Circulating Adipokines and Inflammatory Markers and Postmenopausal Breast Cancer Risk

Body composition as a potential biomarker of recurrence risk in patients with triple-negative breast cancer

BACKGROUND

Triple-negative breast cancer (TNBC) patients are at increased risk for recurrence compared to other subtypes of breast cancer. Previous evidence showed that adiposity may contribute to worsened cancer control. Current measures of obesity, such as body-mass index (BMI), are poor surrogates of adiposity, while visceral-to-subcutaneous adiposity ratio (VSR), which can be measured from routine computed tomography (CT) imaging, is a direct adiposity measure. We hypothesized that VSR is a stronger predictor of recurrence compared with BMI in patients with TNBC.

MATERIALS AND METHODS

This study includes 162 women with stage I-III TNBC who completed standard of care therapy. Measures of body composition, including VSR, visceral adiposity (VA), and subcutaneous adiposity (SA), were estimated using a semi-automated quantitative imaging tool on CT images of the abdomen at the level of L2-L3. Anthropometric measures included BMI and waist circumference and were obtained from CT images. Associations of adiposity measures and recurrence risk were assessed using Fine and Gray competing risk models with death as a competing risk and age at diagnosis and clinical disease stage as covariates.

RESULTS

During a median follow-up time of 7.1 years, 55 patients had recurrence. The median BMI at baseline was 30.2 [Quartiles: 26.3-35.2]. Body composition was not associated with overall or locoregional recurrence. VSR was significantly associated with an increased risk of distant recurrence, with a subdistribution hazard ratio of 4.25 (95% CI: 1.06-17.02), p = 0.041. By contrast, BMI was not associated with any recurrence risk.

CONCLUSION

Consistent with our hypothesis, VSR was associated with a significant risk of distant recurrence and therefore may be a prognostic biomarker. Future directions include interventions targeting VSR reduction among patients with TNBC and VSR-directed therapy modulation.

Multi-ancestry sequencing-based genome-wide association study of C-reactive protein in 513,273 genomes

C-reactive protein (CRP) serves as a pivotal marker of systemic inflammation, yet its genetic architecture has predominantly been explored within European populations. Our multi-ancestry sequencing-based genome-wide association study (seqGWAS) meta-analysis encompasses 447,369 Europeans, 10,389 Africans, 9685 Asians, and 9200 Hispanics in the discovery set, and 23,521 Europeans, 7160 Africans, 771 Asians, and 5178 Hispanics in the replication set. We identify 113 independent association signals (Pdiscovery ≤ 5 × 10-9 and Preplication ≤ 0.05), including 21 loci that passed the conditional analysis, among which 3 are European-specific. Cross ancestry fine-mapping pinpoints 19 of 113 independent signals within the 95% credible set. Functional annotation reveals significant enrichment in blood tissue, H3K27me3 histone marks, and exonic regions. Leveraging the Polygenic Priority Score (PoPS) and gene-based analyses, we implicate 151 genes as potential regulators of CRP levels, 55 of which have not been previously reported. Among these, 17 genes and four proteins show causal evidence or strong colocalization with CRP-related pathologies.

Proinflammatory dietary pattern and risk of total and subtypes of breast cancer among US women

BACKGROUND

Dietary patterns promoting chronic inflammation, including the empirical dietary inflammatory pattern (EDIP), have been associated with certain cancers. Investigating whether this dietary pattern is associated with breast cancer-where the role of inflammation is less well-defined-could provide valuable insights and potentially improve strategies for preventing this cancer.

METHODS

We prospectively followed 76 386 women from Nurses' Health Study (NHS, 1984-2018) and 92 886 women from Nurses' Health Study II (NHSII, 1991-2019). Diet was assessed by food frequency questionnaires every 4 years, starting at baseline. The inflammatory potential of diet was evaluated using the validated EDIP based on plasma C-reactive protein, interleukin-6, and tumor necrosis factor α-R2. Higher scores indicate higher dietary inflammatory potential. Hazard ratios (HRs) and 95% confidence intervals (CIs) of overall and subtypes of breast cancer were estimated using multivariable-adjusted Cox regression models.

RESULTS

During 4 490 842 person-years of follow-up, we documented 11 026 breast cancer cases. Women in the highest compared with the lowest EDIP quintile were at higher breast cancer risk (HRQ5vsQ1 = 1.12, 95% CI = 1.05 to 1.19; Ptrend < .001). The association was stronger for estrogen receptor negative tumors (HRQ5vsQ1 = 1.29, 95% CI = 1.09 to 1.53; Ptrend = .003). Also, we observed that the association of EDIP with breast cancer risk differed by molecular subtype, with the strongest association observed with basal-like tumors (HRQ5vsQ1 = 1.80, 95% CI = 1.20 to 2.71; Ptrend = .004).

CONCLUSIONS

Higher EDIP scores were associated with a modestly increased risk of breast cancer, which was more pronounced for estrogen receptor negative and basal-like breast tumors. These results support the hypothesis that diet-related inflammation plays a role in breast cancer etiology, particularly tumors lacking hormone receptors.

Inflammation in Penile Squamous Cell Carcinoma: A Comprehensive Review

Inflammation appears to play a crucial role in the development and progression of penile cancer (PeCa). Two molecular pathways of PeCa are currently described: HPV-dependent and HPV-independent. The tumor immune microenvironment (TIME) of PeCa is characterized by the presence of tumor-associated macrophages, cancer-associated fibroblasts, and tumor-infiltrating lymphocytes. The components of the TIME produce pro-inflammatory cytokines and chemokines, which have been found to be overexpressed in PeCa tissues and are associated with tumor progression and unfavorable prognoses. Additionally, the nuclear factor kappa B (NF-κB) pathway and secreted phosphoprotein 1 (SPP1) have been implicated in PeCa pathogenesis. Elevated C-reactive protein (CRP) levels and the neutrophil-to-lymphocyte ratio (NLR) have been identified as potential prognostic biomarkers in PeCa. This overview presents the complex contribution of the inflammatory process and collates projects aimed at modulating TIME in PeCa.

Body composition as a novel biomarker of recurrence risk in patients with triple-negative breast cancer

Background and Hypothesis

Triple-negative breast cancer (TNBC) patients are at increased risk for recurrence compared to other subtypes of breast cancer. Previous evidence showed that adiposity may contribute to worsened cancer control. Current measures of obesity, such as body-mass index (BMI), are poor surrogates of adiposity, while visceral-to-subcutaneous adiposity ratio (VSR), which can be measured from routine computed tomography (CT) imaging, is a direct adiposity measure. We hypothesized that VSR is a stronger predictor of recurrence compared with BMI in patients with TNBC.

Materials and Methods

This study includes 162 women with stage I-III TNBC who completed standard of care therapy. Measures of body composition, including VSR, visceral adiposity (VA), and subcutaneous adiposity (SA), were estimated using a semi-automated quantitative imaging tool on CT images of the abdomen at the level of L2-L3. Anthropometric measures included BMI and waist circumference and were obtained from CT images. Associations of adiposity measures and recurrence risk were assessed using Fine and Gray competing risk models with death as a competing risk and age at diagnosis and clinical disease stage as covariates.

Results

During a median follow-up time of 3.6 years, 55 patients had recurrence. The median BMI at baseline was 30.2 [Quartiles: 26.3-35.2]. Body composition was not associated with overall or locoregional recurrence. VSR was significantly associated with an increased risk of distant recurrence, with a subdistribution hazard ratio of 4.25 (95% CI: 1.06-17.02), p = 0.041. By contrast, BMI was not associated with any recurrence risk.

Conclusion

Consistent with our hypothesis, VSR was associated with a significant risk of distant recurrence and therefore may be a prognostic biomarker. Future directions include interventions targeting VSR reduction among patients with TNBC and VSR-directed therapy modulation.

Metabolite Predictors of Breast and Colorectal Cancer Risk in the Women's Health Initiative

Metabolomics has been used extensively to capture the exposome. We investigated whether prospectively measured metabolites provided predictive power beyond well-established risk factors among 758 women with adjudicated cancers [n = 577 breast (BC) and n = 181 colorectal (CRC)] and n = 758 controls with available specimens (collected mean 7.2 years prior to diagnosis) in the Women's Health Initiative Bone Mineral Density subcohort. Fasting samples were analyzed by LC-MS/MS and lipidomics in serum, plus GC-MS and NMR in 24 h urine. For feature selection, we applied LASSO regression and Super Learner algorithms. Prediction models were subsequently derived using logistic regression and Super Learner procedures, with performance assessed using cross-validation (CV). For BC, metabolites did not increase predictive performance over established risk factors (CV-AUCs~0.57). For CRC, prediction increased with the addition of metabolites (median CV-AUC across platforms increased from ~0.54 to ~0.60). Metabolites related to energy metabolism: adenosine, 2-hydroxyglutarate, N-acetyl-glycine, taurine, threonine, LPC (FA20:3), acetate, and glycerate; protein metabolism: histidine, leucic acid, isoleucine, N-acetyl-glutamate, allantoin, N-acetyl-neuraminate, hydroxyproline, and uracil; and dietary/microbial metabolites: myo-inositol, trimethylamine-N-oxide, and 7-methylguanine, consistently contributed to CRC prediction. Energy metabolism may play a key role in the development of CRC and may be evident prior to disease development.

Increases in BMI contribute to worsening inflammatory biomarkers related to breast cancer risk in women: a longitudinal study

BACKGROUND

Inflammatory adipokines and cytokines play a pivotal role in linking obesity and breast cancer (BC) risk in women. We investigated the longitudinal associations between BMI change and trajectories of inflammatory biomarkers related to BC risk.

