Exacerbation of metastatic disease shortly after administration of tamoxifen in ER negative advanced breast carcinoma. A case report.

In a patient with long untreated slow-growing osteoblastic bone metastases from an ER/PgR negative breast carcinoma, new metastatic sites in many lymphnodes pleura and massively in liver have been observed 4 weeks after receiving tamoxifen. Cause-effect relationship between administration of the drug and this unusually rapid spreading of the disease may be considered only as a hypothesis, as it is based wholly on clinical outcome. However, reporting of any exacerbation of breast cancer apparently induced by tamoxifen, even if only anecdotal, is advisable.