Incident Type 2 Diabetes Risk of Selective Estrogen Receptor Modulators in Female Patients with Breast Cancer

Risk of type 2 diabetes after breast cancer treatment: a population-based cohort study in Denmark

PURPOSE

Data on type 2 diabetes (T2D) risk after breast cancer (BC) could guide preventive strategies. Yet, studies had limitations regarding sample size, follow-up, and contemporary treatments. We evaluated the risk of T2D after BC overall, by cancer treatment, and compared with a matched cohort of cancer-free women.

METHODS

We assembled a population-based cohort of early-stage BC patients aged 30 years or more diagnosed during 1996-2021 in Denmark. We created a comparison cohort of 5 cancer- and T2D-free women for each BC patient, matched 6 months after BC diagnosis date on age and region. We followed both cohorts until T2D diagnosis, emigration, death, or December 31, 2022. We computed 5-year cumulative incidences and used Cox models to calculate time-varying adjusted hazard ratios (aHR) of T2D.

RESULTS

Among 74 526 BC survivors and 372 630 matched cancer-free women, 5-year cumulative incidences of T2D were 3.8% (95% confidence interval [CI] = 3.7 to 3.9) and 3.3% (95% CI = 3.3 to 3.4), respectively. The aHR of T2D was elevated but attenuated over follow-up (aHR5-years = 1.20, 95% CI = 1.15 to 1.25, and aHR15-years = 1.09, 95% CI = 1.05 to 1.12). Adjuvant endocrine therapy (aHR = 1.14; 95% CI = 1.10 to 1.19), aromatase inhibitors (aHR = 1.25; 95% CI = 1.18 to 1.32), and less so tamoxifen (aHR = 1.05; 95% CI = 0.99 to 1.11), were associated with elevated risk of T2D in women with BC vs cancer-free women. Among BC patients, chemotherapy (aHR = 1.10, 95% CI = 1.03 to 1.17) and radiation therapy (right-sided aHR = 1.18, 95% CI = 1.09 to 1.27 and left-sided aHR = 1.24, 95CI = 1.15 to 1.33) were associated with increased T2D risk.

CONCLUSION

BC was associated with excess risk of T2D, although of lower magnitude than previously reported. The excess risk was temporary and related to BC treatment but could also be influenced by obesity and heightened T2D diagnostic activity.

Adherence, clinical benefits, and adverse effects of endocrine therapies among women with nonmetastatic breast cancer in developing countries: A systematic review and meta-analysis

BACKGROUND

Despite significant advances in breast cancer control and survival with endocrine therapies (ETs), treatment utilization and outcomes in developing countries have not been adequately explored. This review evaluated ET adherence, potential benefits, and harms in populations across developing countries.

METHODS

A literature search was conducted through August 2023 in five databases: PubMed, Cochrane Library, Web of Science, Global Health, and WHO Global Index Medicus. Retrieved records were screened to identify observational research presenting at least one outcome in women with nonmetastatic breast cancer in developing countries who received ET (tamoxifen or aromatase inhibitors). A random effects model was used to compute the rates of adherence, discontinuation, adverse events (AEs), disease progression, and death.

RESULTS

A total of 104 studies met the inclusion criteria. Risk of bias was low in most studies, and a large portion of the patients involved Asians. The overall heterogeneity between studies was partially attributed to variations in study design or outcome measurement method. Results showed a pooled adherence rate of 75% (95% confidence interval [CI], 67%-81%) and a discontinuation rate of 16% (95% CI, 10%-25%). Treatment side effects and young age consistently emerged as significant predictors of nonadherence. A wide range of AEs was identified in our analysis. The estimated average rates of cancer recurrence and mortality at 5-years were 16% and 8%, respectively.

CONCLUSIONS

The findings of this study underscore suboptimal ET use in developing countries and provide comprehensive insights into treatment experiences in the real-world setting. Targeted strategies are warranted to enhance adherence and subsequently optimize treatment benefits.

