transfusion, RBC units transfused, percutaneous endoscopic gastrostomy (PEG) placement, and intensive care unit (ICU) and hospital length of stay. A total of 274 patients with available pretreatment BMI were included; 116 deaths occurred. Five-year OS ranged from 31.4% in patients classified as underweight to 82.0% in patients with obesity. Higher BMI was associated with lower mortality (HR per 1 kg/m² 0.95, 95% CI 0.91–0.99; p = 0.013), and obesity was associated with improved OS compared with normal weight (HR 0.50, 95% CI 0.26–0.96; p = 0.037). BMI was not significantly associated with RFS after adjustment (HR per 1 kg/m² 0.97, 95% CI 0.93–1.00; p = 0.080). Higher BMI was associated with fewer perioperative RBC transfusions (any transfusion: OR 0.91, 95% CI 0.84–0.98; p = 0.012; number of units: OR 0.89, 95% CI 0.82–0.95; p = 0.001). BMI was not independently associated with PEG placement or hospital length of stay; ICU findings depended on BMI modeling. Higher pretreatment BMI was associated with better OS and lower perioperative RBC transfusion requirements, whereas associations with RFS and most other perioperative outcomes were not significant after adjustment. Given the retrospective design and limitations of BMI as a body-composition marker, these findings should be interpreted cautiously. Pretreatment BMI may help identify low-BMI patients warranting early supportive-care assessment.