Combined effect of obesity and diabetes on early breast cancer outcome: a prospective observational study

The effect of BMI on survival outcome of breast cancer patients: a systematic review and meta-analysis

OBJECTIVE

The main goal of the present research is to explore the potential link of body mass index (BMI) with different survival metrics in breast cancer patients. Our aim is to offer the latest and most thorough meta-analysis, assessing the strength and reliability of the connection that BMI has with prognostic indicators in this disease.

PATIENTS AND METHODS

As of January 2024, we conducted a systematic literature search across PubMed, Embase, Web of Science, and the Cochrane Library databases. Our search aimed to identify studies examining BMI as an exposure factor, with breast cancer patients constituting the study population, and utilizing adjusted hazard ratio (HR) as the data type of interest.

RESULTS

The evidence synthesis incorporated a total of 61 eligible articles involving 201,006 patients. Being underweight posed a risk factor for overall survival (OS) in breast cancer patients compared to normal weight (HR 1.15, 95% CI 0.98-1.35; P = 0.08). Overweight or obesity, in comparison to normal weight, was a risk factor for OS (HR 1.18, 95% CI 1.14-1.23; P < 0.00001), disease-free survival (DFS) (HR 1.11, 95% CI 1.08-1.13; P < 0.00001), relapse-free survival (RFS) (HR 1.14, 95% CI 1.06-1.22; P = 0.03), and breast cancer-specific survival (BCSS) (HR 1.18, 95% CI 1.11-1.26; P < 0.00001), but not for progression-free survival (PFS) (HR 0.91, 95% CI 0.76-1.10; P = 0.33). Notably, in subgroup analyses, overweight patients achieved prolonged PFS (HR 0.80, 95% CI 0.64-0.99; P = 0.04), and compared to the obese population, the overweight cohort exhibited a significant difference in OS (HR 1.11, 95% CI 1.05-1.16; P < 0.00001) and DFS (HR 1.06, 95% CI 1.03-1.10; P = 0.0004), with a considerably stronger association. Furthermore, compared to HER- patients, HER + patients exhibited a greater predictive value for OS (HR 1.23, 95% CI 1.10-1.37; P = 0.0004), RFS (HR 1.30, 95% CI 1.03-1.64; P < 0.00001), and DFS (HR 1.10, 95% CI 1.03-1.17; P = 0.003).

CONCLUSIONS

The results of our meta-analysis reveal a notable association between BMI and various survival measures in breast cancer prognosis. These findings provide a solid basis for predicting breast cancer outcomes and implementing more effective therapeutic approaches.

Association of Overweight and Inflammatory Indicators with Breast Cancer: A Cross-Sectional Study in Chinese Women

Objective

This cross-sectional study aimed to explore the association of overweight and inflammatory indicators with breast cancer risk in Chinese patients.

Methods

Weight, height, and peripheral blood inflammatory indicators, including white blood cell count (WBC), neutrophil count (NE), lymphocyte count (LY), platelet count (PLT) and the concentration of hypersensitivity C-reactive protein (hsCRP), were collected in 383 patients with benign breast lumps (non-cancer) and 358 patients with malignant breast tumors (cancer) at the First Affiliated Hospital of Soochow University, China, from March 2018 to July 2020. Body mass index (BMI), neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR) and systemic immune-inflammation index (SII) were determined according to the ratio equation. The correlations among overweight, inflammatory indicators, and the proportion of non-cancer or cancer cases were analyzed.

Results

BMI is associated with an increased breast cancer risk. Compared with non-cancer patients, the average WBC count, NE count, NLR, and level of hsCRP were significantly higher in cancer patients. The level of hsCRP was closely associated with the size of malignant breast tumors.

Conclusion

We conclude that overweight and high levels of hsCRP may serve as putative risk factors for malignant breast tumors in Chinese women.