Deciphering the role of classical oestrogen receptor in insulin resistance and type 2 diabetes mellitus: From molecular mechanism to clinical evidence

The biological actions of oestrogen are mediated by the oestrogen receptor α or β (ERα or ERβ), which are members of a broad nuclear receptor superfamily. Numerous in vivo and in vitro studies have demonstrated that loss of circulating oestrogen modulated by classical ERα and ERβ led to rapid changes in pancreatic β-cell and islet function, GLUT4 expression, insulin sensitivity and glucose tolerance, dysfunctional lipid homeostasis, oxidative stress, and inflammatory cascades. Remarkably, 17β-oestradiol (E2) can completely reverse these effects. This review evaluates the current understanding of the protective role of classical ER in critical pathways and molecular mechanisms associated with insulin resistance and type 2 diabetes mellitus (T2DM). It also examines the effectiveness of menopausal hormone therapy (MHT) in reducing the risk of developing T2DM in menopausal women. Clinical trials have shown the protective effects of MHT on glucose metabolism, which may be useful to treat T2DM in perimenopausal women. However, there are concerns about E2's potential side effects of obesity and hyperlipidaemia in menopausal women. Further studies are warranted to gain understanding and find other oestrogen alternatives for treatment of insulin resistance and T2DM in postmenopausal women.

In silico screening of potential agonists of a glucagon-like peptide-1 receptor among female sex hormone derivatives

Glucagon-like peptide-1 (GLP-1) is an intestinal hormone that exerts its pleiotropic effects through a specific GLP-1 receptor (GLP-1R). The hormone-receptor complex might regulate glucose-dependent insulin secretion, and energy homeostasis; moreover, it could decrease inflammation and provide cardio- and neuroprotection. Additionally, the beneficial influence of GLP-1 on obesity in women might lead to improvement of their ovarian function. The links between metabolism and reproduction are tightly connected, and it is not surprising that different estrogen derivatives, estrogen-receptor modulator (SERM) and progestins used for gonadal and oncological disorders might influence carbohydrate and lipid metabolism. However, their possible influence on the GLP-1R has not been studied. The docking scores and top-ranked poses of raloxifene were much higher than those observed for other investigated SERMs and estradiol per se. Among different studied progestins, drospirenone showed slightly higher affinity to GLP-1R. Herein, the same data set of the drugs is evaluated by molecular dynamics (MD) simulations and compared with the obtained docking result. Notably, it is demonstrated that the used docking protocol and the applied MD calculations ranked the same ligand (raloxifene) as the best one. In the present study, raloxifene might exert an allosteric influence on GLP-1R signaling, which might contribute to potential beneficial effects on metabolism and weight regulation. However, further experimental and clinical studies are needed to reveal if the GLP-1R modulation has a real biological impact.

Diabetes mellitus in breast cancer survivors: metabolic effects of endocrine therapy

Breast cancer is the most common invasive malignancy in the world, with millions of survivors living today. Type 2 diabetes mellitus (T2DM) is also a globally prevalent disease that is a widely studied risk factor for breast cancer. Most breast tumours express the oestrogen receptor and are treated with systemic therapies designed to disrupt oestrogen-dependent signalling. Since the advent of targeted endocrine therapy six decades ago, the mortality from breast cancer has steadily declined; however, during the past decade, an elevated risk of T2DM after breast cancer treatment has been reported, particularly for those who received endocrine therapy. In this Review, we highlight key events in the history of endocrine therapies, beginning with the development of tamoxifen. We also summarize the sequence of reported adverse metabolic effects, which include dyslipidaemia, hepatic steatosis and impaired glucose tolerance. We discuss the limitations of determining a causal role for breast cancer treatments in T2DM development from epidemiological data and describe informative preclinical studies that suggest complex mechanisms through which endocrine therapy might drive T2DM risk and progression. We also reinforce the life-saving benefits of endocrine therapy and highlight the need for better predictive biomarkers of T2DM risk and preventive strategies for the growing population of breast cancer survivors.

Breast cancer and incidence of type 2 diabetes mellitus: a systematic review and meta-analysis

PURPOSE

Breast cancer and its treatments may increase the risk of type 2 diabetes (T2D). We conducted a systematic review and meta-analysis to investigate the association between breast cancer and the incidence of T2D overall, and according to breast cancer treatments.

METHODS

We searched PubMed, Embase and references of relevant papers for studies on breast cancer, breast cancer treatment, and subsequent T2D risk. Using random-effects models, we calculated effect estimates and associated 95% confidence intervals of the association between breast cancer, adjuvant breast cancer treatments (i.e., endocrine therapy (tamoxifen, aromatase inhibitors, and combined) and chemotherapy), and subsequent T2D. We used funnel plots to assess publication bias.

