Insulin Resistance and Breast Carcinogenesis: A Cross-Sectional Study Among Iranian Women with Breast Mass

Dietary Insulin Index and Insulin Load in Relation to Breast Cancer: Findings from a Case-Control Study

BACKGROUND

No data are available on the association between dietary insulin index (DII) and dietary insulin load (DIL) and the risk of breast cancer (BC).

PATIENTS AND METHODS

This hospital-based case-control study enrolled 150 newly diagnosed cases of BC and 150 age-matched controls. All cases were patients with pathologically confirmed BC, with no history of any type of other pathologically confirmed cancers. Controls were selected from visitors, relatives, and friends of non-cancer patients in other wards who had no family relationships with the cases. We assessed the dietary intakes of study participants using a validated 147-item semiquantitative food frequency questionnaire. DII and DIL were obtained from previously published data.

RESULTS

A significant positive association was found between DII and BC (odds ratio [OR], 1.82; 95% confidence interval [CI], 1.02-3.25), such that after considering energy intake and age, participants in the highest tertile of DII had 1.86 times greater risk of BC than those in the lowest tertile (OR, 1.86; 95% CI, 1.03-3.35). However, this association became non-significant after controlling for further potential risk factors (OR, 3.26; 95% CI, 0.9-11.7). Furthermore, we observed a significant positive association between DIL and BC (OR, 1.9; 95% CI, 1.06-3.40). The association remained significant even after controlling for age and energy intake. Further controlling for other potential confounders resulted in the disappearance of the association (OR, 3.06; 95% CI, 0.87-10.6).

CONCLUSION

Adherence to a diet with high DII and DIL was not associated with odds of BC after controlling for potential confounders.

Anthropometric, metabolic and molecular determinants of human epidermal growth factor receptor 2 expression in luminal B breast cancer

Genomic and trascriptomic profiling has recently contributed details to the characterization of luminal B breast cancer. We explored the contribution of anthropometric, metabolic, and molecular determinants to the multifaceted heterogeneity of this breast cancer subtype, with a specific focus on the association between body mass index (BMI), pre-treatment fasting glucose, hormone receptors, and expression of human epidermal growth factor receptor 2 (HER2). Extensively annotated specimens were obtained from 154 women with luminal B breast cancer diagnosed at two Italian comprehensive cancer centres. Participants' characteristics were descriptively analyzed overall and by HER2 status (positive vs. negative). BMI (<25 vs ≥25), pre-treatment fasting glucose (<median value of 94 mg/dl vs. ≥94) and percentage of hormone receptors were tested for association with HER2 expression in regression models. In univariate models, BMI, fasting glucose and, at a lesser extent, percentage of estrogen receptors (ER) were significantly and inversely associated with HER2 expression (OR: 0.32, 95% CI: 0.16-0.66; 0.43, 0.23-0.82; 0.96, 0.94-0.97, respectively). The multivariate models confirmed the protective role of BMI and ER on HER2 expression, with luminal B HER2 positive patients being significantly less frequent among women within the highest category of BMI and percentage expression of ER compared with their counterparts (OR: 0.22, 95% CI: 0.09-0.53; 0.95, 0.93-0.97). In conclusions, BMI and percentage of ER representation are inversely associated with HER2 expression in luminal B breast cancers. Upon confirmatory findings, this might help identify patient subgroups who may best benefit from the use of interventions targeting insulin resistance in well depicted breast cancer scenarios.

Association between insulin resistance and breast carcinoma: a systematic review and meta-analysis

Objective

This study was undertaken to evaluate the association between components defining insulin resistance and breast cancer in women.

Study Design

We conducted a systematic review of four databases (PubMed-Medline, EMBASE, Web of Science, and Scopus) for observational studies evaluating components defining insulin resistance in women with and without breast cancer. A meta-analysis of the association between insulin resistance components and breast cancer was performed using random effects models.