Central obesity, body mass index, metabolic syndrome and mortality in Mediterranean breast cancer patients

Obesity and metabolic disorders have been associated with poor outcomes in non-Mediterranean breast cancer (BC) patients. The purpose of this study was to investigate the prognostic potential of anthropometric variables in patients with early BC living in Southern Mediterranean region of Italy. We enrolled 955 consecutive early BC patients treated in hospitals in Naples between 2009 and 2013 (median follow-up 11.8-year ending 15/09/2022). Body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR) and metabolic syndrome (MetS) were collected. All-cause and BC-specific mortality were calculated. At the last day of contact 208 (22%) patients had died, 131 (14%) from BC. High WC (≥ 88 cm) or WHR (> 0.85) and the MetS were significantly associated with moderately increased risk of all-cause mortality (HR=1.39, 1.62, 1.61, respectively). A significant increased risk of BC-specific mortality was found in obese patients, in those with high WC, high WHR and those with MetS (HR=1.72, 1.71, 1.80, 1.81, respectively). Central obesity significantly increased total and BC-specific mortality particularly in pre-menopausal women and in luminal subtypes, while in post-menopause MetS was a stronger risk factor. Obesity and MetS may impair the effectiveness of BC therapies hence active lifestyle interventions are encouraged.

Postdiagnosis body fatness, weight change and breast cancer prognosis: Global Cancer Update Program (CUP global) systematic literature review and meta-analysis

Previous evidence on postdiagnosis body fatness and mortality after breast cancer was graded as limited-suggestive. To evaluate the evidence on body mass index (BMI), waist circumference, waist-hip-ratio and weight change in relation to breast cancer prognosis, an updated systematic review was conducted. PubMed and Embase were searched for relevant studies published up to 31 October, 2021. Random-effects meta-analyses were conducted to estimate summary relative risks (RRs). The evidence was judged by an independent Expert Panel using pre-defined grading criteria. One randomized controlled trial and 225 observational studies were reviewed (220 publications). There was strong evidence (likelihood of causality: probable) that higher postdiagnosis BMI was associated with increased all-cause mortality (64 studies, 32 507 deaths), breast cancer-specific mortality (39 studies, 14 106 deaths) and second primary breast cancer (11 studies, 5248 events). The respective summary RRs and 95% confidence intervals per 5 kg/m2 BMI were 1.07 (1.05-1.10), 1.10 (1.06-1.14) and 1.14 (1.04-1.26), with high between-study heterogeneity (I2  = 56%, 60%, 66%), but generally consistent positive associations. Positive associations were also observed for waist circumference, waist-hip-ratio and all-cause and breast cancer-specific mortality. There was limited-suggestive evidence that postdiagnosis BMI was associated with higher risk of recurrence, nonbreast cancer deaths and cardiovascular deaths. The evidence for postdiagnosis (unexplained) weight or BMI change and all outcomes was graded as limited-no conclusion. The RCT showed potential beneficial effect of intentional weight loss on disease-free-survival, but more intervention trials and well-designed observational studies in diverse populations are needed to elucidate the impact of body composition and their changes on breast cancer outcomes.

The AGEs/RAGE Transduction Signaling Prompts IL-8/CXCR1/2-Mediated Interaction between Cancer-Associated Fibroblasts (CAFs) and Breast Cancer Cells

Advanced glycation end products (AGEs) and the cognate receptor, named RAGE, are involved in metabolic disorders characterized by hyperglycemia, type 2 diabetes mellitus (T2DM) and obesity. Moreover, the AGEs/RAGE transduction pathway prompts a dysfunctional interaction between breast cancer cells and tumor stroma toward the acquisition of malignant features. However, the action of the AGEs/RAGE axis in the main players of the tumor microenvironment, named breast cancer-associated fibroblasts (CAFs), remains to be fully explored. In the present study, by chemokine array, we first assessed that interleukin-8 (IL-8) is the most up-regulated pro-inflammatory chemokine upon AGEs/RAGE activation in primary CAFs, obtained from breast tumors. Thereafter, we ascertained that the AGEs/RAGE signaling promotes a network cascade in CAFs, leading to the c-Fos-dependent regulation of IL-8. Next, using a conditioned medium from AGEs-exposed CAFs, we determined that IL-8/CXCR1/2 paracrine activation induces the acquisition of migratory and invasive features in MDA-MB-231 breast cancer cells. Altogether, our data provide new insights on the involvement of IL-8 in the AGEs/RAGE transduction pathway among the intricate connections linking breast cancer cells to the surrounding stroma. Hence, our findings may pave the way for further investigations to define the role of IL-8 as useful target for the better management of breast cancer patients exhibiting metabolic disorders.

