An Antiestrogenic Activity Score for tamoxifen and its metabolites is associated with breast cancer outcome.

ABSTRACT:

Purpose

Endoxifen concentrations have been associated with breast cancer recurrence in tamoxifen-treated patients. However, tamoxifen itself and other metabolites also show antiestrogenic anti-tumor activity. Therefore, the aim of this study was to develop a comprehensive Antiestrogenic Activity Score (AAS), which accounts for concentration and antiestrogenic activity of tamoxifen and three metabolites. An association between the AAS and recurrence-free survival was investigated and compared to a previously published threshold for endoxifen concentrations of 5.97 ng/mL.

Patients and methods

The antiestrogenic activities of tamoxifen, (Z)-endoxifen, (Z)-4-hydroxytamoxifen, and N-desmethyltamoxifen were determined in a cell proliferation assay. The AAS was determined by calcul

SUBMITTER: de Vries Schultink AH 

PROVIDER: S-EPMC5812686 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature