The following is a summary of “Effect of Apalutamide on Thyroid Function in Prostate Cancer Patients,” published in the July 2024 issue of Endocrinology by Moffatt, et al.
For a study, researchers sought to characterize the clinical presentation and management strategies for thyroid dysfunction induced by apalutamide (APT) in patients undergoing treatment for prostate cancer.
They conducted a retrospective case series involving 16 patients who developed APT-associated thyroid dysfunction during treatment for prostate cancer at two academic medical centers. They analyzed clinical parameters, thyroid function laboratory results, and thyroid hormone replacement therapy requirements throughout APT treatment.
Among the 16 patients included in the study, 3 had no history of thyroid disease before APT treatment, while 13 had preexisting hypothyroidism. The observed patterns of thyroid dysfunction included both overt and subclinical hypothyroidism. The median time from initiation of APT to detection of abnormal thyroid function tests was 19 weeks, although some cases presented as early as 2 to 4 weeks after starting APT. Management of APT-induced hypothyroidism typically involves initiating or adjusting levothyroxine (LT4) replacement therapy. Patients with preexisting hypothyroidism often required a 2- to 3-fold increase in LT4 dosage during APT to achieve euthyroid status. Among patients who completed or discontinued APT therapy, thyrotropin levels were normalized at a median of 11 weeks post-therapy, with thyroid hormone requirements returning to levels comparable to those before APT initiation.
APT-induced thyroid dysfunction manifests primarily as new-onset or exacerbated hypothyroidism in patients undergoing treatment for prostate cancer. Effective management involves prompt initiation or adjustment of LT4 replacement therapy. Regular monitoring of thyroid function tests every 1 to 2 months during APT treatment and at 2 to 3 months post-therapy cessation is essential to optimize management outcomes for patients with prostate cancer.