Low-Dose Tamoxifen for Mammographic Density Reduction: A Randomized Controlled Trial

Area of Science:

• Oncology
• Pharmacology
• Radiology

Background:

• Tamoxifen is a crucial drug for breast cancer prevention and adjuvant treatment.
• Mammographic density changes serve as a reliable indicator of response to tamoxifen therapy.
• Investigating lower tamoxifen doses is essential for optimizing treatment efficacy and minimizing adverse effects.

Purpose of the Study:

• To determine if lower doses of tamoxifen are noninferior to the standard 20 mg dose in reducing mammographic density.
• To assess if reduced doses of tamoxifen are associated with fewer treatment-related symptoms.
• To evaluate the efficacy and tolerability of varying tamoxifen doses in a diverse patient population.

Main Methods:

• A 6-month, double-blind, randomized, placebo-controlled, six-arm phase II trial (KARISMA) was conducted.
• 1,439 women aged 40-74 were enrolled, with 1,230 in the intention-to-treat analysis.
• The primary outcome measured mammographic density reduction compared to the 20 mg tamoxifen group, with a noninferiority margin of 17%.

Main Results:

• Doses of 2.5, 5, and 10 mg of tamoxifen demonstrated noninferior mammographic density reduction compared to the 20 mg group, particularly in premenopausal women.
• Severe vasomotor symptoms were reduced by approximately 50% in the 2.5, 5, and 10 mg tamoxifen groups versus the 20 mg group.
• Premenopausal women experienced comparable breast density reduction with 2.5 mg tamoxifen and fewer side effects.

Conclusions:

• The 2.5 mg dose of tamoxifen showed noninferiority in reducing breast density among premenopausal women, with a notable decrease in side effects.
• Lower tamoxifen doses may offer a more tolerable alternative for breast cancer prevention and adjuvant therapy.
• Further research is warranted to confirm if 2.5 mg tamoxifen can effectively reduce the risk of primary breast cancer.