METHODS

A longitudinal study was conducted among 442 Chinese women with 3-year repeated measures from 2019 to 2021. Plasma circulating inflammatory biomarkers related to BC risk, including adiponectin (ADP), resistin (RETN), soluble leptin receptor (sOB-R), insulin-like growth factor-binding protein-3 (IGFBP-3), and C-reactive protein (CRP), were examined annually. Linear mixed-effect models (LMM) were applied to investigate associations of time-varying BMI with trajectories of biomarkers. We additionally examined the modification effect of baseline BMI groups, menopausal status, and metabolic syndrome.

RESULTS

BMI was associated with increased levels of RETN, CRP, sOB-R, and decreased levels of ADP at baseline. An increasing BMI rate was significantly associated with an average 3-year increase in RETN (β = 0.019, 95% CI 0.004 to 0.034) and sOB-R (β = 0.022, 95% CI 0.009 to 0.035), as well as a decrease in ADP (β =  - 0.006, 95% CI  - 0.012 to 0.001). These associations persisted across different baseline BMI groups. An increasing BMI rate was significantly associated with an average 3-year increase in CRP levels among normal weight (β = 0.045, 95% CI 0.001 to 0.088) and overweight (β = 0.060, 95% CI 0.014 to 0.107) women. As BMI increased over time, a more remarkable decrease in ADP was observed among women with metabolic syndrome (β =  - 0.016, 95% CI - 0.029 to - 0.004) than those without metabolic syndrome at baseline.

CONCLUSIONS

A higher increase rate of BMI was associated with poorer trajectories of inflammatory biomarkers related to BC risk. Recommendations for BMI reduction may benefit BC prevention in women, particularly for those with metabolic syndrome.

Masoprocol: a promising candidate for targeting insulin resistance by inhibiting resistin with optimal druglikeness Potentials: an in silico approach

Resistin is a cysteine-rich secretory hormone that induces resistance to insulin, and its elevated expression is correlated with the onset of diabetes and several related metabolic disorders. Resistin performs its inhibitory role by connecting three identical subunits through Cys22-based disulfide linkages. The necessity to inhibit the formation of resistin trimer is one of the essential means to prevent the aggravation of diabetes mellitus type 2, obesity, and atherosclerosis. This study was conducted to screen the clinically approved drugs to find the most potent one to inhibit resistin with the best pharmacokinetics and drug-likeness properties. A total of 4654 clinically approved drugs were docked against the Cys22 residue of resistin. The top ten drugs with the highest high-precision (XP) docking scores were selected. Ioversol and masoprocol showed the highest XP docking and Molecular Mechanics-Generalized Born Surface Area (MMGBSA) scores, respectively, with double hydrogen bonding with the targeted Cys22. Molecular dynamics (MD) simulations showed that the masoprocol-resistin complex exhibited lower root mean square deviation (RMSD), radius of gyration, and root mean square fluctuation (RMSF) values than those observed in the ioversol-resistin complex. Both drugs induced drastic conformational changes in resistin monomer interactions. However, ioversol did not prove satisfying drug-likeness properties, while masoprocol showed the most favourable pharmacokinetic and drug-likeness properties. This study has demonstrated that masoprocol offers a novel inhibitory effect on resistin with the highest ligand affinity, making it a promising drug for combating insulin resistance.Communicated by Ramaswamy H. Sarma.

Leptin: A Heavyweight Player in Obesity-Related Cancers

Obesity, defined as the abnormal or excessive expansion of white adipose tissue, has reached pandemic proportions and is recognized as an important health concern since it is a common root for several comorbidities, including malignancies. Indeed, the current knowledge of the white adipose tissue, which shifts its role from an energy storage tissue to an important endocrine and metabolic organ, has opened up new avenues for the discovery of obesity's effects on tumor biology. In this review, we will report the epidemiological studies concerning the strong impact of obesity in several types of cancer and describe the mechanisms underlying the heterotypic signals between cancer cell lines and adipocytes, with particular emphasis on inflammation, the insulin/IGF-1 axis, and adipokines. Among the adipokines, we will further describe the in vitro, in vivo, and clinical data concerning the role of leptin, recognized as one of the most important mediators of obesity-associated cancers. In fact, leptin physiologically regulates energy metabolism, appetite, and reproduction, and several studies have also described the role of leptin in affecting cancer development and progression. Finally, we will summarize the newest pharmacological strategies aimed at mitigating the protumorigenic effects of leptin, underlining their mechanisms of action.

Linking Physical Activity to Breast Cancer via Inflammation, Part 2: The Effect of Inflammation on Breast Cancer Risk

This review synthesized and appraised the evidence for an effect of inflammation on breast cancer risk. Systematic searches identified prospective cohort and Mendelian randomization studies relevant to this review. Meta-analysis of 13 biomarkers of inflammation were conducted to appraise the evidence for an effect breast cancer risk; we examined the dose-response of these associations. Risk of bias was evaluated using the ROBINS-E tool and the quality of evidence was appraised with Grading of Recommendations Assessment, Development, and Evaluation. Thirty-four observational studies and three Mendelian randomization studies were included. Meta-analysis suggested that women with the highest levels of C-reactive protein (CRP) had a higher risk of developing breast cancer [risk ratio (RR) = 1.13; 95% confidence interval (CI), 1.01-1.26] compared with women with the lowest levels. Women with highest levels of adipokines, particularly adiponectin (RR = 0.76; 95% CI, 0.61-0.91) had a reduced breast cancer risk, although this finding was not supported by Mendelian randomization analysis. There was little evidence of an effect of cytokines, including TNFα and IL6, on breast cancer risk. The quality of evidence for each biomarker ranged from very low to moderate. Beyond CRP, the published data do not clearly support the role of inflammation in the development of breast cancer.

Comprehensive prognostic effects of systemic inflammation and Insulin resistance in women with breast cancer with different BMI: a prospective multicenter cohort

To investigate the prognostic value of systemic inflammation and insulin resistance in women with breast cancer with different body mass index (BMI). This multicenter, prospective study included 514 women with breast cancer. Multivariate survival analysis showed that patients with high C-reactive protein (CRP), high CRP to albumin ratio (CAR), high lymphocyte to CRP ratio (LCR), high low-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio (LHR), and high triglyceride to high-density lipoprotein cholesterol ratio (TG/HDL-c) were significantly associated with worse prognosis. The mortality rate of patients with both high CAR and high LHR or both low LCR and high LHR were 3.91-fold or 3.89-fold higher than patients with both low CAR and low LHR or both high LCR and low LHR, respectively. Furthermore, the combination of LCR and LHR significantly predicted survival in patients within the high BMI group. The CRP, CAR, LCR, LHR, and TG/HDL-c were associated with poor survival in women with breast cancer. The combination of CAR and LHR or LCR and LHR could better predict the prognostic outcomes of women with breast cancer, while the combination of LCR and LHR could better predict the prognosis of those patients with overweight or obese patients.

The EASO New Investigator Award in Clinical Research 2021: Role of Chronotype in Obesity

BACKGROUND

Chronotype is the expression of the timing of circadian rhythmicity of a subject, and three categories of chronotype have been identified: morning, evening, and intermediate chronotype. Subjects with morning chronotype prefer to carry out most of their daily activities in the morning, while subjects with evening chronotype perform most of their daily activities in the second half of the day. Intermediate chronotype is in an intermediate position between the above reported categories. Recently, evening chronotype has been associated with an increased risk of developing chronic diseases. Thus, the aim of this manuscript was to review the current evidence on the role of chronotype categories on the risk of developing obesity and the most common obesity-related comorbidities (cardiometabolic and neoplastic complications).

SUMMARY

Subjects with evening chronotype have been reported to be at high risk of developing obesity, and this was mostly due to the tendency of these subjects to follow unhealthy lifestyle mostly characterized by sedentary behavior and high intake of unhealthy food. In addition, sleep disturbances are a common finding in subjects with evening chronotype that in turn could further contribute to the risk of obesity. The impairment of insulin sensitivity, melatonin, adiponectin, and clock genes function along with increase of leptin secretion detected in subjects with evening chronotype could also represent a favorable milieu for the onset of obesity-related cancer. The current evidence is limited to breast, prostate, and endometrial cancer.

KEY MESSAGES

The chronotype categories could be easy assessed in subjects with obesity and at the same time provide an important information on an additional risk factor predisposing to the onset of obesity-related comorbidities. Since chronotype could be potentially modified through a behavioral-driven approach thus potentiating the efficacy of anti-obesity treatment, the assessment of chronotype categories should be included in the management of obesity.

Abbas S, G. Shareef L. Impact of serum leptin and adiponectin levels on breast cancer in postmenopausal Iraqi women: an observational Study

Background:  Breast cancer is the most common malignant tumor and the second most significant cause of death for women in Iraq, behind cardiovascular diseases. Obesity has been linked to a substantial increase in the risk of breast cancer. Adipose tissue functions as an endocrine gland, controlling the body's metabolism by secreting adipokines, which play a significant role in metabolism and inflammatory reactions. Methods: Overall, 90 postmenopausal women participated in this research. Of these, 60 patients with breast cancer were recruited at Baghdad's Oncology Teaching Hospital between October 2021 and February 2022: 30 were obese with a body mass index (BMI) of > 30 kg/m2 (group 1), and 30 were not obese (group 2). The third group consisted of 30 participants without breast cancer or obesity (group 3). Each person donated five milliliters of venous blood. The blood levels of adiponectin and leptin are determined using enzyme-linked immunosorbent assay (ELISA) kits. Results: Control individuals who were not obese (group 3) had greater blood adiponectin levels than patients with cancer who were both obese and non-obese (groups 1 and 2), with no significant difference in serum adiponectin levels seen between groups 1 and 2. The findings also showed that group 1 (patients with breast cancer and obesity) had greater serum leptin levels than both group 2 (patients with breast cancer without obesity) and the control group (group 3), with no significant difference in serum leptin levels between groups 2 and 3. Conclusions: Adiponectin levels in the blood of women with breast cancer and obesity were low which may be due to high BMI, which reduces adiponectin's protective effects. Conversely, Leptin levels were more significant in the blood of women with breast cancer and obesity than in the control group, which may be due to its pro-inflammatory effects in obesity, among other variables.

