A new study has reported that pterostilbene, a bioavailable stilbenoid found in blueberries, has additive effects when combined with tamoxifen in estrogen receptor positive (ER+) breast cancer cells. Tamoxifen is widely used for the treatment of ER+ breast cancer. Pterostilbene has been found to inhibit breast cancer growth in the laboratory.
In the study, two ER+ breast cancer cell lines, MCF-7 and ZR-751, were pretreated with graduated doses of pterostilbene for 24 hours, followed by treatment with 5 ìmol/L tamoxifen. Cell viability and cell death were evaluated.

Study Results

MCF-7 cells were found to have reduced viability at all time points when pterostilbene was combined with tamoxifen. Similarly, ZR-751 cells displayed additive reductions in cell viability.
Cell death detection tests indicated increased apoptosis (a type of cell death initiated to rid the body of defective and other unwanted cells) in both cell populations.
The authors conclude that pterostilbene has an additive inhibitory effect on breast cancer cells when combined with tamoxifen, most likely from increased cancer cell apoptosis.
Please see our article on what to eat during tamoxifen treatment for more information on how to optimize treatment with tamoxifen and reduce side effects.