Diabetes and Cancer - optimising glycaemic control

Diabetes and cancer are both common and increasingly prevalent conditions, but emerging epidemiological evidence confirms that the risk of developing a number of common cancers is increased in those with type 2 diabetes. The risk of cancer in type 1 diabetes is less clearly defined, and therefore this review will focus on type 2 diabetes. Emerging evidence also supports an influence of diabetes on outcomes of cancer treatment. However, this relationship is bi-directional, with cancer and its treatment impacting on glucose control, whilst there is also emerging evidence that diabetes care can deteriorate after a cancer diagnosis (summarised in Figure 1). Despite these clear links there is a lack of evidence to guide clinicians in how to manage patients with diabetes during their cancer treatment. Although recent UK guidelines have started to address this, with the development of guidance for the management of hyperglycaemia in cancer, there is a clear need for wider guidance on the management of multi-morbidity during cancer, including diabetes and obesity, to incorporate nutritional management We have therefore undertaken a narrative review of the evidence of links between type 2 diabetes and cancer incidence and outcomes, and discuss the challenges to diabetes care during cancer treatment. This article is protected by copyright. All rights reserved.

Association of Obesity and Luminal Subtypes in Prognosis and Adjuvant Endocrine Treatment Effectiveness Prediction in Chinese Breast Cancer Patients

Purpose

To evaluate the influence of obesity on clinicopathological characteristics of breast cancer; to explore the effect of obesity on the prognosis and performance of endocrine therapy in breast cancer patients.

Methods

Patients with luminal/HER2-negative early breast cancer were included and categorized into the non-obese (BMI<28kg/m²) and obese (BMI≥28kg/m²) groups according to body mass index (BMI). Clinicopathological characteristics and treatment modalities were compared between groups. Interaction of adjuvant endocrine therapy with obesity was analyzed.

Results

A total of 2,875 patients were included: 2,598 non-obese and 277 obese. A higher rate of patients with comorbidities (OR: 2.83, 95%CI 2.13-3.74, P<0.001) or PR-positive tumor (OR: 1.63, 95%CI 1.03-2.58, P=0.037) were identified in the obese group. Obesity was not associated with disease recurrence (P=0.839) or overall survival (P=0.140) in the whole population. Subgroup analysis did show an association with worse relapse-free survival (RFS, HR 3.48, 95%CI 1.31-9.22, P=0.012) and overall survival (OS, HR 4.67, 95%CI 1.28-16.95, P=0.019) in luminal A breast cancer. These results could not be reproduced in the luminal B subtype with a RFS (HR 0.78, 95%CI 0.41-1.49, P=0.454) or OS (HR 1.17, 95%CI 0.50-2.74, P=0.727). Furthermore, obesity did not impact endocrine therapy effectiveness in Tamoxifen or the aromatase inhibitor group (RFS: interact P=0.381; OS: interact P=0.888).

Conclusions

The impact of obesity on prognosis interacted with luminal subtype status in Chinese breast cancer patients which was not related with endocrine treatment modality.

Obesity and endocrine therapy resistance in breast cancer: Mechanistic insights and perspectives

The incidence of obesity, a recognized risk factor for various metabolic and chronic diseases, including numerous types of cancers, has risen dramatically over the recent decades worldwide. To date, convincing research in this area has painted a complex picture about the adverse impact of high body adiposity on breast cancer onset and progression. However, an emerging but overlooked issue of clinical significance is the limited efficacy of the conventional endocrine therapies with selective estrogen receptor modulators (SERMs) or degraders (SERDs) and aromatase inhibitors (AIs) in patients affected by breast cancer and obesity. The mechanisms behind the interplay between obesity and endocrine therapy resistance are likely to be multifactorial. Therefore, what have we actually learned during these years and which are the main challenges in the field? In this review, we will critically discuss the epidemiological evidence linking obesity to endocrine therapeutic responses and we will outline the molecular players involved in this harmful connection. Given the escalating global epidemic of obesity, advances in understanding this critical node will offer new precision medicine-based therapeutic interventions and more appropriate dosing schedule for treating patients affected by obesity and with breast tumors resistant to endocrine therapies.