Linking Physical Activity to Breast Cancer Risk via the Insulin/Insulin-like Growth Factor Signaling System, Part 2: The Effect of Insulin/Insulin-like Growth Factor Signaling on Breast Cancer Risk

Perturbation of the insulin/insulin-like growth factor (IGF) signaling system is often cited as a mechanism driving breast cancer risk. A systematic review identified prospective cohort studies and Mendelian randomization studies that examined the effects of insulin/IGF signaling (IGF, their binding proteins (IGFBP), and markers of insulin resistance] on breast cancer risk. Meta-analyses generated effect estimates; risk of bias was assessed and the Grading of Recommendations Assessment, Development and Evaluation system applied to evaluate the overall quality of the evidence. Four Mendelian randomization and 19 prospective cohort studies met our inclusion criteria. Meta-analysis of cohort studies confirmed that higher IGF-1 increased risk of breast cancer; this finding was supported by the Mendelian randomization studies. IGFBP-3 did not affect breast cancer. Meta analyses for connecting-peptide and fasting insulin showed small risk increases, but confidence intervals were wide and crossed the null. The quality of evidence obtained ranged from 'very low' to 'moderate'. There were insufficient studies to examine other markers of insulin/IGF signaling. These findings do not strongly support the biological plausibility of the second part of the physical activity-insulin/IGF signaling system-breast cancer pathway. Robust conclusions cannot be drawn due to the dearth of high quality studies. See related article by Swain et al., p. 2106.

Systematic review and meta-analysis of C-reactive protein as a biomarker in breast cancer

Inflammation is an enabling characteristic of the hallmarks of cancer. There has therefore been increasing interest in the clinical value of circulating inflammatory biomarkers in cancer. In this review, we summarize results on C-reactive protein (CRP), alone or as part of the Glasgow Prognostic Score (GPS, composed of CRP and serum albumin), as a biomarker of prognosis or prediction and monitoring of therapeutic response in patients with breast cancer. A systematic literature search was performed in Medline and Embase from 1990 to August 2021. The association of serum CRP and overall survival and disease/progression-free survival was summarized in meta-analyses using a random effects model. The results from a total of 35 included studies (20,936 patients) were divided according to three identified patient settings (metastatic, non-metastatic, and general setting). Most of the studies examined prognostic utility. Several larger studies observed associations between high serum CRP and poor survival, but the meta-analyses suggested a limited value in a non-metastatic and general breast cancer setting (populations with unknown or varied disease stage). In metastatic patients, however, more consistent findings supported an association between serum CRP and prognosis (hazard ratio for overall survival: 1.87 (95% CI 1.31-2.67). Only five studies examined a role in prediction or monitoring of therapeutic response. One study reported a significant association between serum CRP levels and response to chemotherapy. Findings regarding serum CRP as a biomarker in breast cancer appear inconsistent, particularly in non-metastatic and general breast cancer, where the prognostic value could not be confirmed. In patients with metastatic breast cancer we suggest that high serum CRP is an indicator of poor prognosis. Too few studies assessed the role of serum CRP in prediction or monitoring of treatment response to allow conclusions.

C-reactive protein and cancer risk: a pan-cancer study of prospective cohort and Mendelian randomization analysis

BACKGROUND

Although observational studies have reported associations between serum C-reactive protein (CRP) concentration and risks of lung, breast, and colorectal cancer, inconsistent or absent evidences were showed for other cancers. We conducted a pan-cancer analysis to comprehensively assess the role of CRP, including linearity and non-linearity associations.

METHODS

We analyzed 420,964 cancer-free participants from UK Biobank cohort. Multivariable-adjusted Cox proportional hazards model was conducted to evaluate the observed correlation of CRP with overall cancer and 21 site-specific cancer risks. Furthermore, we performed linear and non-linear Mendelian randomization analyses to explore the potential causal relation between them.

RESULTS

During a median follow-up period of 7.1 years (interquartile range: 6.3, 7.7), 34,979 incident cancer cases were observed. Observational analyses showed higher CRP concentration was associated with increased risk of overall cancer (hazard ratio (HR) = 1.02, 95% CI: 1.01, 1.02 per 1mg/L increase, P < 0.001). There was a non-linear association between CRP and overall cancer risk with inflection point at 3mg/L (false-discovery rate adjust (FDR-adjusted) P_overall < 0.001 and FDR-adjusted P_non-linear < 0.001). For site-specific cancer, we observed positive linear associations for cancers of esophagus and stomach (FDR-adjusted P_overall < 0.050 and FDR-adjusted P_non-linear > 0.050). In addition, we also observed three different patterns of non-linear associations, including "fast-to-low increase" (head and neck, colorectal, liver, lung, kidney cancer, and non-Hodgkin lymphoma), "increase-to-decrease" (breast cancer), and "decrease-to-platform" (chronic lymphocytic leukemia). Furthermore, the inflection points of non-linear association patterns were consistently at around 3mg/L. By contrast, there was no evidence for linear or non-linear associations between genetically predicted CRP and risks of overall cancer or site-specific cancers.

CONCLUSIONS

Our results indicated that CRP was a potential biomarker to assess risks of overall cancer and 12 site-specific cancers, while no association were observed for genetically-predicted CRP and cancer risks.

Circulating inflammatory biomarkers, adipokines and breast cancer risk-a case-control study nested within the EPIC cohort

BACKGROUND

Inflammation has been hypothesized to play a role in the development and progression of breast cancer and might differently impact breast cancer risk among pre and postmenopausal women. We performed a nested case-control study to examine whether pre-diagnostic circulating concentrations of adiponectin, leptin, c-reactive protein (CRP), tumour necrosis factor-α, interferon-γ and 6 interleukins were associated with breast cancer risk, overall and by menopausal status.

METHODS

Pre-diagnostic levels of inflammatory biomarkers were measured in plasma from 1558 case-control pairs from the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. We used conditional logistic regression to estimate the odds ratios (ORs) of breast cancer at blood collection, per one standard deviation increase in biomarker concentration.

RESULTS

Cases were diagnosed at a mean age of 61.4 years on average 8.6 years after blood collection. No statistically significant association was observed between inflammatory markers and breast cancer risk overall. In premenopausal women, borderline significant inverse associations were observed for leptin, leptin-to-adiponectin ratio and CRP [OR= 0.89 (0.77-1.03), OR= 0.88 (0.76-1.01) and OR= 0.87 (0.75-1.01), respectively] while positive associations were observed among postmenopausal women [OR= 1.16 (1.05-1.29), OR= 1.11 (1.01-1.23), OR= 1.10 (0.99-1.22), respectively]. Adjustment for BMI strengthened the estimates in premenopausal women [leptin: OR = 0.83 (0.68-1.00), leptin-to-adiponectin ratio: OR = 0.80 (0.66-0.97), CRP: OR = 0.85 (0.72-1.00)] but attenuated the estimates in postmenopausal women [leptin: OR = 1.09 (0.96-1.24), leptin-to-adiponectin ratio: OR = 1.02 (0.89-1.16), CRP: OR = 1.04 (0.92-1.16)].

CONCLUSIONS

Associations between CRP, leptin and leptin-to-adiponectin ratio with breast cancer risk may represent the dual effect of obesity by menopausal status although this deserves further investigation.

The first combined meta‐analytic approach for elucidating the relationship of circulating resistin levels and RETN gene polymorphisms with colorectal and breast cancer

Background

Evidence suggests that circulating resistin levels are altered in colorectal cancer (CRC) and breast cancer (BC). Again, polymorphisms in resistin-encoding gene RETN have been evaluated in CRC and BC. However, there is a scarcity of data establishing the relationship of resistin and RETN polymorphisms (rs1862513 and rs3745367) with these cancers. This study aimed to analyze the relationship of resistin levels and RETN polymorphisms with CRC and BC in a combined meta-analytic approach.

Main body of the abstract

After a comprehensive online literature search, screening and eligibility check, 41 articles (31 with resistin level and 10 with RETN polymorphisms) were retrieved for meta-analyses. The mean difference (MD) of resistin was calculated and pooled to investigate the effect sizes with a 95% confidence interval (CI), and the connection of genetic polymorphisms was analyzed with an odds ratio (OR) and 95% CI. The analysis showed that resistin level is significantly higher in CRC (MD = 3.39) and BC (MD = 3.91) patients. Subgroup analysis in CRC showed significantly higher resistin in serum (MD = 4.61) and plasma (MD = 0.34), and in BC, a significantly elevated resistin level was reported in premenopausal (MD = 7.82) and postmenopausal (MD = 0.37) patients. Again, RETN rs1862513 showed a significantly strong association with CRC (codominant 1—OR 1.24, codominant 2—OR 1.31, dominant model—OR 1.25, and allele model—OR 1.16) and with BC (codominant 2—OR 1.51, codominant 3—OR 1.51, recessive model—OR 1.51, and allele model—OR 1.21). RETN rs3745367 did not show any association with these cancers.

