Statin use and breast cancer: do we need more evidence and what should this be?

Statin use and risk of contralateral breast cancer: a nationwide cohort study

Background

Statins have demonstrated antineoplastic effects in breast cancer cell lines, particularly in oestrogen receptor (ER)-negative cell lines. However, epidemiological studies have not supported a preventive effect of statin use against breast cancer. Therefore, we examined the association between statin use and contralateral breast cancer (CBC) risk among women with breast cancer.

Methods

We identified 52,723 women with non-metastatic breast cancer during 1996–2012 from the Danish Breast Cancer Group database. We defined time-varying post-diagnosis statin use as minimum two prescriptions lagged by 1 year. Cox regression analyses were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for CBC associated with statin use.

Results

Statin use was associated with a lower CBC risk (HR = 0.88; 95% CI = 0.73–1.05). The inverse association was strongest for long-term use overall (HR = 0.64; 95% CI = 0.43–0.96), although the HR specifically for long-term consistent use and high-intensity use approached unity. Among ER-negative breast cancer patients, statin use was associated with a CBC risk reduction (HR = 0.67; 95% CI = 0.45–1.00).

Conclusions

We found some indication that statins reduce the risk of CBC. Further evaluations are needed to disentangle the equivocal results for long-term use and to establish if ER-negative breast cancer patients may benefit most from statin use.

Associations of Statin Use With Colorectal Cancer Recurrence and Mortality in a Danish Cohort

In earlier studies of the influence of hydroxymethylglutaryl-coenzyme A reductase inhibitors (also known as statins) on colorectal cancer prognosis, investigators reported a reduced rate of cancer-specific mortality. Studies of recurrence are few and small. Using data from Danish registries, we followed 21,152 patients diagnosed with stage I-III colorectal cancer from 2001 to 2011. We estimated the association between statin use in the preceding year and cancer recurrence, cancer-specific mortality, and all-cause mortality rates. We identified 5,036 recurrences, 7,084 deaths from any cause, and 4,066 deaths from colorectal cancer. After adjustment for potential confounders, statin use was not associated with recurrence (adjusted hazard ratio (aHR) = 1.01, 95% confidence interval (CI): 0.93, 1.09), but it was associated with death from colorectal cancer (aHR = 0.72, 95% CI: 0.65, 0.79) and death from any cause (aHR = 0.72, 95% CI: 0.67, 0.76). Statin use in the year preceding recurrence was associated with a reduced risk of cancer-specific mortality (aHR = 0.83, 95% CI: 0.74, 0.92) but also a reduced risk of death from any other cause (aHR = 0.78, 95% CI: 0.61, 1.00). Statin use was not associated with a reduced rate of colorectal cancer recurrence, but it was associated with a reduced rate of cancer-specific mortality, which suggests that there is no cancer-directed benefit; therefore, there is no basis to prescribe statins to colorectal cancer patients who do not have cardiovascular indications.

Statins and risk of breast cancer recurrence

Background

The primary end point of our study was to test whether the concurrent use of a statin is related to a lower risk of recurrence and increased relapse-free survival in patients with early breast cancer.

Materials and methods

We reviewed 610 female patients with stage I, II, or III breast cancer who had been surgically treated and who had subsequently received at least adjuvant chemotherapy in order to prevent recurrence.

Results

Among the 610 patients with breast cancer, 83 (13.6%) were receiving a statin on a chronic basis for other medical purposes. Overall, statin users displayed longer mean relapse-free survival (16.6 vs 10.2 years, P=0.028). After data had been adjusted for patient and disease characteristics, statin users maintained a lower risk of recurrence. This favorable outcome in statin users was particularly evident when we included only younger patients in the analysis (20 vs 10 years, P=0.006).

Conclusion

Statins may be linked to a favorable outcome in early breast cancer patients, especially in younger age-groups.

Statin use and breast cancer survival and risk: a systematic review and meta-analysis

The purpose of this study is to determine the associations between statin use and breast cancer survival and risk by performing a systematic review and meta-analysis. We searched PubMed, Embase and Web of Science up to August 2015 for identifying relevant prospective or case-control studies, or randomized clinical trials. Five prospective studies involving 60,911 patients reported the association between statin use and breast cancer mortality. Eleven prospective studies, 12 case-control studies and 9 randomized clinical trials involving 83,919 patients reported the association between statin use and breast cancer risk. After pooling estimates from all available studies, there was a significantly negative association between pre-diagnosis statin use and breast cancer mortality (for overall survival (OS): hazard ratio (HR) = 0.68, 95% confidence interval (CI) 0.54–0.84; for disease specific survival (DSS): HR = 0.72, 95% CI 0.53–0.99). There was also a significant inverse association between post-diagnosis statin use and breast cancer DSS (HR = 0.65, 95% CI 0.43–0.98), although the association with breast cancer OS did not reach statistical significance (HR = 0.71, 95% CI 0.48–1.07). Additionally, there was a non-linear relationship for the duration of post-diagnosis statin use with breast cancer specific mortality. On the other hand, with regards to the relationship between statin use and breast cancer risk, no significant association was detected. Our analyses suggest that although statin use may not influence breast cancer risk, the use of statin may be associated with decrease mortality of breast cancer patients. Further large-scale studies are warranted to validate our findings.

