Effects of adjuvant aromatase inhibitor therapy on lipid profiles

Biomarkers predictive of a response to extended endocrine therapy in breast cancer: a systematic review and meta-analysis

PURPOSE

Extension of adjuvant endocrine therapy beyond five years confers only modest survival benefit in breast cancer patients and carries risk of toxicities. This systematic review investigates the role of biomarker tests in predicting the clinical response to an extension of endocrine therapy.

METHODS

We searched Ovid MEDLINE, Ovid Embase, Global Index Medicus, and the Cochrane Central Register of Controlled Trials using an iterative approach to identify full-text articles related to breast cancer, endocrine therapy, and biomarkers.

RESULTS

Of the 1,217 unique reports identified, five studies were deemed eligible. Four investigated the Breast Cancer Index (BCI) assay in three distinct study populations. These studies consistently showed that BCI score was predictive of response to extended endocrine therapy among 1,946 combined patients, who were predominately non-Hispanic white and postmenopausal.

CONCLUSIONS

Evidence in the setting of predictive tests for extended endocrine therapy is sparse. Most relevant studies investigated the use of BCI, but these study populations were largely restricted to a single age, race, and ethnicity group. Future studies should evaluate a variety of biomarkers in diverse populations. Without sufficient evidence, physicians and patients face a difficult decision in balancing the benefits and risks of endocrine therapy extension.

Development of cardiometabolic risk factors following endocrine therapy in women with breast cancer

PURPOSE

Studies comparing the effect of aromatase inhibitor (AI) and tamoxifen use on cardiovascular disease (CVD) risk factors in hormone receptor-positive breast cancer (BC) survivors report conflicting results. We examined associations of endocrine therapy use with incident diabetes, dyslipidemia, and hypertension.

METHODS

The Pathways Heart Study examines cancer treatment exposures with CVD-related outcomes in Kaiser Permanente Northern California members with BC. Electronic health records provided sociodemographic and health characteristics, BC treatment, and CVD risk factor data. Hazard ratios (HR) and 95% confidence intervals (CI) of incident diabetes, dyslipidemia, and hypertension in hormone receptor-positive BC survivors using AIs or tamoxifen compared with survivors not using endocrine therapy were estimated using Cox proportional hazards regression models adjusted for known confounders.

RESULTS

In 8985 BC survivors, mean baseline age and follow-up time was 63.3 and 7.8 years, respectively; 83.6% were postmenopausal. By treatment, 77.0% used AIs, 19.6% used tamoxifen, and 16.0% used neither. Postmenopausal women who used tamoxifen had an increased rate (HR 1.43, 95% CI 1.06-1.92) of developing hypertension relative to those who did not use endocrine therapy. Tamoxifen use was not associated with incident diabetes, dyslipidemia, or hypertension in premenopausal BC survivors. Postmenopausal AI users had higher hazard rates of developing diabetes (HR 1.37, 95% CI 1.05-1.80), dyslipidemia (HR 1.58, 95% CI 1.29-1.92), and hypertension (HR 1.50, 95% CI 1.24-1.82) compared with non-endocrine therapy users.

CONCLUSION

Hormone receptor-positive BC survivors treated with AIs may have higher rates of developing diabetes, dyslipidemia, and hypertension over an average 7.8 years post-diagnosis.

Development of cardiometabolic risk factors following endocrine therapy in women with breast cancer

PURPOSE

Studies comparing the effect of aromatase inhibitor (AI) and tamoxifen use on cardiovascular disease (CVD) risk factors in hormone-receptor positive breast cancer (BC) survivors report conflicting results. We examined associations of endocrine therapy use with incident diabetes, dyslipidemia, and hypertension.

METHODS

The Pathways Heart Study examines cancer treatment exposures with CVD-related outcomes in Kaiser Permanente Northern California members with BC. Electronic health records provided sociodemographic and health characteristics, BC treatment, and CVD risk factor data. Hazard ratios (HR) and 95% confidence intervals (CI) of incident diabetes, dyslipidemia, and hypertension in hormone-receptor positive BC survivors using AIs or tamoxifen compared with survivors not using endocrine therapy were estimated using Cox proportional hazards regression models adjusted for known confounders.

