Possible involvement of zinc deficiency in epidermal growth factor receptor inhibitor-induced xerotic dermatitis.

Cancer treatment with epidermal growth factor receptor inhibitors (EGFRIs) often induces severe xerotic dermatitis. Various irritants facilitate development of dermatitis in xerotic skin. As zinc deficiency plays a role in the development of irritant dermatitis, we measured serum zinc levels in 25 patients with xerotic dermatitis due to treatment with EGFRIs. Of these patients, nine were treated with EGFR tyrosine kinase inhibitors and 16 were treated with anti-EGFR antibody alone or in combination with other anticancer agents. Serum zinc levels of all patients were lower than the normal range of >80 μg/dL, with a mean ± SD serum zinc level of 56.4 ± 11.7 μg/dL. These were correlated with serum magnesium levels in patients. As the serum magnesium level is known to be reduced by the inhibition of EGFR, a similar mechanism may also be involved in decreasing the serum zinc level. Among 21 patients treated with zinc supplementation for more than 2 months, xerotic dermatitis markedly improved, with an increase of serum zinc levels in 16 patients. The other five patients exhibited no significant improvement in their skin condition, and insufficient and unstable increase in serum zinc levels. In conclusion, zinc supplementation may be beneficial in supportive care for patients with EGFRI-induced xerotic dermatitis.