A meta-analysis of randomized clinical trial data presented at the 2024 San Antonio Breast Cancer Symposium offered an overview of risk-reducing medications for the prevention of primary breast cancer.

At present, certain selective estrogen receptor modulators and aromatase inhibitors hold FDA approval as chemoprevention for primary breast cancer. The reliance on clinical trial data for approval may hamper the expansion of medications in the risk-reducing category.

Researchers conducted a meta-analysis of pooled randomized trial data to identify medications associated with risk reduction in breast cancer. They performed database searches and identified 43 relevant studies on breast cancer prevention with risk-reducing medicines. Lifestyle medications, herbal supplements, and multivitamins were excluded.

The final analysis included 35 studies representing 13 medications: tamoxifen, raloxifene, third-generation selective estrogen receptor modulators (arzoxifene, bazedoxifene, and lasofoxifene), aromatase inhibitors (anastrozole and exemestane), statins (pravastatin, simvastatin, and lovastatin), thiazolidinediones (rosiglitazone and pioglitazone), sulfonylurea, metformin, metformin plus sulfonylurea, fenretinide, tamoxifen plus fenretinide, calcium, and calcium plus vitamin D.

Compared with placebo, six medications demonstrated a reduction in breast cancer risk: sulfonylurea (risk ratio [RR] = 0.18; 95% CI, 0.03-0.9), thiazolidinediones (RR = 0.26; 95% CI, 0.08-0.79), third-generation selective estrogen receptor modulators (RR = 0.46; 95% CI, 0.33-0.66), aromatase inhibitors (RR = 0.5; 95% CI, 0.39-0.66), raloxifene (RR = 0.63; 95% CI, 0.47-0.84), and tamoxifen (RR = 0.76; 95% CI, 0.65-0.88).

“The network meta-analysis showed no significant inconsistency, indicating agreement between direct and indirect comparisons of medications, and between-study heterogeneity was low. Notably, third-generation selective estrogen receptor modulators (RR = 0.61; 95% CI, 0.42-0.89) and aromatase inhibitors (RR = 0.67; 95% CI, 0.49-0.9) showed greater efficacy than tamoxifen.”

-Ghazaleh Pourali, MD, postdoctoral research associate at Washington University School of Medicine in St. Louis, and colleagues

The numbers needed to treat were 43.9 for sulfonylurea, 48.6 for thiazolidinediones, 67.3 for third-generation selective estrogen receptor modulators, 73 for aromatase inhibitors, 96.9 for raloxifene, and 149.7 for tamoxifen.

Compared with placebo, a secondary analysis for invasive breast cancer found that aromatase inhibitors (RR = 0.48; 95% CI, 0.33-0.71), raloxifene (RR = 0.63; 95% CI, 0.47-0.86), and tamoxifen (RR = 0.63; 95% CI, 0.51-0.78) were effective for prevention. However, the network meta-analysis inconsistency was significant (P = .01), with moderate between-study heterogeneity (I² = 58.8%).

“Findings can guide future research in breast cancer prevention, as well as clinical considerations and guidelines on breast cancer chemoprevention.”

-Pourali and colleagues

Reference:
https://sabcs.org/Portals/0/Documents/Formatted_Abstracts%2011-27%20Without%20Embargoed.pdf?ver=qjVzk5LPNjOteEIvNEYJFw%3d%3d

Disclosures: MD /alert could not confirm financial disclosures at the time of reporting.

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