Off-label use of tamoxifen in a Chinese tertiary care hospital

Background Tamoxifen is an estrogen receptor modulator used for the treatment of breast cancer; however, currently, it is used in many off-label indications. Objective To investigate the prevalence of tamoxifen off-label prescribing and explore available scientific evidence that supports those uses in outpatients. Setting Xiamen maternity and child health care hospital in Xiamen city of China. Method All the prescriptions of outpatients receiving tamoxifen were exported from an electronic prescribing system during a 1-year period. Tamoxifen use was then classified as either on- or off-label according to the criteria we established previously, and the details of the off-label prescriptions were collected. Logistic regression was applied to explore predictive variables. Evidence search was limited to Up-To-Date, the Micromedex database and PubMed. Main outcome measure The rate of off-label use, risk factors identified by logistic regression and evidence exhibition. Results A total of 75% of all the prescriptions available were classified as off-label use. Hyperplasia of the breast was the most frequently prescribed off-label indication. According to the analysis of logistic regression, male patients, patients less than 34 years old, and physicians with a higher professional title were more likely associated with off-label prescribing. After a search in Up-To-Date, the Micromedex database and PubMed, only male infertility, atypical hyperplasia, mastodynia, peripheral precocious puberty and gynecomastia were found to have strong evidence supporting the use of tamoxifen off-label (22.75%). Conclusion Although the off-label use of tamoxifen was common in our hospital, there was a relative shortage of evidence available supporting those uses.