Hair Cortisol Measurement in Mitotane-Treated Adrenocortical Cancer Patients

The only approved drug for the treatment of adrenocortical cancer (ACC) is mitotane. Mitotane is adrenolytic and therefore, hydrocortisone replacement therapy is necessary. Since mitotane increases cortisol binding globulin (CBG) and induces CYP3A4 activity, high doses of hydrocortisone are thought to be required. Evaluation of hydrocortisone therapy in mitotane-treated patients has been difficult since there is no good marker to evaluate hydrocortisone therapy. Measurement of cortisol in scalp hair is a novel method that offers the opportunity to measure long-term cortisol levels. Our aim was to evaluate whether hair cortisol measurements could be useful in evaluating recent hydrocortisone treatment in mitotane-treated ACC patients. Hair cortisol levels were measured in 15 mitotane-treated ACC patients on hydrocortisone substitution and 96 healthy individuals. Cortisol levels were measured in 3 cm hair segments, corresponding to a period of 3 months. Hair cortisol levels were higher in ACC patients compared to healthy individuals (p < 0.0001). Seven ACC patients (47%) had hair cortisol levels above the reference range. None of the patients had hair cortisol levels below normal. In contrast to hydrocortisone doses (beta = 0.03, p = 0.93), hair cortisol levels were associated with BMI (beta = 0.53, p = 0.042). There was no correlation between hair cortisol levels and hydrocortisone doses (beta = 0.41, p = 0.13). Almost half of the ACC patients had high hair cortisol levels, suggesting long-term over-substitution of hydrocortisone in some of the patients, whereas none of the patients was under-substituted. Hair cortisol measurements might be useful in long-term monitoring hydrocortisone treatment in mitotane-treated ACC patients.