Body mass index and type 2 diabetes and breast cancer survival: a Mendelian randomization study

The causal relationship between body mass index (BMI) and type 2 diabetes (T2D) and breast cancer prognosis is still ambiguous. The aim of this study was to investigate the prognostic effect of BMI and T2D on breast cancer disease-free survival (DFS) among Asian individuals. In this two-sample Mendelian randomization (MR) study, the instrumental variables (IVs) were identified using a genome-wide association study (GWAS) among 24,000 participants in the Taiwan Biobank. Importantly, the validity of these IVs was confirmed with a previous large-scale GWAS (Biobank Japan Project, BBJ). In this study, we found that a genetic predisposition toward higher BMI (as indicated by BMI IVs, F = 86.88) was associated with poor breast cancer DFS (hazard ratio [HR] = 6.11; P < 0.001). Furthermore, higher level of genetically predicted T2D (as indicated by T2D IVs) was associated with an increased risk of recurrence of and mortality from breast cancer (HR = 1.43; P < 0.001). Sensitivity analyses, including the weighted-median approach, MR-Egger regression, Radial regression and Mendelian randomization pleiotropy residual sum and outlier (MR-PRESSO) supported the consistency of our findings. Finally, the causal relationship between BMI and poor breast cancer prognosis was confirmed in a prospective cohort study. Our MR analyses demonstrated the causal relationship between the genetic prediction of elevated BMI and a greater risk of T2D with poor breast cancer prognosis. BMI and T2D have important clinical implications and may be used as prognostic indicators of breast cancer.

Association of Obesity With Survival Outcomes in Patients With Cancer: A Systematic Review and Meta-analysis

Importance

Obesity, defined as a body mass index (BMI) greater than 30, is associated with a significant increase in the risk of many cancers and in overall mortality. However, various studies have suggested that patients with cancer and no obesity (ie, BMI 20-25) have worse outcomes than patients with obesity.

Objective

To assess the association between obesity and outcomes after a diagnosis of cancer.

Data Sources

PubMed, the Cochrane Library, and EMBASE were searched from inception to January 2020.

Study Selection

Studies reporting prognosis of patients with obesity using standard BMI categories and cancer were included. Studies that used nonstandard BMI categories, that were limited to children, or that were limited to patients with hematological malignant neoplasms were excluded. Screening was performed independently by multiple reviewers. Among 1892 retrieved studies, 203 (17%) met inclusion criteria for initial evaluation.

Data Extraction and Synthesis

The Meta-analysis of Observational Studies in Epidemiology (MOOSE) and Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guidelines were reporting guideline was followed. Data were extracted by multiple independent reviewers. Risk of death, cancer-specific mortality, and recurrence were pooled to provide an adjusted hazard ratio (HR) with a 95% CI . A random-effects model was used for the retrospective nature of studies.

Main Outcomes and Measures

The primary outcome of the study was overall survival (OS) in patients with cancer, with and without obesity. Secondary end points were cancer-specific survival (CSS) and progression-free survival (PFS) or disease-free survival (DFS). The risk of events was reported as HRs with 95% CIs, with an HR greater than 1 associated with a worse outcome among patients with obesity vs those without.

Results

A total of 203 studies with 6 320 365 participants evaluated the association of OS, CSS, and/or PFS or DFS with obesity in patients with cancer. Overall, obesity was associated with a reduced OS (HR, 1.14; 95% CI, 1.09-1.19; P < .001) and CSS (HR, 1.17; 95% CI, 1.12-1.23; P < .001). Patients were also at increased risk of recurrence (HR, 1.13; 95% CI, 1.07-1.19; P < .001). Conversely, patients with obesity and lung cancer, renal cell carcinoma, or melanoma had better survival outcomes compared with patients without obesity and the same cancer (lung: HR, 0.86; 95% CI, 0.76-0.98; P = .02; renal cell: HR, 0.74; 95% CI, 0.53-0.89; P = .02; melanoma: HR, 0.74; 95% CI, 0.57-0.96; P < .001).

Conclusions and Relevance

In this study, obesity was associated with greater mortality overall in patients with cancer. However, patients with obesity and lung cancer, renal cell carcinoma, and melanoma had a lower risk of death than patients with the same cancers without obesity. Weight-reducing strategies may represent effective measures for reducing mortality in these patients.