Prolonged use of human insulin increases breast cancer risk in Taiwanese women with type 2 diabetes

Background

Human insulin is commonly used to treat hyperglycemia in patients with diabetes, but its potential link with female breast cancer is under debate. This study investigated whether human insulin use might be associated with breast cancer risk in Taiwanese women with type 2 diabetes.

Methods

The reimbursement databases of all Taiwanese diabetic patients from 1996 to 2009 were retrieved from the National Health Insurance. An entry date was set at 1 January 2004 and a total of 482,033 women with type 2 diabetes were followed up for breast cancer incidence until the end of 2009. Incidences for ever-users, never-users and subgroups of human insulin exposure (using tertile cutoffs of time since starting insulin, cumulative dose and cumulative duration of insulin) were calculated and the adjusted hazard ratios were estimated by Cox regression. The potential risk modification by concomitant treatment with metformin, statin and angiotensin converting enzyme inhibitor/angiotensin receptor blocker (ACEI/ARB) was also evaluated.

Results

There were 59,798 ever-users and 422,235 never-users of human insulin, with respective numbers of incident breast cancer of 559 (0.93 %) and 4,711 (1.12 %), and respective incidence of 207.9 and 215.1 per 100,000 person-years. The overall adjusted hazard ratio (95 % confidence interval) did not show a significant association with insulin [1.033 (0.936-1.139)]. However, patients in the third tertiles of dose–response parameters might show a significantly higher risk of breast cancer while compared to never-users: 1.185 (1.026-1.368), 1.260 (1.096-1.450) and 1.257 (1.094-1.446) for ≥67 months for time since starting insulin, ≥39,000 units for cumulative dose of insulin, and ≥21.8 months for cumulative duration of insulin, respectively. Additional analyses suggested that the breast cancer risk associated with human insulin use might be beneficially modified by concomitant use of metformin, statin and ACEI/ARB.

Conclusions

This study discloses a significantly higher risk of breast cancer associated with prolonged use of human insulin. The increased risk of breast cancer associated with human insulin use may be modified by medications such as metformin, statin and ACEI/ARB.

Statins: do they have a potential role in cancer prevention and modifying cancer-related outcomes?

3-Hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (statins) are currently among the most commonly prescribed pharmaceutical agents worldwide. Apart from their well-established therapeutic value in cardiovascular disease, there is a long-standing debate on their potential association with cancer. To obtain and discuss the existing clinical evidence, an overview of meta-analysis articles addressing this issue was carried out. As of today, the accumulated evidence does not support the hypothesis that statins affect the risk of developing cancer, when they are taken at low doses for managing hypercholesterolaemia. However, current data cannot exclude an increased cancer risk in elderly patients associated with hydrophilic statin use, or decreases in the risks of certain cancers, such as gastric, oesophageal, liver, colorectal and advanced/aggressive prostate cancer. On the other hand, some recent observational studies have provided evidence that statins might be useful in modifying the prognosis of patients diagnosed with malignancy. Until a definitive benefit is demonstrated in randomized controlled trials, statins cannot be recommended either for cancer prevention or for modifying cancer-related outcomes. Further research is warranted to clarify the potential role(s) of statins in the prevention and treatment of cancer.

Combination of Pitavastatin and melatonin shows partial antineoplastic effects in a rat breast carcinoma model

Our previous results indicated significant tumor-suppressive effects of different statins in rat mammary carcinogenesis. The purpose of this experiment was to examine the chemopreventive effects of Pitavastatin alone and in combination with the pineal hormone melatonin in the model of N-methyl-N-nitrosourea-induced mammary carcinogenesis in female Sprague-Dawley rats. Pitavastatin was administered dietary (10mg/kg) and melatonin in an aqueous solution (20μg/ml). Chemoprevention began 7 days prior to carcinogen administration and subsequently continued for 15 weeks until autopsy. At autopsy, mammary tumors were removed and prepared for histopathological and immunohistochemical analysis. Compared to controls, Pitavastatin alone reduced average tumor volume by 58% and lengthened latency by 8 days; on the other hand, the drug increased tumor frequency by 23%. Combined administration of Pitavastatin with melatonin decreased tumor frequency by 23%, tumor volume by 44% and lengthened tumor latency by 5.5 days compared to control animals. The analysis of carcinoma cells showed significant increase in caspase-3 expression in both treated groups and a tendency of increased caspase-7 expression after Pitavastatin treatment alone. Significant expression decrease of Ki67 was found in carcinoma cells from both treated groups. Compared to control carcinoma cells, Pitavastatin alone increased VEGF expression by 41%, however melatonin totally reversed its undesirable effect. Pitavastatin combined with melatonin significantly increased femur compact bone thickness in animals. Pitavastatin alone decreased plasma triglycerides and total cholesterol levels, however it significantly increased levels of glucose. In summary, our results show a partial antineoplastic effect of Pitavastatin combined with melatonin in the rat mammary gland carcinoma model.