A significant association between statins and survival rates of triple-negative breast cancer (TNBC) patients has been found by researchers from The University of Texas MD Anderson Cancer Center. Their study suggests that since statins are low in cost, easy to access, and produce minimal side effects, these drugs could have an important impact on outcomes for this aggressive form of breast cancer.
The authors write that: “In our analysis we observed a strong association between new onset statin therapy post-diagnosis and improved outcomes among individuals with TNBC. TNBC accounts for 10-20% of all breast cancer diagnoses and is associated with poor prognosis due to the high rate of distant metastases, more limited effective treatment options, poor response rates, and poor treatment durability.”
The study, led by Kevin Nead, MD, was published today in Cancer. While there is previous evidence of an association between breast cancer prognosis and statin use, these researchers say this is the first study adequately powered to investigate this topic specifically for TNBC.
The retrospective study selected patients included in the Surveillance, Epidemiology, and End Results (SEER)-Medicare registry and the Texas Cancer Registry (TCR)-Medicare, two large databases of administrative claims of Medicare-eligible patients. Patients were required to have Medicare Part D prescription coverage to determine their statin use.
This research included 23,192 patients with stage I-III breast cancer, of which 2,281 started a statin within one year following diagnosis (incident statin-users) and 20,911 did not. The median follow-up was 4.4 years for overall survival and 3.3 years (range 0.1-8 years) for breast cancer specific survival. There were 5,327 overall deaths with 1,038 due to breast cancer. The 5-year cumulative estimates of breast cancer specific deaths were 6.0% and 6.8% for incident statin-users and non-statin-users (P=.10), respectively.
The team found a 58% relative improvement in breast cancer-specific survival and a 30% relative improvement in overall survival with statin use. The median follow-up was 3.3 years for breast cancer-specific survival and 4.4 years for overall survival.
“There is already a body of literature on statins and breast cancer and the results have been inconsistent,” Nead said. “Previous research has looked at breast cancer as only one disease, but we know there are many subtypes of breast cancer and we wanted to focus our research on this particularly aggressive form of breast cancer that has limited effective treatment options.”
TNBC is an aggressive disease that makes up roughly 10% to 20% of breast cancer diagnoses. This type of breast cancer does not have any of the receptors that are commonly found in the disease — estrogen or progesterone receptors or HER2 positivity. This results in a highly aggressive breast cancer with poor prognosis and limited treatment options since there are few receptors to actively target with existing therapies.
Of the 23,192 patients enrolled, 2,281 were “incidental statin users,” meaning they started a statin within one year following their breast cancer diagnosis. The incidental statin users were 78.1% white, 8.9% Black, 8.4% Hispanic and 4.5% other.
Analysis by breast cancer stage suggested that the association of incidental statin use with improved outcomes may be stronger in women with early stage TNBC. When examining statin intensity, high-intensity statin use had the strongest effect on overall survival among women with TNBC. Researchers also found a statistically significant association between lipophilic statins (L-statin: simvastatin, atorvastatin, lovastatin, fluvastatin, pitavastatin) and improved overall survival.
“We know that statins decrease breast cancer cell division and increase cell death,” Nead said. “Our study shows that there is an association between statins and improved outcomes in TNBC, and it is time to pursue this idea further in a prospective trial.”