Mammary Adipose Tissue Control of Breast Cancer Progression: Impact of Obesity and Diabetes

Mammary adipose tissue (AT) is necessary for breast epithelium. However, in breast cancer (BC), cell-cell interactions are deregulated as the tumor chronically modifies AT microenvironment. In turn, breast AT evolves to accommodate the tumor, and to participate to its dissemination. Among AT cells, adipocytes and their precursor mesenchymal stem cells (MSCs) play a major role in supporting tumor growth and dissemination. They provide energy supplies and release a plethora of factors involved in cancer aggressiveness. Here, we discuss the main molecular mechanisms underlining the interplay between adipose (adipocytes and MSCs) and BC cells. Following close interactions with BC cells, adipocytes lose lipids and change morphology and secretory patterns. MSCs also play a major role in cancer progression. While bone marrow MSCs are recruited by BC cells and participate in metastatic process, mammary AT-MSCs exert a local action by increasing the release of cytokines, growth factors and extracellular matrix components and become principal actors in cancer progression. Common systemic metabolic diseases, including obesity and diabetes, further modify the interplay between AT and BC. Indeed, metabolic perturbations are accompanied by well-known alterations of AT functions, which might contribute to worsen cancer phenotype. Here, we highlight how metabolic alterations locally affect mammary AT and interfere with the molecular mechanisms of bidirectional communication between adipose and cancer cells.

Metabolic syndrome and early stage breast cancer outcome: results from a prospective observational study

PURPOSE

Obesity and insulin resistance have been associated with poor prognosis in breast cancer (BC). The present prospective study aimed to investigate the impact of metabolic syndrome (MetS) and its components on early BC (eBC) patients' outcome.

METHODS

MetS was defined by the presence of 3 to 5 of the following components: waist circumference > 88 cm, blood pressure ≥ 130/≥ 85 mmHg, serum levels of triglycerides ≥ 150 mg/dL, high density lipoprotein < 50 mg/dL and fasting glucose ≥ 110 mg/dL. Seven hundred and seventeen patients with data on ≥ 4 MetS components at BC diagnosis were enrolled. Study population was divided into two groups: patients with < 3 (non-MetS) vs. ≥ 3 components (MetS). Categorical variables were analyzed by Chi-square test and survival data by log-rank test and Cox proportional hazards regression model.

RESULTS

Overall, 544 (75.9%) and 173 (24.1%) women were categorized as non-MetS and MetS, respectively. MetS patients were more likely to be older, postmenopausal, and insulin-resistant compared to non-MetS patients (p < 0.05). In multivariate analysis, MetS patients had a numerically higher risk of relapse [disease-free survival (DFS), hazard ratio (HR) 1.51, p = 0.07] and a significantly higher risk of death compared to non-MetS patients [overall survival (OS), HR 3.01, p < 0.0001; breast cancer-specific survival (BCSS), HR 3.16, p = 0.001]. Additionally, patients with 1 to 2 components of MetS had an increased risk of dying compared to patients with 0 components (OS, HR 4.90, p = 0.01; BCSS, HR 6.07, p = 0.02).

CONCLUSIONS

MetS correlated with poor outcome in eBC patients. Among patients without full criteria for MetS diagnosis, the presence of 1 or 2 components of the syndrome may predict for worse survival.

Novel breast cancer screening: combined expression of miR-21 and MMP-1 in urinary exosomes detects 95% of breast cancer without metastasis

Serum and tissue miR-21 expression in patients with breast cancer (BC) is a useful biomarker for cancer diagnosis, progression, and treatment. Matrix metalloproteinase-1 (MMP-1) is also important in breast cancer carcinogenesis. However, miR-21 and MMP-1/CD63 in urine exosomes in these patients have not been examined. Urine samples were collected from patients with BC and 26 healthy females. Urinary exosomes were isolated and confirmed by western blotting with anti-CD63 antibody and electron microscopy observation. MiR-21 and MMP-1/CD63 expression was examined by quantitative RT-PCR and western blotting, respectively. Patients with very early stage breast cancer were evaluated. MiR-21 expression in the patients was 0.26 [95% CI: 0.20–0.78], which was significant lower than in the 26 controls (1.00 [95% CI: 1.01–3.37], p = 0.0947). MMP-1/CD63 expression in patients was significantly higher than in controls (1.74 [95% CI: 0.86–5.08] vs 0.535 [95% CI: −0.01–2.81], p = 0.0001). Sensitivity and specificity were 0.708 and 0.783 for miR-21 and 0.792 and 0.840 for MMP-1/CD63, respectively. Sensitivity and specificity of combined expression were 95% and 79%, respectively. The sensitivity of MMP-1/CD63 expression in urinary exosomes was better than that of miR-21 expression. Thus, miR-21 and MMP/CD63 may be useful markers for BC screening.

