Phosphate level changes in oral cancer patients – recognizing the risk for refeeding syndrome

Purpose: Patients with oral squamous cell carcinoma (OSCC) often have difficulties in obtaining sufficient nutrition and may develop refeeding syndrome (RFS) during hospitalization. RFS may be fatal if not treated properly. This study clarified changes in perioperative phosphate levels and occurrence of RFS symptoms in OSCC patients to identify clinically notable predisposing factors for RFS in this specific patient population. Methods: A retrospective analysis included primary OSCC patients with microvascular free flap reconstruction. Patients with treatment for additional malignancy, hypoparathyroidism, and missing values of preoperative and/or postoperative plasma phosphate (P-Pi) concentration were excluded. The outcome variable was severe postoperative hypophosphataemia (mmol/l) during the postoperative period (P-Pi < 0.50 mmol/l). Predictor variables were age, sex, smoking, heavy alcohol use, diabetes, body mass index (BMI), weight, height, tumour site, tumour size, tracheostomy, nutritional route, and preoperative P-Pi concentration. Results: Of the 189 patients with primary OSCC, 21 (11%) developed severe hypophosphataemia. Of these patients, 17 (81%) developed RFS symptoms. Higher age (p = 0.01), lower patient height (p = 0.05), and no current smoking (p = 0.04) were significantly associated with postoperative hypophosphataemia. In multivariable regression analyses, higher age (OR 1.06 per year) and age over 70 years (OR 3.77) were independently associated with development of severe hypophosphataemia. Conclusion: Restoration of nutritional balance and close follow-up of electrolyte balance in the perioperative phase are necessary to prevent RFS, especially in patients with oral cancer requiring extensive reconstructions. Special attention should be focused on elderly patients since they are prone to this unnoticeable but potentially life-threatening electrolyte disturbance.