Background: Current NCCN guidelines recommend the use of cetuximab, an EGFR monoclonal antibody, in the treatment of head and neck (H&N) cancers in combination with radiation therapy as initial treatment of locally or regionally advanced disease in patients, who are ineligible
for platinum-based therapy. It is also the standard of care in the treatment of recurrent or persistent disease with distant metastases.
Objective: Hypomagnesemia is a common side effect of cetuximab. Previous studies demonstrated that magnesium reduction was a potential marker of efficacy and outcome in the treatment of advanced colorectal cancer. We hypothesize that hypomagnesemia is also a marker of efficacy of the anti-neoplastic treatment of H&N cancer.
Methods: We retrospectively reviewed the medical records of H&N cancer patients that were treated with cetuximab between January 1, 2006 and January 1, 2016 at the Stratton VA Medical Center. Included in the study were patients aged over 20 years with stage III or IV H&N cancer who received cetuximab. Exclusion criteria included prior magnesium supplementation, history of treatment with anti-EGFR therapy, malabsorption syndromes and genetic magnesium wasting syndrome.
Results: Of the 63 patients studied, 23 developed hypomagnesemia for an overall incidence of 36.5%. The median age of diagnosis was 65 years for the hypomagnesemia group and 66 years for the nonhypomagnesemia. The patients that developed hypomagnesemia had a median survival of 27 months (95% CI, 16.3-37.6) while those that maintained normal magnesium levels had a mean survival of 20 months (95% CI, 12.3-27.7) (P = .583).
Conclusions: To our knowledge, no study has examined the predictive value of hypomagnesemia for the overall survival of H&N cancer patients treated with cetuximab that develop hypomagnesemia vs those that don’t. While data from the colorectal cancer suggest that hypomagnesemia may be used as a surrogate of efficacy for cetuximab, our data negates such correlation. Further study is required to elicit the link between cetuximab and hypomagnesemia.