Short conclusion

Overall, our analysis indicates that higher circulating resistin levels are associated with an elevated risk of CRC and premenopausal and postmenopausal BC. Besides, rs1862513 in RETN gene is significantly connected with both CRC and BC.

Obesity and breast cancer: Preventive and therapeutic possibilities for bariatric surgery

Breast cancer is the most common and second deadliest malignancy in women. With rising obesity rates and building evidence for a strong association with obesity, the incidence of breast cancer can be expected to increase. Weight loss reduces breast cancer risk, the mechanisms of which are still poorly understood. As an effective therapy for obesity, bariatric surgery may be a powerful tool in breast cancer prevention and treatment. This review details the potential physiologic mechanisms that may underlie this association, as well as recently published studies that reinforce the link between bariatric surgery and a reduction in incident breast cancer. The use of bariatric surgery as an adjunct therapy in endometrial cancer also raises the potential for similar use in select breast cancer patients. Despite the expanding potential applications of bariatric surgery in this field, publications to date have been strictly observational, highlighting a need for future clinical trials.

Adiposity and breast, endometrial, and colorectal cancer risk in postmenopausal women: Quantification of the mediating effects of leptin, C-reactive protein, fasting insulin, and estradiol

BACKGROUND

Mechanisms underlying the adiposity-cancer relationship are incompletely understood. We quantified the mediating roles of C-reactive protein (CRP), leptin, fasting insulin, and estradiol in the effect of adiposity on estrogen receptor (ER)-positive breast, endometrial, and colorectal cancer risk in postmenopausal women.

METHODS

We used a case-cohort study within the Women's Health Initiative Observational Study, analyzed as a cumulative sampling case-control study. The study included 188 breast cancer cases, 98 endometrial cancer cases, 193 colorectal cancer cases, and 285 controls. Interventional indirect and direct effects on the risk ratio (RR) scale were estimated using causal mediation analysis.

RESULTS

For breast cancer, the total effect RR for BMI ≥30 versus ≥18.5-<25 kg/m2 was 1.87 (95%CI,1.11-3.13). The indirect effect RRs were 1.38 (0.79-2.33) through leptin and CRP, 1.58 (1.17-2.43) through insulin, and 1.11 (0.98-1.30) through estradiol. The direct effect RR was 0.82 (0.39-1.68). For endometrial cancer, the total effect RR was 2.12 (1.12-4.00). The indirect effect RRs were 1.72 (0.85-3.98) through leptin and CRP, 1.42 (0.96-2.26) through insulin, and 1.24 (1.03-1.65) through estradiol. The direct effect RR was 0.70 (0.23-2.04). For colorectal cancer, the total effect RR was 1.70 (1.03-2.79). The indirect effect RRs were 1.04 (0.61-1.72) through leptin and CRP, 1.36 (1.00-1.88) through insulin, and 1.02 (0.88-1.17) through estradiol. The direct effect RR was 1.16 (0.58-2.43).

CONCLUSION

Leptin, CRP, fasting insulin, and estradiol appear to mediate the effect of high BMI on cancer risk to different extents, with likely varying degrees of importance between cancers. These insights might be important in developing interventions to modify obesity-associated cancer risk in postmenopausal women.

A review of research on the intersection between breast cancer and cardiovascular research in the Women's Health Initiative (WHI)

Both obesity and metabolic syndrome are linked to increased incidence of type 2 diabetes, cardiovascular disease (CVD), and cancers of the breast (post-menopausal), and other obesity-related cancers. Over the past 50 years, the worldwide prevalence of obesity and metabolic syndrome has increased, with a concomitant higher incidence of associated co-morbidities and mortality. The precise mechanism linking metabolic syndrome to increased cancer incidence is incompletely understood, however, individual components of metabolic syndrome have been linked to increased breast cancer incidence and worse survival. There is a bidirectional relationship between the risk of CVD and cancer due to a high burden of shared risk factors and higher rates of CVD among cancer survivors, which may be impacted by the pro-inflammatory microenvironment associated with metabolic syndrome and cancer-directed therapies. The Women's Health Initiative (WHI) is an excellent resource to study a dual relationship between cancer and CVD (cardio-oncology) with extensive information on risk factors and long-term outcomes. The purpose of this review is to provide an overview of research on cardio-oncology conducted utilizing WHI data with focus on studies evaluating both breast cancer and CVD including shared risk factors and outcomes after cancer. The review also includes results on other obesity related cancers which were included in the analyses of breast cancer, articles looking at cancer after heart disease (reverse cardio-oncology) and the role of Clonal Hematopoiesis of Indeterminate Potential (CHIP) as a shared risk factor between CVD and cancer. A summary of pertinent WHI literature helps to delineate the direction of future research evaluating the relationship between CVD and other cancer sites, and provides information on the opportunity for other novel analyses within the WHI.

Association of circulating leptin, adiponectin, and resistin concentrations with long-term breast cancer prognosis in a German patient cohort

Adipokines including leptin, adiponectin and resistin have been linked to risk of obesity-related cancers potentially through low-grade chronic inflammation pathways. We aimed to assess the role of post-diagnosis circulating adipokines on long-term prognosis in a prospective breast cancer cohort. Adipokines were measured in blood collected at baseline shortly after diagnosis (2002-2005) and at follow-up (2009) from 3112 breast cancer patients enrolled in the population-based MARIE study. Half of the patients had measurements at both time-points. All-cause mortality, breast cancer specific mortality and recurrences were ascertained up to June 2015 (11 years median follow-up). Associations with time-varying adipokine concentrations overall and stratified by estrogen and progesterone receptor (ERPR) were evaluated using adjusted proportional hazard regression. At baseline (n = 2700) and follow-up (n = 2027), median concentrations for leptin, adiponectin and resistin were 4.6 and 2.7 ng/ml, 24.4 and 30.0 mg/l, 15.4 and 26.2 ng/ml, respectively. After adjustment, there was no evidence for associations between adipokines and any outcome overall. In ERPR negative tumors, highest vs. lowest quintile of adiponectin was significantly associated with increased breast cancer specific mortality (HR 2.51, 95%CI 1.07-5.92). Overall, post-diagnosis adipokines were not associated with long-term outcomes after breast cancer. In patients with ERPR negative tumors, higher concentrations of adiponectin may be associated with increased breast cancer specific mortality and warrant further investigation.

Change in Blood and Benign Breast Biomarkers in Women Undergoing a Weight-Loss Intervention Randomized to High-Dose ω-3 Fatty Acids versus Placebo

The inflammation-resolving and insulin-sensitizing properties of eicosapentaenoic (EPA) and docosahexaenoic (DHA) fatty acids have potential to augment effects of weight loss on breast cancer risk. In a feasibility study, 46 peri/postmenopausal women at increased risk for breast cancer with a body mass index (BMI) of 28 kg/m² or greater were randomized to 3.25 g/day combined EPA and DHA (ω-3-FA) or placebo concomitantly with initiation of a weight-loss intervention. Forty-five women started the intervention. Study discontinuation for women randomized to ω-3-FA and initiating the weight-loss intervention was 9% at 6 months and thus satisfied our main endpoint, which was feasibility. Between baseline and 6 months significant change (P < 0.05) was observed in 12 of 25 serum metabolic markers associated with breast cancer risk for women randomized to ω-3-FA, but only four for those randomized to placebo. Weight loss (median of 10% for trial initiators and 12% for the 42 completing 6 months) had a significant impact on biomarker modulation. Median loss was similar for placebo (-11%) and ω-3-FA (-13%). No significant change between ω-3-FA and placebo was observed for individual biomarkers, likely due to sample size and effect of weight loss. Women randomized to ω-3-FA exhibiting more than 10% weight loss at 6 months showed greatest biomarker improvement including 6- and 12-month serum adiponectin, insulin, omentin, and C-reactive protein (CRP), and 12-month tissue adiponectin. Given the importance of a favorable adipokine profile in countering the prooncogenic effects of obesity, further evaluation of high-dose ω-3-FA during a weight-loss intervention in obese high-risk women should be considered. PREVENTION RELEVANCE: This study examines biomarkers of response that may be modulated by omega-3 fatty acids when combined with a weight-loss intervention. While focused on obese, postmenopausal women at high risk for development of breast cancer, the findings are applicable to other cancers studied in clinical prevention trials.

Association of CYP2D6 genotype and tamoxifen metabolites with breast cancer recurrence in a low-dose trial

Low-dose tamoxifen halves recurrence in non-invasive breast cancer without significant adverse events. Some adjuvant trials with tamoxifen 20 mg/day had shown an association between low endoxifen levels (9–16 nM) and recurrence, but no association with CYP2D6 was shown in the NSABP P1 and P2 prevention trials. We studied the association of CYP2D6 genotype and tamoxifen metabolites with tumor biomarkers and recurrence in a randomized phase III trial of low-dose tamoxifen. Median (IQR) endoxifen levels at year 1 were 8.4 (5.3–11.4) in patients who recurred vs 7.5 (5.1–10.2) in those who did not recur (p = 0.60). Tamoxifen and metabolites significantly decreased C-reactive protein (CRP, p < 0.05), and a CRP increase after 3 years was associated with higher risk of recurrence (HR = 4.37, 95% CI, 1.14–16.73, P = 0.03). In conclusion, endoxifen is below 9 nM in most subjects treated with 5 mg/day despite strong efficacy and there is no association with recurrence, suggesting that the reason for tamoxifen failure is not poor drug metabolism. Trial registration: ClinicalTrials.gov, Identifier: NCT01357772.

