Certain groups of patients with breast cancer experienced a decrease in breast cancer-specific mortality after starting cholesterol-lowering drugs.
Patients with breast cancer who used statins (drugs used to lower cholesterol) tended to have reduced breast cancer-related mortality compared to patients who did not use statins, according to research published in JAMA Network Open.
The study analyzed data from more than 13,000 Finnish women diagnosed with breast cancer between January 1995 and December 2013. A total of 980 patients in the study started statin use after being diagnosed with breast cancer — 781 of whom experienced a decrease in cholesterol, while cholesterol levels remained similar or increased in the other 199 patients.
The average follow-up time was 4.5 years (range, 2.4 to 9.8 years). Within that time, 16.4% of patients died, including 7% who died of breast cancer.
After adjusting for cholesterol level, the use of statins before breast cancer diagnosis was associated with an increased risk of breast cancer.
The group of patients who started statins and saw a decrease in their cholesterol experienced a “robust” reduction in the risk of breast cancer death, though there was no significant decrease in death risk for those whose cholesterol did not decrease after statin initiation, the researchers explained. Additionally, overall mortality was lower among patients who used statins compared to those who did not use statins.
This is not the first study to show that statins may affect breast cancer survival. A 2021 study found that statin use led to a slight decrease in the five-year estimate of breast cancer-specific death. The difference in breast cancer-related death was statistically significant (meaning that researchers can say with a certain degree of confidence that the intervention led to improved outcomes) in patients with triple-negative breast cancer.
Interestingly, this latest study found the opposite: statin use was associated with a decrease in breast cancer-related death for patients with hormone receptor-positive disease, but not triple-negative disease. The Finnish researchers also discovered that the decreased risk of death was observed only in patients with localized disease. In patients with metastatic disease — meaning that it has spread to other parts of the body — statin users tended to have an increased risk of death.
“Thus, statins may be beneficial only in females with early-stage (breast cancer),” the researchers wrote. “On the other hand, patients with metastatic disease have worse outcomes overall. It is plausible that interventions such as statins are unlikely to change the course of disease at this time.”
Statins work by inhibiting the HMG-CoA reductase enzyme, which could potentially interfere with cancer cells directly or indirectly, according to the researchers. Prior mouse models have also shown that one of the main byproducts of cholesterol may promote tumor growth and spread.
“In (breast cancer) cells, statins have anti-invasive and antiangiogenic (stopping tumor growth by blocking blood vessels supplying them) and induce apoptosis (cell death) through HMG-CoA reductase inhibition.”
That said, the researchers speculate that serum cholesterol levels may be a key player in breast cancer outcomes.
“This finding suggests that serum cholesterol may be an important factor in (breast cancer) and that the previously reportedinverse association between statin use and BC mortality is likely mediated by underlying cholesterol level changes,” they wrote in the study.
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