Elucidating mechanisms of tamoxifen resistance in breast cancer
Estrogen receptor (ER)-positive breast tumours are stimulated by estrogen, and so antiestrogenic therapy has become a fundamental adjuvant therapy for many women with this disease. Tamoxifen is the gold standard for antiestrogen drugs, but residual tumour cells have a knack of developing resistance to tamoxifen, leading to disease recurrence. Overcoming tamoxifen resistance was a major topic at the 21st Annual San Antonio Breast Cancer Symposium [ San Antonio, US; December 1998 ]. Evidence was presented showing that the nature of tamoxifen itself may be the problem, as it has both estrogen-agonist and -antagonist properties.