Effects of Adiposity and Exercise on Breast Tissue and Systemic Metabo-Inflammatory Factors in Women at High Risk or Diagnosed with Breast Cancer

Excess body fat and sedentary behavior are associated with increased breast cancer risk and mortality, including in normal weight women. To investigate underlying mechanisms, we examined whether adiposity and exercise impact the breast microenvironment (e.g., inflammation and aromatase expression) and circulating metabo-inflammatory factors. In a cross-sectional cohort study, breast white adipose tissue (WAT) and blood were collected from 100 women undergoing mastectomy for breast cancer risk reduction or treatment. Self-reported exercise behavior, body composition measured by dual-energy x-ray absorptiometry (DXA), and waist:hip ratio were obtained prior to surgery. Breast WAT inflammation (B-WATi) was assessed by IHC and aromatase expression was assessed by quantitative PCR. Metabolic and inflammatory blood biomarkers that are predictive of breast cancer risk and progression were measured. B-WATi was present in 56 of 100 patients and was associated with older age, elevated BMI, postmenopausal status, decreased exercise, hypertension and dyslipidemia (Ps < 0.001). Total body fat and trunk fat correlated with B-WATi and breast aromatase levels (Ps < 0.001). Circulating C-reactive protein, IL6, insulin, and leptin positively correlated with body fat and breast aromatase levels, while negative correlations were observed for adiponectin and sex hormone binding globulin (P < 0.001). Inverse relationships were observed with exercise (Ps < 0.05). In a subgroup of 39 women with normal BMI, body fat levels positively correlated with B-WATi and aromatase expression (Ps < 0.05). In conclusion, elevated body fat levels and decreased exercise are associated with protumorigenic micro- and host environments in normal, overweight, and obese individuals. These findings support the development of BMI-agnostic lifestyle interventions that target adiposity. PREVENTION RELEVANCE: We report that individuals with high body fat and low exercise levels have breast inflammation, higher breast aromatase expression, and levels of circulating metabo-inflammatory factors that have been associated with increased breast cancer risk. These findings support interventions to lower adiposity, even among normal weight individuals, to prevent tumor growth.

Effects of obesity on breast aromatase expression and systemic metabo-inflammation in women with BRCA1 or BRCA2 mutations

Obesity is associated with an increased risk of breast cancer in post-menopausal women and decreased risk in pre-menopausal women. Conversely, in BRCA1/2 mutation carriers, pre-menopausal obesity is associated with early-onset breast cancer. Here we show that obese, pre-menopausal BRCA1/2 mutation carriers have increased levels of aromatase and inflammation in the breast, as occurs in post-menopausal women. In a prospective cohort study of 141 women with germline BRCA1 (n = 74) or BRCA2 (n = 67) mutations, leptin, and aromatase expression were higher in the breast tissue of obese versus lean individuals (P < 0.05). Obesity was associated with breast white adipose tissue inflammation, which correlated with breast aromatase levels (P < 0.01). Circulating C-reactive protein, interleukin-6, and leptin positively correlated with body mass index and breast aromatase levels, whereas negative correlations were observed for adiponectin and sex hormone-binding globulin (P < 0.05). These findings could help explain the increased risk of early-onset breast cancer in obese BRCA1/2 mutation carriers.

Genetically Predicted C-Reactive Protein Associated With Postmenopausal Breast Cancer Risk: Interrelation With Estrogen and Cancer Molecular Subtypes Using Mendelian Randomization

Background

Immune-related etiologic pathways that influence breast cancer risk are incompletely understood and may be confounded by lifestyles or reverse causality. Using a Mendelian randomization (MR) approach, we investigated the potential causal relationship between genetically elevated C-reactive protein (CRP) concentrations and primary invasive breast cancer risk in postmenopausal women.

Methods

We used individual-level data obtained from 10,179 women, including 537 who developed breast cancer, from the Women’s Health Initiative Database for Genotypes and Phenotypes Study, which consists of five genome-wide association (GWA) studies. We examined 61 GWA single-nucleotide polymorphisms (SNPs) previously associated with CRP. We employed weighted/penalized weighted–medians and MR gene–environment interactions that allow instruments’ invalidity to some extent and attenuate the heterogeneous estimates of outlying SNPs.

Results

In lifestyle-stratification analyses, genetically elevated CRP decreased risk for breast cancer in exogenous estrogen-only, estrogen + progestin, and past oral contraceptive (OC) users, but only among relatively short-term users (<5 years). Estrogen-only users for ≥5 years had more profound CRP-decreased breast cancer risk in dose–response fashion, whereas past OC users for ≥5 years had CRP-increased cancer risk. Also, genetically predicted CRP was strongly associated with increased risk for hormone-receptor positive or human epidermal growth factor receptor-2 negative breast cancer.

Conclusions

Our findings may provide novel evidence on the immune-related molecular pathways linking to breast cancer risk and suggest potential clinical use of CRP to predict the specific cancer subtypes. Our findings suggest potential interventions targeting CRP–inflammatory markers to reduce breast cancer risk.

Pro-inflammatory cytokine polymorphisms and interactions with dietary alcohol and estrogen, risk factors for invasive breast cancer using a post genome-wide analysis for gene-gene and gene-lifestyle interaction

Molecular and genetic immune-related pathways connected to breast cancer and lifestyles in postmenopausal women are not fully characterized. In this study, we explored the role of pro-inflammatory cytokines such as C-reactive protein (CRP) and interleukin-6 (IL-6) in those pathways at the genome-wide level. With single-nucleotide polymorphisms (SNPs) in the biomarkers and lifestyles together, we further constructed risk profiles to improve predictability for breast cancer. Our earlier genome-wide association gene-environment interaction study used large cohort data from the Women's Health Initiative Database for Genotypes and Phenotypes Study and identified 88 SNPs associated with CRP and IL-6. For this study, we added an additional 68 SNPs from previous GWA studies, and together with 48 selected lifestyles, evaluated for the association with breast cancer risk via a 2-stage multimodal random survival forest and generalized multifactor dimensionality reduction methods. Overall and in obesity strata (by body mass index, waist, waist-to-hip ratio, exercise, and dietary fat intake), we identified the most predictive genetic and lifestyle variables. Two SNPs (SALL1 rs10521222 and HLA-DQA1 rs9271608) and lifestyles, including alcohol intake, lifetime cumulative exposure to estrogen, and overall and visceral obesity, are the most common and strongest predictive markers for breast cancer across the analyses. The risk profile that combined those variables presented their synergistic effect on the increased breast cancer risk in a gene-lifestyle dose-dependent manner. Our study may contribute to improved predictability for breast cancer and suggest potential interventions for the women with the risk genotypes and lifestyles to reduce their breast cancer risk.

Leptin and its receptor are overexpressed in breast cancer tissue of postmenopausal Mexican-Mestizo women with obesity

The aim of this study was to investigate the expression of leptin (LEP) and its receptor (LEPR) in breast cancer tissue of postmenopausal women with different body mass indexes (BMI), as well as the relationship of this expression with the rate of recurrence free survival (RFS). Leptin and LEPR expression, determined by immunohistochemistry, were studied in breast cancer tissues of 154 patients. Qualitative and semi-quantitative analysis of protein expression was performed by the H-Score method, through the ImageJ's IHC Profiler software. Kaplan-Meier survival analysis and log-rank statistic were used to estimate RFS differences. Protein expression of LEP, was significantly higher in women with overweight or with obesity, when compared to women with normal BMI (P = 0.032 and P = 0.013, respectively). We also observed a significantly higher expression of LEPR in breast tumor cells of women with obesity (58.8%), when compared to women with normal BMI (32.7%) (P = 0.007). Five-year survival rate, regarding LEPR expression, was 82.4% when positive and 94% when negative (P = 0.024). In the Cox proportional-hazards regression model, LEPR expression represented a risk factor for disease recurrence after adjustment for confounding factors (HR = 4.67; 95% CI: 1.13-19.31; P = 0.033). In conclusion, postmenopausal women with obesity and breast cancer present higher LEP and LEPR expression in breast tumors, when compared to women with normal BMI. Independently from BMI, women with tumors LEPR positive have worst RFS, when compared to women with tumors LEPR negative.

Chronic inflammation towards cancer incidence: A systematic review and meta-analysis of epidemiological studies

This systematic review and meta-analysis provides epidemiological data on the relationship between chronic inflammation, as measured by inflammatory blood parameters, and cancer incidence. Two independent researchers searched PubMed, Web Of Science and Embase databases until October 2020. In vitro studies, animal studies, studies with chronically-ill subjects or cross-sectional studies were excluded. Quality was assessed with the Newcastle-Ottawa scale. The 59 nested case-control, 6 nested case-cohort and 42 prospective cohort studies considered 119 different inflammatory markers (top three: CRP, fibrinogen and IL6) and 26 cancer types (top five: colorectal, lung, breast, overall and prostate cancer). Nineteen meta-analyses resulted in ten significant positive associations: CRP-breast (OR = 1.23[1.05-1.43];HR = 1.14[1.01-1.28)), CRP-colorectal (OR = 1.34[1.11-1.60]), CRP-lung (HR = 2.03[1.59-2.60]), fibrinogen-lung (OR = 2.56[1.86-3.54]), IL6-lung (OR = 1.41[1.12-1.78]), CRP-ovarian (OR = 1.41[1.10-1.80]), CRP-prostate (HR = 1.09[1.03-1.15]), CRP-overall (HR = 1.35[1.16-1.57]) and fibrinogen-overall (OR = 1.22[1.07-1.39]). Study quality improvements can be done by better verification of inflammatory status (more than one baseline measurement of one parameter), adjusting for important confounders and ensuring long-term follow-up.

