Endogenous hormones, inflammation, and body size in premenopausal Mexican women: results from the Mexican Teachers' Cohort (MTC, ESMaestras)

Biomarkers of mammographic density in premenopausal women

BACKGROUND

While mammographic density is one of the strongest risk factors for breast cancer, little is known about its determinants, especially in young women. We applied targeted metabolomics to identify circulating metabolites specifically associated with mammographic density in premenopausal women. Then, we aimed to identify potential correlates of these biomarkers to guide future research on potential modifiable determinants of mammographic density.

METHODS

A total of 132 metabolites (acylcarnitines, amino acids, biogenic amines, glycerophospholipids, sphingolipids, hexose) were measured by tandem liquid chromatography/mass spectrometry in plasma samples from 573 premenopausal participants in the Mexican Teachers' Cohort. Associations between metabolites and percent mammographic density were assessed using linear regression models, adjusting for breast cancer risk factors and accounting for multiple tests. Mean concentrations of metabolites associated with percent mammographic density were estimated across levels of several lifestyle and metabolic factors.

RESULTS

Sphingomyelin (SM) C16:1 and phosphatidylcholine (PC) ae C30:2 were inversely associated with percent mammographic density after correction for multiple tests. Linear trends with percent mammographic density were observed for SM C16:1 only in women with body mass index (BMI) below the median (27.4) and for PC ae C30:2 in women with a BMI over the median. SM C16:1 and PC ae C30:2 concentrations were positively associated with cholesterol (total and HDL) and inversely associated with number of metabolic syndrome components.

CONCLUSIONS

We identified new biomarkers associated with mammographic density in young women. The association of these biomarkers with mammographic density and metabolic parameters may provide new perspectives to support future preventive actions for breast cancer.

Associations of serum CRP levels with demographics, health behaviors, and risk of cancer among the Mexican American Mano A Mano Cohort

C-Reactive protein (CRP) is a well-known inflammatory marker, and elevated CRP levels has been reported to be associated with the risk of various cancers. To date, no study has investigated the association between elevated CRP and incidents of cancer among Mexican Americans. In the current prospective cohort study, we measured pre-diagnostic CRP levels in serum samples and evaluated their relationships with demographic characteristics and health behaviors associated with cancer risk among 2753 Mexican Americans selected from the Mano-A-Mano Mexican American Cohort Study. At baseline, median levels of serum CRP significantly differed by demographics (sex, age category, marital status, and education levels) and health behaviors (cigarette smoking status, alcohol drinking status, BMI category, and physical activity levels). In the multivariable analysis, the study participants who were women, older, never drinking alcohol, overweight or obese, and physically inactive had increased likelihood of having high CRP levels (≥ median levels among all study participants) compared to their counterparts. A total of 177 cancer cases were identified during the follow-up with a median follow-up time of 127 months. In the quartile analysis, study participants in the 4^th quartile with highest CRP levels had significantly 1.88 fold increased risk of cancer (hazard ratio (HR) = 1.88, 95%CI: 1.12, 3.13) compared to those in the 1^st quartile with lowest CRP levels. The association was further confirmed in analyses using clinical CRP levels. In summary, our findings suggested that serum CRP levels have potential to serve as a predictive marker of cancer risk in Mexican Americans.

Circulating leptin and adiponectin, and breast density in premenopausal Mexican women: the Mexican Teachers' Cohort

PURPOSE

Leptin and adiponectin are produced by the adipose tissue. Mammographic density (MD) is one of the strongest predictors of breast cancer (BC) and is highly influenced by adiposity. How the interplay between MD, obesity, and obesity-related biomarkers influences BC risk, however, is still unknown, especially in premenopausal women, where adiposity seems to be protective for BC. The aim of the present study was to explore the association between circulating leptin, adiponectin, and their ratio, with MD in Mexican premenopausal women who are part of the large Mexican Teachers' Cohort (MTC).

METHODS

A subsample of 2,084 women from the MTC participated in a clinical evaluation. Of them, 574 premenopausal women were randomly selected, from four MD strata. Serum leptin and adiponectin concentrations were measured by immunoassays. Multivariate regression analyses were performed to compare means of MD by quartiles of adipokines and their ratio.

RESULTS

High leptin and leptin/adiponectin ratio levels were significantly associated with lower percentage MD and higher absolute and non-absolute dense tissue areas. High adiponectin levels were significantly associated with lower absolute dense and non-dense tissue areas, but not with percentage MD. After adjustment for BMI, only the associations between percentage MD and absolute non-dense tissue area with leptin remained statistically significant.

CONCLUSIONS

Leptin, adiponectin, and their ratio were associated with MD; however, only the positive association with leptin seemed to be independent from overall obesity.