The differences in findings might be attributed to heterogeneity of studies such as variations in age groups between studies, use of wide range of neuropsychological tests, type of control groups (e.g., breast cancer vs non‐cancer controls not using any endocrine therapy), and treatment groups (for example, some studies pooled aromatase inhibitor and tamoxifen users in one treatment group).34 This evidence concerns the gene CYP19A1 and breast carcinoma.