Importance of magnesium sulfate supplementation in the prevention of hypomagnesemia and hypocalcemia during chemoradiation in head and neck cancer

In advanced squamous cell carcinoma of the head and neck, concomitant radiotherapy with cisplatin and/or cetuximab is frequently combined with cisplatin-based induction chemotherapy, which can cause severe hypomagnesemia, hypocalcemia, and hypokalemia. The aim of our study was to analyze the effects of magnesium sulfate supplementation on the incidence of hypomagnesemia, hypokalemia, and hypocalcemia during four cycles of TPF (docetaxel, cisplatin, and 5-fluorouracil) induction chemotherapy followed by concomitant radiotherapy (CRT) with cisplatin and cetuximab. Twenty-five patients included in a phase II prospective study received routine magnesium sulfate infusions before each cycle of cisplatin, and additional supplementation based on laboratory findings. During TPF, the incidence of grade 1/2 and grade 3/4 hypomagnesemia was 16% and 4%, respectively; and increased despite magnesium supplementation during CRT to 72% and 8%, respectively. During TPF, a grade 2 and grade 4 hypocalcemia occurred in 8% and 4%, respectively; and during CRT, it reached 36% (grade 1/2). Grade 1 hypokalemia only was observed during TPF (4%) and CRT (8%). The median amounts of supplemented magnesium sulfate during TPF and CRT were 20 mEq and 50 mEq, respectively. It appears that a low incidence of grade 3/4 hypomagnesemia and hypocalcemia in our patients resulted from intensive magnesium supplementation. Thorough measurements of magnesium and calcium during cisplatin-based chemoradiation protocols in patients with head and neck cancer are crucial in preventing the development of grade 3/4 hypomagnesemia and hypocalcemia.