RESULTS

In 8,985 BC survivors, mean baseline age and follow-up time was 63.3 and 7.8 years, respectively; 83.6% were postmenopausal. By treatment, 77.0% used AIs, 19.6% used tamoxifen, and 16.0% used neither. Postmenopausal women who used tamoxifen had an increased rate (HR: 1.43, 95% CI: 1.06-1.92) of developing hypertension relative to those who did not use endocrine therapy. Tamoxifen use was not associated with incident diabetes, dyslipidemia, or hypertension in premenopausal BC survivors. Postmenopausal AI users had higher hazard rates of developing diabetes (HR: 1.37, 95% CI: 1.05-1.80), dyslipidemia (HR: 1.58, 95% CI: 1.29-1.92) and hypertension (HR: 1.50, 95% CI: 1.24-1.82) compared with non-endocrine therapy users.

CONCLUSION

Hormone-receptor positive BC survivors treated with AIs may have higher rates of developing diabetes, dyslipidemia, and hypertension over an average 7.8 years post-diagnosis.

Risk of Cardiovascular Events and Lipid Profile Change in Patients with Breast Cancer Taking Aromatase Inhibitor: A Systematic Review and Meta-Analysis

Cardiovascular disease (CVD) is one of the most common comorbidities in breast cancer survivors. Recently, the target population and treatment period for aromatase inhibitor (AI) treatment in breast cancer patients has been expanding. However, information on adverse CVD events from the long-term use of AI is still lacking. The aim of this study was to investigate the CVD side effects of AI treatment and to evaluate the changes in lipid profile during AI treatment. A systematic search of PubMed (Medline), EMBASE, and Cochrane Library databases reporting on cardiovascular outcomes or lipid profiles change in adult female breast cancer patients (>19 years old) with AI was performed. The pooled analysis of 25 studies showed that the prevalence rate of any type of cardiovascular disease was 6.08 per 100 persons (95% CI 2.91-10.31). Angina was the most common type of heart-related cardiovascular event accounting for 3.85 per 100 persons, followed by any type of stroke (3.34) and venous thromboembolism (2.95). Ischemic stroke (OR 1.39, 95% CI 1.07-1.81) and myocardial infarction (OR 1.30, 95% CI 0.88-1.93) were more common in AI compared with tamoxifen, whereas the prevalence of venous thromboembolism (OR 0.61, 95% CI 0.37-1) was significantly lower in the AI group. In addition, treatment with AI for 6-12 months showed a decrease in HDL-cholesterol and an increase in LDL-cholesterol and total cholesterol. Various CVDs can occur when using AI, and in particular, the risk of MI and ischemic stroke increases in comparison with the adverse effect of tamoxifen. The occurrence of CVD might be related to the deterioration of the lipid profile after AI treatment. Therefore, a customized individualization strategy considering each patient's CV risk factors is needed during AI treatment.

Randomized Multicenter Placebo-Controlled Trial of Omega-3 Fatty Acids for the Control of Aromatase Inhibitor-Induced Musculoskeletal Pain: SWOG S0927

PURPOSE

Musculoskeletal symptoms are the most common adverse effects of aromatase inhibitors (AIs) and can result in decreased quality of life and discontinuation of therapy. Omega-3 fatty acids (O3-FAs) can be effective in decreasing arthralgia resulting from rheumatologic conditions and reducing serum triglycerides.

PATIENTS AND METHODS

Women with early-stage breast cancer receiving an AI who had a worst joint pain/stiffness score ≥ 5 of 10 using the Brief Pain Inventory-Short Form (BPI-SF) were randomly assigned to receive either O3-FAs 3.3 g or placebo (soybean/corn oil) daily for 24 weeks. Clinically significant change was defined as ≥ 2-point drop from baseline. Patients also completed quality-of-life (Functional Assessment of Cancer Therapy-Endocrine Symptoms) and additional pain/stiffness assessments at baseline and weeks 6, 12, and 24. Serial fasting blood was collected for lipid analysis.

RESULTS

Among 262 patients registered, 249 were evaluable, with 122 women in the O3-FA arm and 127 in the placebo arm. Compared with baseline, the mean observed BPI-SF score decreased by 1.74 points at 12 weeks and 2.22 points at 24 weeks with O3-FAs and by 1.49 and 1.81 points, respectively, with placebo. In a linear regression adjusting for the baseline score, osteoarthritis, and taxane use, adjusted 12-week BPI-SF scores did not differ by arm (P = .58). Triglyceride levels decreased in patients receiving O3-FA treatment and remained the same for those receiving placebo (P = .01). No between-group differences were seen for HDL, LDL, or C-reactive protein.

CONCLUSION

We found a substantial (> 50%) and sustained improvement in AI arthralgia for both O3-FAs and placebo but found no meaningful difference between the groups.

