Risk-reducing medications for primary breast cancer: a network meta-analysis

Area of Science:

• Oncology
• Pharmacology
• Preventive Medicine

Background:

• Breast cancer is a leading cause of cancer-related mortality in women.
• Cancer prevention agents (CPAs) offer a strategy to mitigate breast cancer risk.
• Key CPAs include selective estrogen receptor modulators (SERMs) and aromatase inhibitors (AIs).

Purpose of the Study:

• To evaluate the efficacy and acceptability of single CPAs for primary breast cancer prevention in high-risk, unaffected women.
• To rank CPAs based on their effectiveness and tolerability using network meta-analysis.

Main Methods:

• Systematic search of multiple databases and clinical trial registries for relevant randomized controlled trials (RCTs).
• Inclusion of RCTs involving women at elevated risk for breast cancer, treated with CPAs.
• Data extraction and risk of bias assessment, followed by conventional and network meta-analyses.

Main Results:

• Aromatase inhibitors (AIs) significantly reduced breast cancer risk (53%) compared to placebo, with high-certainty evidence.
• Selective estrogen receptor modulators (SERMs), specifically tamoxifen, also reduced risk but were associated with increased endometrial cancer and thromboembolism risks.
• AIs showed potential for slightly greater breast cancer risk reduction than tamoxifen, but with limited long-term toxicity data.

Conclusions:

• CPAs are effective in reducing breast cancer incidence among high-risk women.
• AIs demonstrate superior efficacy and a better safety profile regarding endometrial and thromboembolic events compared to SERMs.
• Further research is needed to fully understand the long-term benefit-risk ratio of CPAs for breast cancer prevention.