Results

Twenty-two studies (n = 33,405) were selected. Fasting insulin levels were not different between women with and without breast cancer (standardized mean difference, SMD −0.03, 95%CI −0.32 to 0.27; p = 0.9). Similarly, non-fasting/fasting C-peptide levels were not different between the two groups (mean difference, MD 0.07, −0.21 to 0.34; p = 0.6). Using individual odds ratios (ORs) adjusted at least for age, there was no higher risk of breast cancer when upper quartiles were compared with the lowest quartile (Q1) of fasting insulin levels (OR _{Q2 vs. Q1} 0.96, 0.71 to 1.28; OR _{Q3 vs. Q1} 1.22, 0.91 to 1.64; OR _{Q4 vs. Q1} 0.98, 0.70 to 1.38). Likewise, there were no differences for quartiles of non-fasting/fasting C-peptide levels (OR _{Q2 vs. Q1} 1.12, 0.91 to 1.37; OR _{Q3 vs. Q1} 1.20, 0.91 to 1.59; OR _{Q4 vs. Q1} 1.40, 1.03 to 1.92). Homeostatic model assessment (HOMA-IR) levels in breast cancer patients were significantly higher than in people without breast cancer (MD 0.22, 0.13 to 0.31, p<0.00001).

Conclusions

Higher levels of fasting insulin or non-fasting/fasting C-peptide are not associated with breast cancer in women. HOMA-IR levels are slightly higher in women with breast cancer.

Serum insulin and C-peptide concentration and breast cancer: a meta-analysis

PURPOSE

Chronic hyperinsulinemia may play a role in breast cancer etiology. We performed a meta-analysis examining whether serum concentrations of insulin and C-peptide are associated with increased breast cancer risk.

METHODS

We restricted our analyses to prospective studies. After a systematic literature search, we computed summary relative risks (SRRs) and 95 % confidence intervals (95 % CIs) using random effect models applied to the relative risk associated with the highest versus lowest quantile of serum concentrations. We also graphically examined results in order to identify whether dose-response relationships were present.

RESULTS

Six articles including 1,890 cases were retrieved for serum insulin levels and five for serum C-peptide levels including 1,759 cases. SRR and 95 % CI were 1.08 (0.66-1.78) for insulin and 1.04 (0.77-1.41) for C-peptide. Heterogeneity of results between studies was high for insulin and inexistent for C-peptide. Restricting the analysis to women diagnosed with breast cancer before or after menopause did not alter results. In insulin studies, SRR computed from relative risks not adjusted for body mass index (and other risk factors) was 1.22 (0.91-1.63). The SRR fell to 1.02 (0.53-1.97) in studies that adjusted for body mass index and other factors. Similar drops occurred in C-peptide studies, from 1.11 (0.87-1.41) to 1.06 (0.70-1.61). No consistent dose-response relationship was apparent in either pre- or post-menopausal cancers.

CONCLUSIONS

Our meta-analysis of observational studies found no evidence of an association between serum insulin or C-peptide concentrations and breast cancer risk. Increased risk found by some studies may have been due to inadequate control for adiposity.

Metabolic diseases and cancer risk

PURPOSE OF REVIEW

Metabolic disease and cancer are two of the leading causes of death worldwide. This review focuses on the potential increased relative risk for the development of cancer in a population with a rapidly increasing incidence of metabolic disturbances.

RECENT FINDINGS

A large number of recent epidemiological and prospective studies link metabolic syndrome-associated diseases to an increased risk for development of, as well as mortality from, several types of cancer. In patients diagnosed with metabolic disorders, the incidence of gastrointestinal, glandular and reproductive tract cancers is significantly higher compared to the general population. In line with that, hyperglycemia has recently been shown to be an independent risk factor for overall cancer incidence.

SUMMARY

Disorders connected to the metabolic syndrome have been shown to have profound impacts on the incidence and progression of cancer. Continued efforts to make lifestyle interventions, such as weight loss and increased physical activity in the general population, are clearly warranted as a contribution to efforts aimed at decreasing the development of and mortality from cancer. Progression in this field requires a better understanding of the underlying mechanisms behind the cancer-promoting effects associated with disturbed energy balance.