The following is a summary of “Central Hypothyroidism is Frequent During Mitotane Therapy in Adrenocortical Cancer Patients: Prevalence and Timeline,” published in the September 2023 issue of Endocrinology by Poirier, et al.

Central hypothyroidism, a condition where the thyroid gland doesn’t produce sufficient hormones due to a dysfunction in the pituitary gland or hypothalamus, has been observed in patients treated with mitotane. However, there is limited data available on the prevalence and timing of the condition in mitotane-treated patients. For a study, researchers sought to provide a more comprehensive understanding of thyroid hormone insufficiency in individuals exposed to mitotane.

The researchers conducted a review of the medical records of patients who received mitotane therapy for adrenocortical cancer in two academic centers in Montreal, Canada, and Toulouse, France, between 1995 and 2020. They examined thyroid function parameters during and after mitotane treatment.

In their cohort of 83 patients, 17 were excluded due to preexisting primary hypothyroidism or drug-induced hypothyroidism. During follow-up, out of the 66 remaining patients, 3 maintained normal thyroid function, while 63 developed central hypothyroidism. Among these 63 patients, 56 had inappropriately normal or low thyroid-stimulating hormone (TSH) levels, and 7 had mildly elevated TSH. The onset of hypothyroidism occurred in less than 3 months for 33.3% of patients, 3 to 6 months for 19.1%, 6 to 9 months for 14.3%, and 9 to 12 months for 9.5%. A minimum of 14.3% of cases developed after more than 12 months of mitotane exposure, and in 6 patients, the timing was undetermined. Over time, 27 patients ceased mitotane treatment, and partial (42.3%) or complete (23.1%) recovery from hypothyroidism was observed, predominantly within the first 2 years after stopping mitotane.

The study highlighted that mitotane therapy was significantly associated with the development of central hypothyroidism, with a prevalence of 95.5%. Most cases occurred within the first year of treatment. Partial or complete recovery of thyroid function was seen in 65.4% of cases. The findings emphasized the importance of systematic monitoring of TSH and free T4 levels during and after discontinuing mitotane therapy.

Source: academic.oup.com/jcem/article-abstract/108/9/2336/7059997?redirectedFrom=fulltext