Correlation between renin-angiotensin system (RAS) related genes, type 2 diabetes, and cancer: Insights from metanalysis of transcriptomics data

Although studies have provided significant evidence about the role of RAS in mediating cancer risk in type 2 diabetes mellitus (DM), conclusions about the central molecular mechanisms underlying this disease remain to be reached, because this type of information requires an integrative multi-omics approach. In the current study, meta-analysis was performed on type 2 diabetes and breast, bladder, liver, pancreas, colon and rectum cancer-associated transcriptome data, and reporter biomolecules were identified at RNA, protein, and metabolite levels using the integration of gene expression profiles with genome-scale biomolecular networks in diabetes samples. This approach revealed that RAS biomarkers could be associated with cancer initiation and progression, which include metabolites (particularly, aminoacyl-tRNA biosynthesis and ABC transporters) as novel biomarker candidates and potential therapeutic targets. We detected downregulation and upregulation of differentially expressed genes (DEGs) in blood, pancreatic islets, liver and skeletal muscle from normal and diabetic patients. DEGs were combined with 211 renin-angiotensin-system related genes. Upregulated genes were enriched using Pathway analysis of cancer in pancreatic islets, blood and skeletal muscle samples. It seems that the changes in mRNA are contributing to the phenotypic changes in carcinogenesis, or that they are as a result of the phenotypic changes associated with the malignant transformation. Our analyses showed that Ctsg and Ednrb are downregulated in cancer samples. However, by immunohistochemistry experiments we observed that EDNRB protein showed increased expression in tumor samples. It is true that alterations in mRNA expression do not always reflect alterations in protein expression, since post-translational changes can occur in proteins. In this study, we report valuable data for further experimental and clinical analysis, because the proposed biomolecules have significant potential as systems biomarkers for screening or for therapeutic purposes in type 2 diabetes and cancer-associated pathways.

Cancer and comorbidity: The role of leptin in breast cancer and associated pathologies

Obesity is an important risk factor for postmenopausal breast cancer and also a poor prognostic factor among cancer patients. Moreover, obesity is associated with a number of health disorders such as insulin resistance/type-2 diabetes mellitus, hypertension, and other cardiovascular diseases. Frequently, these health disorders exhibit as components/complications of the metabolic syndrome. Nevertheless, obesity-related diseases may coexist with postmenopausal breast cancer; and these comorbid conditions could be substantial. Therefore, it may be assumed that different diseases including breast cancer could originate from a common pathological background in excessive adipose tissue. Adipocyte-released hormone-like cytokine (or adipokine) leptin behaves differently in a normal healthy state and obesity. A growing body of evidence suggests an important role of leptin in our major obesity-related health issues such as insulin resistance, hypertension, and neoplasia. In this context, this review describes the relationships of the abovementioned pathologies with leptin.

Type 2 diabetes as a predictor of survival among breast cancer patients: the multiethnic cohort

PURPOSE

The purpose of the study was to investigate the association of type 2 diabetes (T2D) with survival of breast cancer (BC) patients across five ethnic groups within the Multiethnic Cohort study.

METHODS

Between recruitment in 1993-1996 and 2013, 7570 incident BC cases were identified through SEER cancer registries in Hawaii and California. T2D diagnosed before BC was ascertained in 1013 women from self-reports and confirmed by administrative data sources. Covariate information was collected by questionnaire. Cox regression analysis with age as the time metric and BMI as time-varying exposure was applied to estimate hazard ratios (HR) and 95% confidence intervals (CI) for BC-specific and all-cause survival while adjusting for known prognostic factors.

RESULTS

In total, 2119 all-cause and 730 BC-specific deaths were recorded with corresponding 5-year survival rates of 86 and 93%. T2D was not a significant predictor of BC-specific survival (HR 0.84; 95% CI 0.65-1.09), but mortality was 36% lower for those with < 7 years of T2D than a longer history of T2D. On the other hand, all-cause mortality was higher in women with T2D (HR 1.23; 95% CI 1.08-1.40), especially in women with T2D of ≥ 7 years duration (HR 1.27; 95% CI 1.07-1.49). In women receiving none or either chemotherapy or radiation but not both, T2D predicted higher all-cause mortality (P_interaction = 0.004). Variations in the association of T2D with mortality across ethnic groups were small.

CONCLUSIONS

T2D was associated with higher all-cause but not BC-specific mortality among women with BC in the Multiethnic Cohort study. However, T2D affected survival in cases who did not receive both radiation and chemotherapy.