Genome-wide Association Analysis of Proinflammatory Cytokines and Gene-lifestyle Interaction for Invasive Breast Cancer Risk: The WHI dbGaP Study

Immune-related etiologic pathways to influence invasive breast cancer risk may interact with lifestyle factors, but the interrelated molecular genetic pathways are incompletely characterized. We used data from the Women's Health Initiative Database for Genotypes and Phenotypes Study including 16,088 postmenopausal women, a population highly susceptible to inflammation, obesity, and increased risk for breast cancer. With 21,784,812 common autosomal single-nucleotide polymorphisms (SNP), we conducted a genome-wide association (GWA) gene-environment interaction (G × E) analysis in six independent GWA Studies for proinflammatory cytokines [IL6 and C-reactive protein (CRP)] and their gene-lifestyle interactions. Subsequently, we tested for the association of the GWA SNPs with breast cancer risk. In women overall and stratified by obesity status (body mass index, waist circumference, and waist-to-hip ratio) and obesity-related lifestyle factors (exercise and high-fat diet), 88 GWA SNPs in 10 loci were associated with proinflammatory cytokines: 3 associated with IL6 (1 index SNP in MAPK1 and 1 independent SNP in DEC1); 85 with CRP (3 index SNPs in CRPP1, CRP, RP11-419N10.5, HNF1A-AS1, HNF1A, and C1q2orf43; and two independent SNPs in APOE and APOC1). Of those, 27 in HNF1A-AS1, HNF1A, and C1q2orf43 displayed significantly increased risk for breast cancer. We found a number of novel top markers for CRP and IL6, which interacted with obesity factors. A substantial proportion of those SNPs' susceptibility influenced breast cancer risk. Our findings may contribute to better understanding of genetic associations between pro-inflammation and cancer and suggest intervention strategies for women who carry the risk genotypes, reducing breast cancer risk. PREVENTION RELEVANCE: The top GWA-SNPs associated with pro-inflammatory biomarkers have implications for breast carcinogenesis by interacting with obesity factors. Our findings may suggest interventions for women who carry the inflammatory-risk genotypes to reduce breast cancer risk.

Effects of major lifestyle factors on breast cancer risk: impact of weight, nutrition, physical activity, alcohol and tobacco

Breast cancer (BC) is the most commonly diagnosed cancer and second most common cause of cancer death in US women. Family history and genetics are well-known BC risk factors, but they only account for 15–20% of BC cases. Therefore, in addition to family history, healthcare providers must consider a woman’s modifiable and nonmodifiable personal risk factors that are associated with an increase in BC risk. The World Cancer Research Fund/American Institute for Cancer Research estimate that 30% of BC cases in the US are preventable. Lifestyle education is imperative given the magnitude of BC occurrence. Evidence supports prevention as an effective, long-term strategy for reducing risk. Healthcare providers are key stakeholders in empowering patients to adopt a healthy lifestyle for primary BC prevention. In this paper, we review the available evidence on modifiable BC risk including weight management, nutrition, physical activity, alcohol and tobacco use and provide strategies to counsel patients on lifestyle modifications.

Hybrid Dietary-Blood Inflammatory Profiles and Postmenopausal Breast Cancer: A Case-Control Study

The carcinogenesis process is associated with inflammation, which can be modified by diet. There is limited evidence regarding the inflammatory status and diet in association with breast cancer (BC). The aim of this study was to investigate the association of hybrid dietary-blood inflammatory profiles (HD-BIPs) with postmenopausal breast cancer occurrence. The case-control study was conducted among 420 women (230 controls, 190 primary BC cases) aged 40–79 years from north-eastern Poland. Blood levels of C-reactive protein (CRP), interleukin-6 (IL-6) and leukocyte count were marked in 129 postmenopausal women (82 controls, 47 cases). The 62-item food frequency questionnaire (FFQ-6) was used to the dietary data collection. Two HD-BIPs were found using the Principal Component Analysis (PCA). The “Pro-healthy/Neutral-inflammatory” profile was characterized by the frequent consumption of wholemeal cereals/coarse groats, legumes, vegetables, fruits, nuts/seeds and fish. The “Unhealthy/Pro-inflammatory” profile was characterized by the frequent consumption of red/processed meats, animal fats, sugar/honey/sweets, refined cereals/fine groats, and an increased concentration of CRP, IL-6 and granulocyte-to-lymphocyte ratio. The lower odds ratio (OR) of breast cancer was associated with the higher adherence to the “Pro-healthy/Neutral-inflammatory” profile (OR = 0.38; 95% Cl: 0.18–0.80; p < 0.01 for the higher level vs. lower level, crude model; OR for one-point score increment: 0.61; 95% Cl: 0.42–0.87; p < 0.01, adjusted model). The higher OR of breast cancer was associated with the higher adherence to the “Unhealthy/Pro-inflammatory” profile (OR = 3.07; 95%Cl: 1.27–7.44; p < 0.05 for the higher level v.s. lower level, adjusted model; OR for one-point score increment: 1.18; 95%Cl: 1.02–1.36; p < 0.05, adjusted model). This study revealed that the consumption of highly processed, high in sugar and animal fat foods should be avoided because this unhealthy diet was positively associated with postmenopausal breast cancer occurrence through its pro-inflammatory potential. Instead, the frequent consumption of low-processed plant foods and fish should be recommended since this pro-healthy diet was inversely associated with the cancer occurrence even though its anti-inflammatory potential has not been confirmed in this study sample.

Adipocytokines visfatin and resistin in breast cancer: Clinical relevance, biological mechanisms, and therapeutic potential

Obesity is one of the major modifiable risk factors in breast cancer, with obese adipose tissue showing a pathological role in breast cancer development and malignancy via the release of secretory factors, such as proinflammatory cytokines and adipocytokines. The current article focuses on visfatin and resistin, two such adipocytokines that have emerged over the last two decades as leading breast cancer promoting factors in obesity. The clinical association of circulating visfatin and resistin with breast cancer and their biological mechanisms are reviewed, in addition to their role in the context of tumor-stromal interactions in the breast cancer microenvironment. Recent findings have unraveled several mediators of visfatin and resistin that are involved in the crosstalk between breast cancer cells and adipose tissue in the breast tumor microenvironment, including growth differentiation factor 15 (GDF15), interleukin 6 (IL-6), and toll-like receptor 4 (TLR4). Finally, current therapeutics targeting visfatin and resistin and their respective pathways are discussed, including future therapeutic strategies such as new drug design or neutralizing peptides that target extracellular visfatin or resistin. These hold promise in the development of novel breast cancer therapies and are of increasing relevance as the prevalence of obesity-related breast cancer increases worldwide.

High-sensitivity C-reactive protein, hemoglobin A1c and breast cancer risk: a nested case-control study from Alberta's Tomorrow Project cohort

PURPOSE

Our aim is to examine the associations between high-sensitivity C-reactive protein (hsCRP) and hemoglobin A1c (HbA1c), common biomarkers of inflammation and insulin resistance, respectively, with breast cancer risk, while adjusting for measures of excess body size.

METHODS

We conducted a nested case-control study within the Alberta's Tomorrow Project cohort (Alberta, Canada) including 197 incident breast cancer cases and 394 matched controls. The sample population included both pre- and postmenopausal women. Serum concentrations of hsCRP and HbA1c were measured from blood samples collected at baseline, along with anthropometric measurements, general health and lifestyle data. Conditional logistic regression was used to evaluate associations between hsCRP, HbA1c, and breast cancer risk adjusted for excess body size (body fat percentage) and other risk factors for breast cancer.

RESULTS

Higher concentrations of hsCRP were associated with elevated breast cancer risk (odds ratio [OR] 1.27; 95% confidence interval [95% CI] 1.03-1.55). The observed associations were unchanged with adjustment for body fat percentage. Higher HbA1c concentrations were not significantly associated with an increased breast cancer risk (OR 1.22; 95% CI 0.17-8.75).

CONCLUSION

These data suggest that hsCRP may be associated with elevated breast cancer risk, independent of excess body size. However, elevated concentrations of HbA1c did not appear to increase breast cancer risk in apparently healthy women.

Mendelian randomisation analysis of circulating adipokines and C-reactive protein on breast cancer risk

Circulating adipokines and C-reactive protein (CRP) have been linked to breast cancer risk in observational epidemiological studies. The causal nature of these associations is unclear because of the susceptibility of conventional observational designs to residual confounding, reverse causation and other forms of bias. Mendelian randomisation (MR) uses genetic variants as proxies for risk factors to strengthen causal inference in observational settings. We performed a MR analysis to evaluate the causal relevance of six previously reported circulating adipokines [adiponectin, hepatocyte growth factor (HGF), interleukin-6, leptin receptor, plasminogen activator inhibitor-1 and resistin] and CRP in risk of overall and oestrogen receptor-stratified breast cancer in up to 122,977 cases and 105,974 controls of European ancestry. Genetic instruments were constructed from single-nucleotide polymorphisms robustly (p < 5 × 10-8 ) associated with risk factors in genome-wide association studies. Colocalisation was performed as a sensitivity analysis to examine whether findings reflected shared causal variants or genomic confounding. In MR analyses, there was evidence for an association of HGF with oestrogen receptor-negative cancer (odds ratio per standard deviation increase: 1.17, 95% confidence interval: 1.01-1.35; p = 0.035) but little evidence for associations of other adipokines or CRP with overall or oestrogen receptor-stratified breast cancer. Colocalisation analysis suggested that the association of HGF with oestrogen receptor-negative breast cancer was unlikely to reflect a causal association. Collectively, these findings do not support an important aetiological role of various adipokines or CRP in overall or oestrogen receptor-specific breast cancer risk.

