CYP19A1 and breast cancer: In a prospective study with a relatively small sample size of 23 women with early-stage breast cancer who were candidates for initiating treatment with aromatase inhibitors [70], no association could be identified between discontinuation of AROi and changes in sleep quality assessment, in sleep disturbance measured by actigraphy, or in reported sleep symptoms (reported by patients according to Common Fund's Patient-Reported Outcomes Measurement Information System (PROMIS) questionnaires) presented after 3 months of AROi treatment.