(Z)-Endoxifen Reduces Mammographic Breast Density

Follow Drugslib on

By Elana Gotkine HealthDay Reporter

Medically reviewed by Carmen Pope, Senior Medical Editor, B. Pharm. Last updated on May 14, 2026.

via HealthDay

THURSDAY, May 14, 2026 -- (Z)-endoxifen, a tamoxifen metabolite, at doses of 1 and 2 mg yields significant reductions in mammographic breast density (MBD), according to a study published online April 27 in the Journal of the National Cancer Institute.

Per Hall, M.D., Ph.D., from the Karolinska Institutet in Stockholm, and colleagues measured the effect of two different doses of (Z)-endoxifen on MBD in healthy women. A total of 240 healthy premenopausal women were randomly assigned to receive placebo or 1 or 2 mg of (Z)-endoxifen daily for six months (80 in each group).

The researchers found a significant relative change in MBD in both (Z)-endoxifen arms compared with placebo (−19.3 and −26.5 percent in the 1 and 2 mg arms, respectively). The numbers of participants discontinuing due to adverse events related to the investigational medicinal product were four, five, and 11 in the placebo, 1-mg, and 2-mg arms, respectively. Significantly higher scores of vasomotor symptoms were reported for participants receiving 2 mg (Z)-endoxifen versus placebo. There were no clinically significant changes in hematological safety tests or vital signs.

"Both 1 and 2 milligrams of endoxifen resulted in a clear reduction in breast density compared with the placebo," coauthor Mattias Hammarström, also from the Karolinska Institutet, said in a statement. "Our results suggest that a lower dose may be sufficient to affect breast density, whilst also appearing to be better tolerated."

Several authors disclosed ties to Atossa Therapeutics, which funded the study.

Abstract/Full Text

Disclaimer: Statistical data in medical articles provide general trends and do not pertain to individuals. Individual factors can vary greatly. Always seek personalized medical advice for individual healthcare decisions.

Source: HealthDay

Posted : 2026-05-15 02:41

Read more

Disclaimer

Every effort has been made to ensure that the information provided by Drugslib.com is accurate, up-to-date, and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. Drugslib.com information has been compiled for use by healthcare practitioners and consumers in the United States and therefore Drugslib.com does not warrant that uses outside of the United States are appropriate, unless specifically indicated otherwise. Drugslib.com's drug information does not endorse drugs, diagnose patients or recommend therapy. Drugslib.com's drug information is an informational resource designed to assist licensed healthcare practitioners in caring for their patients and/or to serve consumers viewing this service as a supplement to, and not a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners.

The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug or drug combination is safe, effective or appropriate for any given patient. Drugslib.com does not assume any responsibility for any aspect of healthcare administered with the aid of information Drugslib.com provides. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse or pharmacist.

Popular Keywords