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Background Accumulating evidence suggests that statins affect diseases other than cardiovascular disease, including cancer, and that these effects may depend on the lipid solubility of specific statins. Though many studies have reported an association between statin use and breast cancer incidence, the relationship between statin use and breast cancer recurrence has not been well studied. Methods We conducted a nationwide, population-based prospective cohort study of all female residents in Denmark diagnosed with stage I-III invasive breast carcinoma who were reported to the Danish Breast Cancer Cooperative Group registry between 1996 and 2003 (n = 18 769). Women were followed for a median of 6.8 years after diagnosis. Prescriptions for lipophilic and hydrophilic statins were ascertained from the national electronic pharmacy database. Associations between statin prescriptions and breast cancer recurrence were estimated with generalized linear models and Cox proportional hazards regression with adjustment for age and menopausal status at diagnosis; histological grade; estrogen receptor status; receipt of adjuvant therapy; type of primary surgery received; pre-diagnosis hormone replacement therapy; and co-prescriptions of aspirin, angiotensin-converting enzyme inhibitors, nonsteroidal anti-inflammatory drugs, or anticoagulants. All statistical tests were two-sided. Results Most prescriptions for lipophilic statins in the study population were for simvastatin. Exclusive simvastatin users experienced approximately 10 fewer breast cancer recurrences per 100 women after 10 years of follow-up (adjusted 10-year risk difference = -0.10, 95% confidence interval = -0.11 to -0.08), compared with women who were not prescribed a statin. Exclusive hydrophilic statin users had approximately the same risk of breast cancer recurrence as women not prescribed a statin over follow-up (adjusted 10-year risk difference = 0.05, 95% confidence interval = -0.01 to 0.11). Conclusions Simvastatin, a highly lipophilic statin, was associated with a reduced risk of breast cancer recurrence among Danish women diagnosed with stage I-III breast carcinoma, whereas no association between hydrophilic statin use and breast cancer recurrence was observed.

Introduction Chronic diseases and their complications may increase breast cancer risk through known or still unknown mechanisms, or by shared causes. The association between morbidities and breast cancer risk has not been studied in depth. Methods Data on all Danish women aged 45 to 85 years, diagnosed with breast cancer between 1994 and 2008 and data on preceding morbidities were retrieved from nationwide medical registries. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using conditional logistic regression associating the Charlson comorbidity score (measured using both the original and an updated Charlson Comorbidity Index (CCI)) with incident breast cancer. Furthermore, we estimated associations between 202 morbidity categories and incident breast cancer, adjusting for multiple comparisons using empirical Bayes (EB) methods. Results The study included 46,324 cases and 463,240 population controls. Increasing CCI score, up to a score of six, was associated with slightly increased breast cancer risk. Among the Charlson diseases, preceding moderate to severe renal disease (OR = 1.25, 95% CI: 1.06, 1.48), any tumor (OR = 1.17, 95% CI: 1.10, 1.25), moderate to severe liver disease (OR = 1.86, 95% CI: 1.32, 2.62), and metastatic solid tumors (OR = 1.49, 95% CI: 1.17, 1.89), were most strongly associated with subsequent breast cancer. Preceding myocardial infarction (OR = 0.89, 95% CI: 0.81, 0.99), connective tissue disease (OR = 0.87, 95% CI: 0.80, 0.94), and ulcer disease (OR = 0.91, 95% CI: 0.83, 0.99) were most strongly inversely associated with subsequent breast cancer. A history of breast disorders was associated with breast cancer after EB adjustment. Anemias were inversely associated with breast cancer, but the association was near null after EB adjustment. Conclusions There was no substantial association between morbidity measured with the CCI and breast cancer risk.

Statins may affect non-cardiovascular endpoints, including cancer incidence and survival. These effects may depend on the solubility of the specific medicine. Our objective was to measure the association between post-diagnosis lipophilic and hydrophilic statin use and recurrence among non-metastatic breast cancer patients. We ascertained incident cases of stage I-III invasive breast cancer diagnosed in Denmark between 1996 and 2006 from the Danish Breast Cancer Cooperative Group registry, and linked these records to the Register of Medicinal Products (RMP), which automatically logs pharmacy transactions in Denmark. We determined statin prescriptions filled by cohort members by searching the RMP for appropriate ATC codes. Statins were classified by solubility (Table 1) and exposure status was updated yearly. Follow-up began upon completion of primary therapy and continued until the first of breast cancer recurrence, death from any cause, emigration from Denmark, or the end of 2006. Associations were estimated with time-dependent crude and multivariate Cox regression models. We enrolled 18,769 breast cancer patients, with a median follow-up of 6.2 years. Of the 3,282 women ever prescribed a statin after diagnosis, 2,518 were exclusively prescribed lipophilic statins and 210 were exclusively prescribed hydrophilic statins. Crude and multivariate models yielded similar estimates. Lipophilic (but not hydrophilic) statin use was associated with a reduced rate of breast cancer recurrence (compared with no statin use: multivariate HR for lipophilic statin use = 0.65, 95% CI: 0.55, 0.76; multivariate HR for hydrophilic statin use = 0.89, 95% CI: 0.61, 1.3). Associations were similar when estimated in the subset of women with no pre-diagnosis statin exposure. In this population-based prospective cohort study with complete information on prognostic and treatment variables, breast cancer patients who took lipophilic statins had a reduced rate of breast cancer recurrence. (a) Hazard ratios adjusted for age, menopausal status, tumor stage, ER status, adjuvant hormonal therapy, type of surgery, comorbidity, and co-prescription of aspirin. Estimates were similar in models further adjusted for chemotherapy, type of surgery, receipt of radiotherapy, and co-prescription of hormone replacement therapy, NSAIDs, anticoagulants and ACE inhibitors. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4678. doi:10.1158/1538-7445.AM2011-4678