Statin use tied to lower breast cancer death risk

Key takeaways:

• Statin use after breast cancer diagnosis may reduce breast cancer mortality risk.
• Breast cancer mortality risk reduction was greatest for those whose cholesterol levels decreased with statin use.

Statin use after breast cancer diagnosis was associated with reduced breast cancer mortality and reduced serum cholesterol levels compared with not using a statin, according to cohort study results published in JAMA Network Open.

“It has been suggested that statins may be beneficial for breast cancer survival in patients with metastatic disease. Moreover, serum cholesterol level may have a role in breast cancer outcome,” Mika O. Murto, MD, general surgeon in the department of general surgery at the Tays Cancer Centre at Tampere University Hospital, Finland, and colleagues wrote. “Oxysterol 27-hydroxycholesterol, the main cholesterol metabolite, promotes tumor growth and metastases in breast cancer mouse models and has been associated with breast cancer mortality in females with low estrogen levels.”

Murto and colleagues conducted a retrospective, population-based cohort study of 13,378 women (median age, 62 years) with newly diagnosed invasive breast cancer in Finland from 1995 to 2013. All participants had available hormone receptor data and at least one measurement of cholesterol.

The primary outcome was breast cancer mortality and overall mortality between the date of breast cancer diagnosis and December 2015.

After a median follow-up period of 4.5 years after breast cancer diagnosis, 16.4% of women died, with 7% dying of breast cancer.

Researchers observed statin use prior to breast cancer diagnosis as a risk factor for breast cancer mortality even after adjusting for total cholesterol level (HR = 1.22; 95% CI, 1.02-1.46; P = .03). However, statin use after diagnosis was associated with a reduced breast cancer mortality risk when adjusting for total cholesterol (HR = 0.85; 95% CI, 0.73-1; P = .05).

Breast cancer mortality risk decreased by more than 50% for women whose cholesterol levels decreased after statin initiation (HR = 0.49; 95% CI, 0.32-0.75; P = .001), but the risk was nonsignificant among those whose cholesterol level did not also decrease.

When adjusting for cholesterol levels, breast cancer mortality risk was about 20% lower among statin users vs. nonusers in each patient subgroup stratified by tumor extent and estrogen receptor, progesterone receptor and ERBB2 status. Among statin users, researchers observed reduced breast cancer mortality for women with estrogen receptor-positive tumors (HR = 0.82; 95% CI, 0.68-0.99; P = .03). Statin users also had lower overall mortality compared with nonusers when adjusting for serum cholesterol levels (HR = 0.8; 95% CI, 0.72-0.88; P < .001).

“This finding suggests that cholesterol-lowering interventions with statins may be beneficial for breast cancer,” the researchers wrote. “Serum cholesterol should be taken into account in future studies on statin use and breast cancer mortality.”