Malignancy-associated dyslipidemia

Cholesterol and triglycerides, important lipid constituents of cell, are essential to carry out several vital physiological functions. Lipids might be associated with cancers because they play a key role in the maintenance of cell integrity. The pathway for cholesterol synthesis may also produce various tumorigenic compounds and cholesterol serves as a precursor for the synthesis of many sex hormones linked to increased risk of various cancers. In some malignant diseases, blood cholesterol undergoes early and significant changes. The mechanism for the link between cancer and cholesterol remains controversial. The dates from studies are confusing because both hypolipidemia and hypercholesterolemia might be connected with malignancy. Not only cancers but also antineoplastic therapies have an influence on lipid profile. There are also dates suggesting that antihyperlipemic drugs might nfluenced malignancy.

Aromatase inhibitors versus tamoxifen as adjuvant hormonal therapy for oestrogen sensitive early breast cancer in post-menopausal women: meta-analyses of monotherapy, sequenced therapy and extended therapy

Adjuvant tamoxifen reduces relapses and prolongs survival in patients with oestrogen sensitive breast cancer. Development of resistance is however common. Tamoxifen can be given for a maximum of five years; although the risk of recurrences remains high after this period. This review examines nine randomised controlled trials including 28,632 women, which studied aromatase inhibitors (AIs) as an alternative to tamoxifen in three treatment settings: monotherapy (instead of tamoxifen), sequenced therapy (tamoxifen is switched to an AI) and extended therapy (following adjuvant tamoxifen). Disease free survival was significantly improved for monotherapy (HR 0.89, [95% CI 0.83-0.96] p = 0.002) and sequenced therapy (HR 0.72, [0.63-0.83] p < 0.00001). There was no difference in overall survival for monotherapy (HR 0.94, [0.82-1.08] p = 0.39) or extended therapy (HR 0.86 [0.79-1.16] p = 0.67). Importantly, overall survival was prolonged for patients who switched from tamoxifen to AI therapy (HR 0.78 95%CI 0.68-0.91, p = 0.001).

Long-term efficacy and safety of letrozole for the adjuvant treatment of early breast cancer in postmenopausal women: a review

Aromatase inhibitors (AIs) are becoming more widely used than tamoxifen as adjuvant hormonal therapy for postmenopausal women (PMW) with early breast cancer (EBC). It is clear that these drugs offer important efficacy benefits over tamoxifen and differ from tamoxifen in their safety profile. The accepted strategies for adjuvant AI therapy include initial adjuvant treatment following surgery, switching and/or sequencing from prior tamoxifen, and extended adjuvant therapy following the full 5 years of tamoxifen treatment. Among the available AIs, letrozole has been evaluated in large, well-controlled, double-blind clinical trials in the initial adjuvant, extended adjuvant, and more recently, the sequential adjuvant settings. Letrozole is the most potent of the AIs and provides near complete suppression of plasma estrogens in PMW. Letrozole also significantly reduces the occurrence of early distant metastases, the most lethal type of recurrence event, which can lead to improved survival. Clinical comparisons of letrozole with both tamoxifen and placebo have also provided important long-term safety data on the use of AIs as adjuvant therapy in PMW with EBC. The weight of clinical evidence indicates that letrozole is a safe and effective option for adjuvant hormonal therapy across all three AI treatment settings.

Effects of hormonal treatment on lipids in patients with cancer

Patients with malignant disease may need hormonal therapy as primary or adjuvant treatment or for palliation. Oestrogens usually decrease serum levels of total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C), increase high density lipoprotein cholesterol (HDL-C) concentration, but induce an elevation in serum triglyceride (TG) levels. Progestogens in the short-term decrease TC, LDL-C and HDL-C concentrations, and increase TG levels. In long-term treatment, progestogens usually have a small impact on lipid profile. Tamoxifen induces a decrease in TC and LDL-C levels, an increase in TG concentration, whereas either an increase, decrease or no change has been reported for HDL-C levels. Aromatase inhibitors induce an elevation, reduction or no change in lipid variables. These results depend mainly on the trial design, i.e. whether patients received prior treatment with tamoxifen or not and the duration of therapy. Gonadorelin analogues increase all lipid variables, but LDL-C alterations are usually non-significant. Anti-androgens usually decrease TC, LDL-C and HDL-C levels, whereas TG alterations vary. Information regarding the effects on lipid profile of somatostatin analogues is available almost exclusively in patients with acromegaly. In these patients somatostatin analogues usually induce no change or a decrease in TC and LDL-C levels, whereas they increase HDL-C and decrease TG serum concentrations. Oncologists should consider the lifestyle changes, and if needed hypolipidemic treatment, used to lower cardiovascular risk in non-cancer patients. Tamoxifen may rarely cause serious TG-related side effects, like acute pancreatitis.