A Single Arm Phase II Study of the Efficacy of Tamoxifen in Triple Negative (oestrogen receptor alpha negative, progesterone receptor negative, HER-2 negative) but Oestrogen Receptor Beta Positive Metastatic Breast Cancer

This study looks at the effectiveness of the drug tamoxifen in treating breast cancer which is classified as triple negative (oestrogen receptor alpha negative, progesterone receptor negative, HER-2 negative) and oestrogen receptor beta positive, where the cancer has spread to distant sites (metastases). Who is it for? You can join this study if you are a woman with triple negative metastatic breast cancer that is oestrogen receptor beta positive and chemotherapy and/or radiotherapy is currently not considered appropriate. Prior to entering the study, a sample of metastatic tumour must be tested and confirmed to be oestrogen receptor beta positive. Trial details Some breast cancer cells contain receptors which the female hormone oestrogen binds to, causing the cancer to grow. The study aims to find out whether tamoxifen may be useful for treating metastatic breast cancer that contains the oestrogen beta receptor. Tamoxifen is an anti-oestrogen drug which is frequently used to treat breast cancers that contain the oestrogen alpha receptor but has not been used specifically to treat breast cancers that contain the oestrogen beta receptor. Participants will all receive one oral tablet (20mg) of tamoxifen daily, unless they suffer unacceptable side effects, or their breast cancer progresses.