Background

Observational studies suggest that cholesterol-lowering medication (CLM) use is associated with longer recurrence-free survival in breast cancer patients. Since 2007, aromatase inhibitors (AIs) have been guideline treatment for estrogen receptor positive (ER+) postmenopausal breast cancer. AI therapy is associated with increased cholesterol levels. We investigated the association of CLM use and breast cancer recurrence rate in patients treated with AIs.

Methods

This cohort included all women diagnosed with stage I-III ER+ breast cancer from 2007-2016, treated with AI in the adjuvant setting, and registered in the Danish Breast Cancer Group database. We ascertained incident CLM exposure (≥1 prescription post-diagnosis) from the Danish National Prescription Registry and modelled CLM as a time-varying exposure lagged by 6 months. Follow-up began 6 months after diagnosis and continued to the first event of recurrence, death, emigration, 10 years or 25^th September 2018. We estimated recurrence rates, and crude and adjusted hazard ratios (HRs) with 95% confidence intervals (95% CI), comparing CLM exposure with non-exposure.

Results

We enrolled 12,947 eligible patients. Median follow-up was 4.6 years. During follow-up, the total person-years of the unexposed group was 56,171 (incidence rate per 1,000 person-years: 11.50 [95% CI: 10.63–12.42]) and 5,246 in the CLM exposed group (incidence rate per 1,000 person-years: 12.20 [95% CI: 9.40–15.58]). There was little evidence of a protective effect of CLM on breast cancer recurrence during total follow-up but some evidence during the first 5 years (Table).

Conclusions

CLM use was not associated with a substantially reduced risk of breast cancer recurrence among AI users.

Legal entity responsible for the study

Aarhus University Hospital.

Funding

Jeppe Juhl Stiftelsen.

Disclosure

All authors have declared no conflicts of interest.

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