Cholesterol synthesis is involved in the assembly and maintenance of cell membranes, modulating their function and fluidity, and it is a precursor for biosynthesis of estrogen. In high levels, estrogen is a mammary gland carcinogen that has been associated with increased risk of breast cancer. Past studies have evaluated the association between use of statins and breast cancer mortality, but most did not consider the underlying cholesterol level. To learn more about this potential association, Dr Mika Murto and colleagues conducted a retrospective, population-based cohort study of 13,378 Finnish women diagnosed with breast cancer to investigate the association between serum cholesterol, statin use, and breast cancer mortality among women.
The investigators found an association between the timing of statin use and risk of breast cancer death. Prediagnostic statin use was associated with an increased risk of breast cancer mortality and overall death compared with nonuse. Conversely, postdiagnostic use of statins was associated with reduced breast cancer mortality and overall death compared with nonuse, and the risk was associated with subsequent decrease in serum cholesterol level. These findings may reflect worse overall health in women with prediagnostic statin use, given that statins are commonly used in secondary prevention of cardiovascular diseases.
In subgroup analyses, these associations were not affected by hormone receptor status or participation in mammography screening, but the risk difference was statistically significant in estrogen receptor-positive cases. Tumor extent also impacted the risk association, with reduced risk in women with localized tumor extent at diagnosis and increased mortality risk among those with metastatic disease and statin use compared with nonuse. Elevated serum cholesterol was not associated with risk of breast cancer mortality after adjusting for statin use.
The findings of this study suggest that cholesterol-lowering interventions with statins may be beneficial for women with breast cancer. Since the risk of mortality was associated with subsequent decreases in serum cholesterol level, the authors propose that serum cholesterol be factored into future studies investigating the effect of statin use on breast cancer mortality among women.
The results of this study suggest that the use of statins to lower cholesterol may be most beneficial in women with early-stage breast cancer. On the basis of this insight, clinicians should consider cholesterol-lowering interventions with statins to help reduce the risk of breast cancer mortality among women in this patient population.