Hypomagnesaemia in patients with metastatic colorectal carcinoma treated with cetuximab.

BACKGROUND/AIMS: Cetuximab is a chimeric antibody registered for the therapy of advanced colorectal carcinoma. Among the side-effects of cetuximab hypomagnesaemia has been described, but the information is still limited. METHODOLOGY: We have evaluated retrospectively serum magnesium, potassium, calcium, creatinine and albumin in 51 consecutive patients with metastatic colorectal carcinoma treated with cetuximab, mostly combined with irinotecan-based combination chemotherapy. RESULTS: A significant decrease of serum magnesium, potassium, calcium and corrected serum calcium, creatinine and albumin concentrations was already evident one week after the start of treatment. Hypomagnesaemia of any grade was detected in 56% of evaluable patients, but grade 3 or grade 4 hypomagnesaemia was observed in 6% and 4% of patients, respectively. Grade 1 hypokalemia was detected in 47%, grade 3 in 17% and grade 4 hypokalemia was detected in 6% of the patients. Among evaluable patients grade 1 hypocalcaemia was detected in (36%), grade 2 hypocalcaemia in 42%, grade 3 in 4% and grade 4 in 13% of patients. Baseline hypocalcaemia of grade 1 or higher was associated with significantly inferior survival. CONCLUSIONS: Asymptomatic hypomagnesaemia, hypokalemia and hypocalcaemia are common in metastatic colorectal carcinoma patients treated with cetuximab. Hypocalcaemia is a predictor of poor prognosis.