RESULTS

Among 15 eligible studies, 10 reported on T2D risk after breast cancer, chemotherapy, or endocrine therapy; five studies investigated more than one association. Compared with patients without breast cancer, those with breast cancer and those who received any endocrine therapy had elevated risk of incident T2D (EE = 1.23, 95% CI = 1.13-1.33 and EE = 1.23, 95% CI = 1.16-1.32, respectively). Among breast cancer patients only, the risk of T2D was higher for those who received tamoxifen compared with those who did not receive tamoxifen (EE = 1.28, 95% CI = 1.18-1.38). Due to few studies, analyses investigating T2D risk after treatment with aromatase inhibitors or chemotherapy were inconclusive.

CONCLUSION

Our findings suggest an elevated risk of T2D in breast cancer survivors, particularly after tamoxifen therapy. Further research is needed to determine the impact of aromatase inhibitors, and chemotherapy on the incidence of T2D after breast cancer.

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.

Effects of Endocrine Therapy on Cardiovascular Diseases and Type 2 Diabetes Among Breast Cancer Survivors: The National Health Insurance Service Database of Korea

Background Although endocrine therapy is an effective treatment for breast cancer, its antiestrogen effects are associated with increased risks of cardiovascular diseases and type 2 diabetes. This study aimed to investigate the association between endocrine therapy and the risk of cardiovascular diseases and type 2 diabetes among breast cancer survivors in Korea, in consideration of various age groups. Methods and Results In the National Health Insurance Service database of Korea, a total of 133 171 patients with breast cancer aged ≥20 years were included in the current study. Endocrine therapy was treated as time-varying exposure, and patients were categorized as nonusers, selective estrogen receptor modulator users, aromatase inhibitor users, and both users. Time-dependent Cox regression models were used to estimate hazard ratios (HRs) and 95% CIs. Age at diagnosis, socioeconomic status, histological type, other treatments, and comorbidities were adjusted in the model. Compared with nonusers, selective estrogen receptor modulator users were associated with higher risks of stroke (HR, 1.20 [95% CI, 1.04-1.40]) and venous thromboembolism (HR, 1.47 [95% CI, 1.13-1.90]), whereas aromatase inhibitor users were associated with a higher risk of coronary heart disease (HR, 1.22 [95% CI, 1.06-1.41]). The risk of type 2 diabetes was associated with selective estrogen receptor modulator users (HR, 1.13 [95% CI, 1.05-1.21]), aromatase inhibitor users (HR, 1.14 [95% CI, 1.05-1.23]), and both users (HR, 1.24 [95% CI, 1.10-1.39]). In particular, the risk of a composite of cardiovascular diseases was higher in younger or premenopausal patients. Conclusions In breast cancer survivors in Korea, endocrine therapy is associated with a higher risk of cardiovascular diseases and type 2 diabetes. Monitoring of cancer comorbidities after endocrine therapy is needed in younger and older patients.

Bacterial lectin BambL acts as a B cell superantigen

B cell superantigens crosslink conserved domains of B cell receptors (BCRs) and cause dysregulated, polyclonal B cell activation irrespective of normal BCR-antigen complementarity. The cells typically succumb to activation-induced cell death, which can impede the adaptive immune response and favor infection. In the present study, we demonstrate that the fucose-binding lectin of Burkholderia ambifaria, BambL, bears functional resemblance to B cell superantigens. By engaging surface glycans, the bacterial lectin activated human peripheral blood B cells, which manifested in the surface expression of CD69, CD54 and CD86 but became increasingly cytotoxic at higher concentrations. The effects were sensitive to BCR pathway inhibitors and excess fucose, which corroborates a glycan-driven mode of action. Interactome analyses in a model cell line suggest BambL binds directly to glycans of the BCR and regulatory coreceptors. In vitro, BambL triggered BCR signaling and induced CD19 internalization and degradation. Owing to the lectin's six binding sites, we propose a BCR activation model in which BambL functions as a clustering hub for receptor glycans, modulates normal BCR regulation, and induces cell death through exhaustive activation.