Aspirin use and risk of breast cancer in African American women

BACKGROUND

Use of aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) has been hypothesized to be associated with reduced risk of breast cancer; however, results of epidemiological studies have been mixed. Few studies have investigated these associations among African American women.

METHODS

To assess the relation of aspirin use to risk of breast cancer in African American women, we conducted a prospective analysis within the Black Women's Health Study, an ongoing nationwide cohort study of 59,000 African American women. On baseline and follow-up questionnaires, women reported regular use of aspirin (defined as use at least 3 days per week) and years of use. During follow-up from 1995 through 2017, 1919 invasive breast cancers occurred, including 1112 ER+, 569 ER-, and 284 triple-negative (TN) tumors. We used age-stratified Cox proportional hazards regression models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for associations of aspirin use with risk of ER+, ER-, and TN breast cancer, adjusted for established breast cancer risk factors.

RESULTS

Overall, the HR for current regular use of aspirin relative to non-use was 0.92 (95% CI 0.81, 1.04). For ER+, ER-, and TN breast cancer, corresponding HRs were 0.98 (0.84, 1.15), 0.81 (0.64, 1.04), and 0.70 (0.49, 0.99), respectively.

CONCLUSIONS

Our findings with regard to ER- and TN breast cancer are consistent with hypothesized inflammatory mechanisms of ER- and TN breast cancer, rather than hormone-dependent pathways. Aspirin may represent a potential opportunity for chemoprevention of ER- and TN breast cancer.

Mendelian randomization analyses of genetically predicted circulating levels of cytokines with risk of breast cancer

To determine whether genetically predicted circulating levels of cytokines are associated with risk of overall breast cancer (BC), estrogen receptor (ER)-positive and ER-negative BC, we conducted two-sample MR analyses using data from the most comprehensive genome-wide association studies (GWAS) on cytokines in 8293 Finnish participants and the largest BC GWAS from the Breast Cancer Association Consortium (BCAC) with totally 122,977 BC cases and 105,974 healthy controls. We systematically screened 41 cytokines (of which 24 cytokines have available instruments) and identified that genetically predicted circulating levels (1-SD increase) of MCP1 (OR: 1.08; 95% CIs: 1.03–1.12; P value: 3.55 × 10⁻⁴), MIP1b (OR: 1.02; 95% CIs: 1.01–1.04; P value: 2.70 × 10⁻³) and IL13 (OR: 1.06; 95% CIs: 1.03–1.10; P value: 3.33 × 10⁻⁴) were significantly associated with increased risk of overall BC, as well as ER-positive BC. In addition, higher levels of MIP1b and IL13 were also significantly associated with increased risk of ER-negative BC. These findings suggest the crucial role of cytokines in BC carcinogenesis and potential of targeting specific inflammatory cytokines for BC prevention.

Inflammatory Biomarkers and Breast Cancer Risk: A Systematic Review of the Evidence and Future Potential for Intervention Research

Measuring systemic chronic inflammatory markers in the blood may be one way of understanding the role of inflammation in breast cancer risk, and might provide an intermediate outcome marker in prevention studies. Here, we present the results of a systematic review of prospective epidemiologic studies that examined associations between systemic inflammatory biomarkers measured in blood and breast cancer risk. From 1 January 2014 to 20 April 2020, we identified 18 unique studies (from 16 publications) that examined the association of systemic inflammatory biomarkers measured in blood with breast cancer risk using prospectively collected epidemiologic data. Only one marker, C-reactive protein, was studied extensively (measured in 13 of the 16 publications), and had some evidence of a positive association with breast cancer risk. Evidence associating other inflammatory biomarkers and more comprehensive panels of markers with the development of breast cancer is limited. Future prospective evidence from expanded panels of systemic blood inflammatory biomarkers is needed to establish strong and independent links with breast cancer risk, along with mechanistic studies to understand inflammatory pathways and demonstrate how breast tissue responds to chronic inflammation. This knowledge could ultimately support the development and evaluation of mechanistically driven interventions to reduce inflammation and prevent breast cancer.

The Relationship Between White Adipose Tissue Inflammation and Overweight/Obesity in Chinese Female Breast Cancer: A Retrospective Study

INTRODUCTION

This study aims to investigate the relationship between breast white adipose tissue (WAT) inflammation and being overweight or obese, menopausal status, and metabolic syndrome-related indicators in breast cancer patients as well as the association between adipocyte size and the severity of WAT inflammation and body mass index (BMI).

METHODS

The crown-like structures (CLS-B) formed by macrophages surrounding dying or dead adipocytes can be used to identify breast WAT inflammation. In this study, breast WAT and fasting blood from 136 Chinese women with breast cancer were collected for analysis. Cluster of differentiation 68 (CD68) immunohistochemical staining was performed to identify CLS-B, and the adipocyte size was measured by hematoxylin and eosin staining.

RESULTS

The results showed that breast WAT inflammation usually occurs in overweight/obese breast cancer patients, and the severity of inflammation is positively correlated with adipocyte hypertrophy. We did not observe a direct association between WAT inflammation and menopausal status. In addition, the presence of WAT inflammation is associated with abnormalities in circulating factors associated with metabolic syndrome such as higher serum lipid, glucose, and C-reactive protein levels.

CONCLUSION

Overweight/obese breast cancer patients may be more prone to breast WAT inflammation and may be associated with abnormalities in circulatory markers associated with metabolic syndrome.

Novel insights into adiponectin action in breast cancer: Evidence of its mechanistic effects mediated by ERα expression

This review describes the multifaceted effects of adiponectin on breast cancer cell signalling, tumour metabolism, and microenvironment. It is largely documented that low adiponectin levels are associated with an increased risk of breast cancer. However, it needs to be still clarified what are the extents of the decrease of local/intra-tumoural adiponectin concentrations, which promote breast tumour malignancy. Most of the anti-proliferative and pro-apoptotic effects induced by adiponectin have been obtained in breast cancer cells not expressing estrogen receptor alpha (ERα). Here, we will highlight recent findings demonstrating the mechanistic effects through which adiponectin is able to fuel genomic and non-genomic estrogen signalling, inhibiting LKB1/AMPK/mTOR/S6K pathway and switching energy balance. Therefore, it emerges that the reduced adiponectin levels in patients with obesity work to sustain tumour growth and progression in ERα-positive breast cancer cells. All this may contribute to remove the misleading paradigm that adiponectin univocally inhibits breast cancer cell growth and progression independently on ERα status. The latter concept, here clearly provided by pre-clinical studies, may have translational relevance adopting adiponectin as a potential therapeutic tool. Indeed, the interfering role of ERα on adiponectin action addresses how a separate assessment of adiponectin treatment needs to be considered in novel therapeutic strategies for ERα-positive and ERα-negative breast cancer.

Circulating obesity-driven biomarkers are associated with risk of clear cell renal cell carcinoma: a two-stage, case-control study

Obesity is one of modifiable risk factors for clear cell renal cell cancer (ccRCC). We aim to identify the association between obesity-driven biomarkers and ccRCC risk. This is a retrospective, two-phase, case-control study involving 682 cases and 733 controls. Obesity-driven biomarkers [gastric inhibitory polypeptide (GIP), C-peptide, insulin, resistin, adipsin, peptide YY, pancreatic polypeptide, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), plasminogen activator inhibitor-1, monocyte chemoattractant protein 1, lipocalin2, leptin, adiponectin] were measured using the Milliplex method. Multivariate logistic regression was used to assess the associations between biomarkers and ccRCC risk. Results revealed that GIP, C-peptide, IL-6 and TNF-α levels were consistently distinct between cases and controls. These markers were significantly associated with ccRCC risk in both phases (except C-peptide). In the combined population, compared with individuals with low levels of the biomarkers, individuals with high level of GIP [odds ratio (OR) = 0.52, 95% confidence interval (CI): 0.40-0.67] had lower risk, whereas individuals with high levels of C-peptide (OR = 1.46, 95% CI: 1.15-1.87), IL-6 (OR = 2.20, 95% CI: 1.50-3.22), TNF-α (OR = 1.90, 95% CI: 1.49-2.43) had significantly higher risk. Stratified analysis showed consistent associations with ccRCC risk in most subgroups (P < 0.05). The risk score based on the IL-6, TNF-α and GIP was positively associated with ccRCC risk in a dose-response manner (P for trend = 2.18E-13). Data from The Cancer Genome Atlas indicate that insulin signaling, IL-6 signaling and TNF-α signaling were enhanced in tumors. Collectively, our study demonstrates the integrative effect of insulin resistance and inflammation in ccRCC development, which may elucidate the basis of association between obesity and carcinogenesis. Further confirmation in prospective cohort studies are warranted for clinical applications in prevention and precision medicine of ccRCC.

A Metabolomics Analysis of Body Mass Index and Postmenopausal Breast Cancer Risk

Background

Elevated body mass index (BMI) is associated with increased risk of postmenopausal breast cancer. The underlying mechanisms, however, remain elusive.

