Statins linked to better breast cancer-specific survival
Women with breast cancer who took statins regularly had significantly better breast cancer-specific survival than those who did not take any statins, a Swedish study has shown. [SABCS 2017, poster P2-13-03]
“Given the epidemiological findings from other Scandinavian populations, we hypothesized that statins may have anticancer effects and therefore reduce cancer-related mortality in the Swedish population,” said investigators of the study.
In this retrospective cohort study of 20,559 Swedish women with breast cancer, a total of 4,678 died during follow-up, of which 2,669 cases were considered to be breast cancer-specific deaths.
Compared with irregular users of statins or non-users, women who took statins regularly before breast cancer diagnosis had a 23 percent lower risk of dying from breast cancer (hazard ratio [HR], 0.77; p=0.014). The association became stronger when the comparison was done in diabetes patients (n=545) (HR, 0.63; p=0.044).
Similarly, women who received statins after breast cancer diagnosis had a 17 percent lower risk of dying from breast cancer (HR, 0.83; p=0.001).
The dosage of statins administered before breast cancer diagnosis did not appear to affect the risk of breast cancer-related death. The risk was reduced by 26 percent in women who took an intermediate statin dose, and by 16 percent in those who took a high dose.
In addition, administration of both lipophilic and hydrophilic statins after breast cancer diagnosis was associated with a 7 percent relative risk reduction in breast cancer-related mortality, suggesting that the type of statin administered had no effect on the magnitude of risk reduction.
“Several possible mechanisms may explain the survival benefits observed with statins in patients with breast cancer,” suggested lead investigator Professor Signe Borgquist of Lund University, Lund, Sweden.
“Statins inhibit the enzyme 3-hydroxy-3-methylglutaryl coenzyme A [HMG-CoA] reductase, which is found to be highly expressed in some breast tumours,” she explained. “In a previous Swedish study, high levels of HMG-CoA reductase expression were found to be associated with better outcomes in breast cancer.”
“Apart from inhibition of HMG-CoA reductase, our study also showed that statins decreased the level of a cholesterol metabolite called 27-hydroxycholesterol [27HC],” added Borgquist. “27HC binds to the oestrogen receptor and serves as an oestrogen receptor agonist in breast cancer cells. It is possible that inhibiting the production of cholesterol and 27HC may have a mitigating effect on breast cancer progression and recurrence.”
“We would like to conduct a large trial to prove that statin use provides benefits in patients with breast cancer. The trial will also hopefully identify biomarkers that can predict benefits from statins,” she said.
Borgquist and colleagues are now recruiting 126 patients with advanced breast cancer into the ABC-SE (Advanced Breast Cancer-Statins and Endocrine Treatment) trial, which will evaluate the efficacy and tolerability of atorvastatin in addition to endocrine therapy for treatment of advanced breast cancer in the first- and second-line settings. [https://clinicaltrials.gov/ct2/show/NCT02958852]