Carpal tunnel syndrome associated with the use of aromatase inhibitors in breast cancer

Aromatase inhibitors (AI) inhibit peripheral conversion of androgens to estradiol and are commonly used as hormonal therapy for postmenopausal women with hormone receptor-positive breast cancer in the metastatic and adjuvant settings. Joint-related symptoms, however, are seen in a significant proportion of patients. Carpal tunnel syndrome (CTS) is a common nerve entrapment disorder affecting the median nerve. We describe 6 patients with newly diagnosed CTS after initiation of adjuvant AI therapy. Aromatase inhibitors were discontinued in several patients secondary to this toxicity with some switching to tamoxifen and most subsequently experiencing relief of their symptoms. Potential pathophysiologic roles of hormonal manipulation with AIs and other risk factors that might contribute to CTS are discussed. Aromatase inhibitors might accentuate the occurrence of CTS and potentially other nerve entrapment syndromes, and a more systematic approach should be used to better understand the clinical significance and incidence of these symptoms.