Association of breast cancer and obesity in a homogeneous population from Spain

A review on interplay between obesity, lipoprotein profile and nutrigenetics with selected candidate marker genes of type 2 diabetes mellitus

BACKGROUND

Type 2 diabetes mellitus, a rapidly growing epidemic, and its frequently related complications demand global attention. The two factors commonly attributed to the epidemic are genetic factors and environmental factors. Studies indicate that the genetic makeup at an individual level and the environmental aspects influence the occurrence of the disease. However, there is insufficiency in understanding the mechanisms through which the gene mutations and environmental components individually lead to T2DM. Also, discrepancies have often been noted in the association of gene variants and type 2 diabetes when the gene factor is examined as a sole attribute to the disease.

STUDY

In this review initially, we have focused on the proposed ways through which CAPN10, FABP2, GLUT2, TCF7L2, and ENPP1 variants lead to T2DM along with the inconsistencies observed in the gene-disease association. The article also emphasizes on obesity, lipoprotein profile, and nutrition as environmental factors and how they lead to T2DM. Finally, the main objective is explored, the environment-gene-disease association i.e. the influence of each environmental factor on the aforementioned specific gene-T2DM relationship to understand if the disease-causing capability of the gene variants is exacerbated by environmental influences.

CONCLUSION

We found that environmental factors may influence the gene-disease relationship. Reciprocally, the genetic factors may alter the environment-disease relationship. To precisely conclude that the two factors act synergistically to lead to T2DM, more attention has to be paid to the combined influence of the genetic variants and environmental factors on T2DM occurrence instead of studying the influence of the factors separately.

ZNF577 Methylation Levels in Leukocytes From Women With Breast Cancer Is Modulated by Adiposity, Menopausal State, and the Mediterranean Diet

The methylation levels of ZNF577 in breast tumors has been previously identified as a possible epigenetic mark of breast cancer associated with obesity. The aim of the current study was to investigate differences in methylation levels of ZNF577 depending on obesity, menopausal state and dietary pattern in blood leukocytes, a non-invasive sample. The methylation levels of ZNF577 of two CpG sites (CpGs) located in promoter and island previously identified as differentially methylated according to adiposity and menopausal state by 450 k array (cg10635122, cg03562414) were evaluated by pyrosequencing in DNA from the blood leukocytes of breast cancer patients [n = 90; n = 64 (71.1%) overweight/obesity and n = 26 (28.9%) normal-weight] and paired tumor tissue biopsies (n = 8 breast cancer patients with obesity; n = 3/5 premenopausal/postmenopausal women). Differences in methylation levels were evaluated at each CpGs individually and at the mean of the two evaluated CpGs. Adherence to the Mediterranean diet was evaluated using the MEDAS-validated questionnaire, and the consumption of food groups of interest was also evaluated using the recommended intakes of the Sociedad Española de Nutricion Comunitaria. The methylation levels of ZNF577 were correlated between paired leukocytes and breast tumor biopsies (r = 0.62; p = 0.001). Moreover, higher methylation was found in leukocytes from patients with obesity (p = 0.002) and postmenopausal patients (p = 0.022) than patients with normal-weight or premenopausal, respectively. After adjusting for the body mass index and age, higher levels of ZNF577 methylation were also found in women with greater adherence to the Mediterranean diet (p = 0.017) or specific foods. Relevantly, the methylation levels of ZNF577 showed a good ability for fish consumption detection [area under the ROC curve (AUC) = 0.72; p = 0.016]. In conclusion, the association between methylation of ZNF577 and adiposity, menopausal state, and adherence to the Mediterranean diet can be detected in the blood leukocytes. The results guarantee the need of performing further studies in longer longitudinal cohorts in order to elucidate the role of ZNF577 methylation in the association between breast cancer, adiposity and dietary patterns.

Comparison of hematological parameters, iron levels, and oxidative stress in women with and without breast cancer: A case- control study

Background: Iron is one of the nutrients that has recently received considerable attention because of its dual role in the incidence of breast cancer. The present study aimed at comparing hematological parameters, iron levels, and oxidative stress in women with and without breast cancer. Methods: The participants in this case-control study were 55 women, of whom 26 were new cases of breast cancer (confirmed by biopsy) as the case, and 29 without cancer (confirmed by mammography) as the control group. All participants underwent blood testing for complete blood count (CBC (free iron, ferritin, total iron binding capacity) TIBC (2, 2-diphenyl-1-picrylhydrazyl (DPPH), and Malondialdehyde (MDA). Results: The mean±SD age of the participants was 44.25±9.82 years, and there was no significant difference between groups. Also, no statistically significant difference was found between the 2 groups in variables, except the mean corpuscular volume of red cells (MCV), mean corpuscular hemoglobin concentration (MCHC), and mean cell hemoglobin (MCH). The use of iron supplements was significantly higher in the control than in the case group (p= 0. 01), with an odds ratio of 0.19% (95% CI: 0.45-0.7). The mean serum DPPH was significantly higher in the control than in the case group (p= 0. 006), but comparison of serum MDA showed no significant difference between the 2 groups. Conclusion: Iron deficiency anemia was greater in patients with breast cancer than in those without it. Moreover, iron supplementation appears to have a protective effect against breast cancer incidence. In addition, serum DPPH, as a total antioxidant index, was significantly higher in the control group.

Body mass index and survival in women with breast cancer-systematic literature review and meta-analysis of 82 follow-up studies

BACKGROUND

Positive association between obesity and survival after breast cancer was demonstrated in previous meta-analyses of published data, but only the results for the comparison of obese versus non-obese was summarised.

METHODS

We systematically searched in MEDLINE and EMBASE for follow-up studies of breast cancer survivors with body mass index (BMI) before and after diagnosis, and total and cause-specific mortality until June 2013, as part of the World Cancer Research Fund Continuous Update Project. Random-effects meta-analyses were conducted to explore the magnitude and the shape of the associations.

RESULTS

Eighty-two studies, including 213 075 breast cancer survivors with 41 477 deaths (23 182 from breast cancer) were identified. For BMI before diagnosis, compared with normal weight women, the summary relative risks (RRs) of total mortality were 1.41 [95% confidence interval (CI) 1.29-1.53] for obese (BMI >30.0), 1.07 (95 CI 1.02-1.12) for overweight (BMI 25.0-<30.0) and 1.10 (95% CI 0.92-1.31) for underweight (BMI <18.5) women. For obese women, the summary RRs were 1.75 (95% CI 1.26-2.41) for pre-menopausal and 1.34 (95% CI 1.18-1.53) for post-menopausal breast cancer. For each 5 kg/m(2) increment of BMI before, <12 months after, and ≥12 months after diagnosis, increased risks of 17%, 11%, and 8% for total mortality, and 18%, 14%, and 29% for breast cancer mortality were observed, respectively.

CONCLUSIONS

Obesity is associated with poorer overall and breast cancer survival in pre- and post-menopausal breast cancer, regardless of when BMI is ascertained. Being overweight is also related to a higher risk of mortality. Randomised clinical trials are needed to test interventions for weight loss and maintenance on survival in women with breast cancer.