Abstract
A male patient in his 60s with large squamous cell
carcinoma of the floor of the mouth was scheduled for
tumor resection and free-flap reconstruction. Preoperative
chemotherapy （cetuximab） was discontinued
because of an infusion reaction, and surgery was performed.
During tumor manipulation, electrocardiography
showed sudden tachycardia and T-wave elevation,
with potassium levels rapidly increasing to 6.0 mmol/
L. Considering possible potassium release from tumor
cells into the bloodstream, diuretics and glucose–insulin
therapy were promptly initiated. Potassium levels
were controlled, allowing the continuation of surgery
and successful tumor excision. Post-excision hyperkalemia
recurrence was not observed, and the procedure
was completed. The interior of large tumors is prone
to necrosis because of reduced blood flow. During manipulation,
resecting a large tumor without achieving
preoperative chemotherapy-induced tumor shrinkage
can release tumor cell-derived potassium and metabolic
products into the bloodstream, similar to that in
tumor lysis syndrome. Therefore, the surgical team
must ensure the safe completion of the procedure.