Methods

In a nested case-control study of 621 postmenopausal breast cancer case participants and 621 matched control participants, we measured 617 metabolites in prediagnostic serum. We calculated partial Pearson correlations between metabolites and BMI, and then evaluated BMI-associated metabolites (Bonferroni-corrected α level for 617 statistical tests = P < 8.10 × 10-5) in relation to invasive breast cancer. Odds ratios (ORs) of breast cancer comparing the 90th vs 10th percentile (modeled on a continuous basis) were estimated using conditional logistic regression while controlling for breast cancer risk factors, including BMI. Metabolites with the lowest P values (false discovery rate < 0.2) were mutually adjusted for one another to determine those independently associated with breast cancer risk.

Results

Of 67 BMI-associated metabolites, two were independently associated with invasive breast cancer risk: 16a-hydroxy-DHEA-3-sulfate (OR = 1.65, 95% confidence interval [CI] = 1.22 to 2.22) and 3-methylglutarylcarnitine (OR = 1.67, 95% CI = 1.21 to 2.30). Four metabolites were independently associated with estrogen receptor-positive (ER+) breast cancer risk: 16a-hydroxy-DHEA-3-sulfate (OR = 1.84, 95% CI = 1.27 to 2.67), 3-methylglutarylcarnitine (OR = 1.91, 95% CI = 1.23 to 2.96), allo-isoleucine (OR = 1.76, 95% CI = 1.23 to 2.51), and 2-methylbutyrylcarnitine (OR = 1.89, 95% CI = 1.22 to 2.91). In a model without metabolites, each 5 kg/m2 increase in BMI was associated with a 14% higher risk of breast cancer (OR = 1.14, 95% CI = 1.01 to 1.28), but adding 16a-hydroxy-DHEA-3-sulfate and 3-methylglutarylcarnitine weakened this association (OR = 1.06, 95% CI = 0.93 to 1.20), with the logOR attenuating by 57.6% (95% CI = 21.8% to 100.0+%).

Conclusion

These four metabolites may signal metabolic pathways that contribute to breast carcinogenesis and that underlie the association of BMI with increased postmenopausal breast cancer risk. These findings warrant further replication efforts.

Association of Body Fat and Risk of Breast Cancer in Postmenopausal Women With Normal Body Mass Index: A Secondary Analysis of a Randomized Clinical Trial and Observational Study

Importance

Obesity is associated with an increased risk of breast cancer, including the estrogen receptor (ER)-positive subtype in postmenopausal women. Whether excess adiposity is associated with increased risk in women with a normal body mass index (BMI; calculated as weight in kilograms divided by height in meters squared) is unknown.

Objective

To investigate the association between body fat and breast cancer risk in women with normal BMI.

Design, Setting, and Participants

This ad hoc secondary analysis of the Women's Health Initiative (WHI) clinical trial and observational study cohorts was restricted to postmenopausal participants with a BMI ranging from 18.5 to 24.9. Women aged 50 to 79 years were enrolled from October 1, 1993, through December 31, 1998. Of these, 3460 participants underwent body fat measurement with dual-energy x-ray absorptiometry (DXA) at 3 US designated centers with follow-up. At a median follow-up of 16 years (range, 9-20 years), 182 incident breast cancers had been ascertained, and 146 were ER positive. Follow-up was complete on September 30, 2016, and data from October 1, 1993, through September 30, 2016, was analyzed August 2, 2017, through August 21, 2018.

Main Outcomes and Measures

Body fat levels were measured at baseline and years 1, 3, 6, and 9 using DXA. Information on demographic data, medical history, and lifestyle factors was collected at baseline. Invasive breast cancers were confirmed via central review of medical records by physician adjudicators. Blood analyte levels were measured in subsets of participants.

Results

Among the 3460 women included in the analysis (mean [SD] age, 63.6 [7.6] years), multivariable-adjusted hazard ratios for the risk of invasive breast cancer were 1.89 (95% CI, 1.21-2.95) for the highest quartile of whole-body fat and 1.88 (95% CI, 1.18-2.98) for the highest quartile of trunk fat mass. The corresponding adjusted hazard ratios for ER-positive breast cancer were 2.21 (95% CI, 1.23-3.67) and 1.98 (95% CI, 1.18-3.31), respectively. Similar positive associations were observed for serial DXA measurements in time-dependent covariate analyses. Circulating levels of insulin, C-reactive protein, interleukin 6, leptin, and triglycerides were higher, whereas levels of high-density lipoprotein cholesterol and sex hormone-binding globulin were lower in those in the uppermost vs lowest quartiles of trunk fat mass.

Conclusions and Relevance

In postmenopausal women with normal BMI, relatively high body fat levels were associated with an elevated risk of invasive breast cancer and altered levels of circulating metabolic and inflammatory factors. Normal BMI categorization may be an inadequate proxy for the risk of breast cancer in postmenopausal women.

Trial Registration

ClinicalTrials.gov identifier: NCT00000611.

Association of serum leptin with breast cancer: A meta-analysis

BACKGROUND

Accumulating evidence has demonstrated that leptin is associated to the tumorigenesis and progression of breast cancer (BC). However, these studies remain inconsistent. Thus, a meta-analysis was conducted to investigate the role of leptin in the patients with BC.

METHOD

A systematic search in PubMed, Embase, ISI Web of Science, and Chinese National Knowledge Infrastructure (CNKI) databases was conducted up to September 1, 2017. The standardized mean difference (SMD) with 95% confidence interval (CI) was applied to pool the effect size. A funnel plot and Egger test were used to evaluate publication bias.

RESULTS

Finally, 43 eligible studies were included in the current meta-analysis. Overall, serum leptin levels in BC cases were significantly higher compared with the controls (SMD = 0.61, P <.0001). When subgroup analyses were restricted to ethnicity and menstrual status, higher serum leptin concentration was also detected in patients with BC. Moreover, BC cases with body mass index (BMI) >25 indicated significantly higher serum leptin levels (SMD = 1.48, P = .034). Furthermore, the BC cases with lymph node metastases showed significantly higher serum leptin concentration (SMD = 0.53, P = .015).

CONCLUSION

The present meta-analysis suggests that the serum leptin may profiles as a pivotal role in the pathogenesis and metastasis of BC. In addition, leptin will provide useful information for a therapeutic target to treat BC.

Association of serum adiponectin with breast cancer: A meta-analysis of 27 case-control studies

BACKGROUND

Emerging published studies have indicated that adiponectin is involved in tumorigenesis of breast cancer. However, the results of available studies were inconsistent. The aim of this updated meta-analysis was to assess the association of adiponectin with breast cancer.

MATERIALS AND METHODS

PubMed, EMBASE, Wanfang databases, and the China National Knowledge Infrastructure (CNKI) were systematically searched from inception to June 2018. The mean difference (MD) with 95% confidence interval (CI) were estimated and pooled to investigate the effect sizes.

RESULTS

Twenty-seven eligible articles that met the study criteria were included in the current meta-analysis. Overall, there was an evident inverse association between serum adiponectin levels and breast cancer (MD = -0.29, 95%CI = (-0.38, -0.21), P < .001). Asian subgroup showed a significant negative association between serum adiponectin concentrations and breast cancer in subgroup analysis by ethnicity (MD = -2.19, 95%CI = (-3.45, -0.94), P < .001). However, no statistical significance was found in Caucasian subgroup (MD = -0.65, 95%CI = (-1.47, 0.17), P = 0.12). Additionally, a further subgroup analysis of Asian stratified by menopausal status showed higher concentrations of adiponectin in healthy control group, whether they were premenopausal (MD = -0.85, 95%CI = (-1.50, -0.19), P = .01) or postmenopausal (MD = -2.17, 95%CI = (-4.17, -0.18), P = .03). No significant difference was observed concerning the association between serum adiponectin and breast cancer metastasis (MD = -1.56, 95%CI = (-4.90, 1.78), P = .36).

CONCLUSION

The current meta-analysis suggests that the serum adiponectin may be inversely associated with breast cancer. Decreased serum adiponectin levels in premenopausal women may also be inversely associated with breast cancer risk other than postmenopausal status. In addition, low serum adiponectin levels in Asian women were more likely to be associated with breast cancer risk than Caucasian women.

Nutrition, Cancer and Personalized Medicine

Cancer is a complex group of diseases where different signaling pathways have been found to be deregulated, mainly related to cell proliferation, angiogenesis, metastasis, evasion of apoptosis and insensitivity to anti-growth sings among others. Diet plays a fundamental role in the treatment of the oncological patients, we must be aware that food can interact with certain types of cancer therapy. On the other hand, cancer therapies sometimes affect the patient's sense of smell, taste, appetite, gastric capacity or nutrient absorption, which often results in malnutrition due to the lack of essential nutriments. In this chapter we will review the effect of different metabolic disorders in cancer and mechanisms of action of some phytochemicals found in different foods like resveratrol, EGCG, curcumin and lycopene.

Linking obesity-induced leptin-signaling pathways to common endocrine-related cancers in women

Obesity is related to many major diseases and cancers. Women have higher rates of obesity and obesity is linked to commonly occurring cancers in women. However, there is a lack of knowledge of the unique mechanism(s) involved in each type of cancer. The objective of this review is to highlight the need for novel experimental approaches and a better understanding of the common and unique pathways to resolve controversies regarding the role of obesity in cancer. In women, there is a link between hormones and obesity-associated genes in cancer development. Leptin is an obesity-associated gene that has been studied extensively in cancers; however, whether the defect is in the leptin gene or in its signaling pathways remains unclear. Both leptin and its receptor have been positively correlated with cancer progression in some endocrine-related cancers in women. This review offers an up-to-date and cohesive review of both upstream and downstream pathways of leptin signaling in cancer and a comprehensive picture of cancer pathogenesis in light of current evidence of leptin effects in several major types of cancer. This work is intended to aid in the design of better therapeutic strategies for obese/overweight women with cancer.