Aging involves complex biological changes that affect disease susceptibility and aging trajectories. Although females typically live longer than males, they have a higher susceptibility to diseases like Alzheimer\'s, speculated to be influenced by menopause, and reduced ovarian hormone production. Understanding sex-specific differences is crucial for personalized medical interventions and gender equality in health. Our study aims to elucidate sex differences in regional cerebellar structure and connectivity during normal aging by investigating both structural and functional connectivity variations, with a focus on investigating these differences in the context of sex-steroid hormones. The study included 138 participants (mean age = 57(13.3) years, age range = 35-86 years, 54% women). The cohort was divided into three groups: 38 early middle-aged individuals (EMA) (mean age = 41(4.7) years), 48 late middle-aged individuals (LMA) (mean age = 58(4) years), and 42 older adults (OA) (mean age = 72(6.3) years). All participants underwent MRI scans, and saliva samples were collected for sex-steroid hormone quantification (17β-estradiol (E), progesterone (P), and testosterone (T)). We found less connectivity in females between Lobule I-IV and the cuneus, and greater connectivity in females between Crus I, Crus II, and the precuneus with increased age. Higher 17β-estradiol levels were linked to greater connectivity in Crus I and Crus II cerebellar subregions. Analyzing all participants together, testosterone was associated with both higher and lower connectivity in Lobule I-IV and Crus I, respectively, while higher progesterone levels were linked to lower connectivity in females. Structural differences were observed, with EMA males having larger volumes compared to LMA and OA groups, particularly in the right I-IV, right Crus I, right V, and right VI. EMA females showed higher volumes in the right lobules V and VI. These results highlight the significant role of sex hormones in modulating cerebellar connectivity and structure across adulthood, emphasizing the need to consider sex and hormonal status in neuroimaging studies to better understand age-related cognitive decline and neurological disorders.

OBJECTIVE: Sex-steroid hormones are associated with postmenopausal breast cancer but potential confounding from other biological pathways is rarely considered. We estimated risk ratios for sex-steroid hormone biomarkers in relation to postmenopausal estrogen receptor (ER)-positive breast cancer, while accounting for biomarkers from insulin/insulin-like growth factor-signaling and inflammatory pathways.
METHODS: This analysis included 1208 women from a case-cohort study of postmenopausal breast cancer within the Melbourne Collaborative Cohort Study. Weighted Poisson regression with a robust variance estimator was used to estimate risk ratios (RRs) and 95% confidence intervals (CIs) of postmenopausal ER-positive breast cancer, per doubling plasma concentration of progesterone, estrogens, androgens, and sex-hormone binding globulin (SHBG). Analyses included sociodemographic and lifestyle confounders, and other biomarkers identified as potential confounders.
RESULTS: Increased risks of postmenopausal ER-positive breast cancer were observed per doubling plasma concentration of progesterone (RR: 1.22, 95% CI 1.03 to 1.44), androstenedione (RR 1.20, 95% CI 0.99 to 1.45), dehydroepiandrosterone (RR: 1.15, 95% CI 1.00 to 1.34), total testosterone (RR: 1.11, 95% CI 0.96 to 1.29), free testosterone (RR: 1.12, 95% CI 0.98 to 1.28), estrone (RR 1.21, 95% CI 0.99 to 1.48), total estradiol (RR 1.19, 95% CI 1.02 to 1.39) and free estradiol (RR 1.22, 95% CI 1.05 to 1.41). A possible decreased risk was observed for SHBG (RR 0.83, 95% CI 0.66 to 1.05).
CONCLUSIONS: Progesterone, estrogens and androgens likely increase postmenopausal ER-positive breast cancer risk, whereas SHBG may decrease risk. These findings strengthen the causal evidence surrounding the sex-hormone-driven nature of postmenopausal breast cancer.

Estrogen and progesterone levels undergo changes throughout the menstrual cycle. Existing literature regarding the effect of menstrual phases on cardiovascular and autonomic regulation during central hypovolemia is contradictory.
This study aims to explore the influence of menstrual phases on cardiovascular and autonomic responses in both resting and during the central hypovolemia induced by lower body negative pressure (LBNP). This is a companion paper, in which data across the menstrual phases from healthy young females, whose results are reported in Shankwar et al. (2023), were further analysed.
The study protocol consisted of three phases: (1) 30 min of supine rest; (2) 16 min of four LBNP levels; and (3) 5 min of supine recovery. Hemodynamic and autonomic responses (assessed via heart rate variability, HRV) were measured before-, during-, and after-LBNP application using Task Force Monitor® (CNSystems, Graz, Austria). Blood was also collected to measure estrogen and progesterone levels.
In this companion paper, we have exclusively assessed 14 females from the previous study (Shankwar et al., 2023): 8 in the follicular phase of the menstrual cycle (mean age 23.38 ± 3.58 years, height 166.00 ± 5.78 cm, weight 57.63 ± 5.39 kg and BMI of 20.92 ± 1.96 25 kg/m2) and 6 in the luteal phase (mean age 22.17 ± 1.33 years, height 169.83 ± 5.53 cm, weight 62.00 ± 7.54 kg and BMI of 21.45 ± 2.63 kg/m2). Baseline estrogen levels were significantly different from the follicular phase as compared to the luteal phase: (33.59 pg/ml, 108.02 pg/ml, respectively, p < 0.01). Resting hemodynamic variables showed no difference across the menstrual phases. However, females in the follicular phase showed significantly lower resting values of low-frequency (LF) band power (41.38 ± 11.75 n.u. and 58.47 ± 14.37 n.u., p = 0.01), but higher resting values of high frequency (HF) band power (58.62 ± 11.75 n.u. and 41.53 ± 14.37 n.u., p = 0.01), as compared to females in the luteal phase. During hypovolemia, the LF and HF band powers changed only in the follicular phase F(1, 7) = 77.34, p < 0.0001 and F(1, 7) = 520.06, p < 0.0001, respectively.
The menstrual phase had an influence on resting autonomic variables, with higher sympathetic activity being observed during the luteal phase. Central hypovolemia leads to increased cardiovascular and autonomic responses, particularly during the luteal phase of the menstrual cycle, likely due to higher estrogen levels and increased sympathetic activity.

UNASSIGNED: Sex-steroid hormones are associated with postmenopausal breast cancer but potential confounding from other biological pathways is rarely considered. We estimated risk ratios for sex-steroid hormone biomarkers in relation to postmenopausal estrogen receptor (ER)-positive breast cancer, while accounting for biomarkers from insulin/insulin-like growth factor-signaling and inflammatory pathways.
UNASSIGNED: This analysis included 1,208 women from a case-cohort study of postmenopausal breast cancer within the Melbourne Collaborative Cohort Study. Weighted Poisson regression with a robust variance estimator was used to estimate risk ratios (RRs) and 95% confidence intervals (CIs) of postmenopausal ER-positive breast cancer, per doubling plasma concentration of progesterone, estrogens, androgens, and sex hormone binding globulin (SHBG). Analyses included sociodemographic and lifestyle confounders, and other biomarkers identified as potential confounders.
UNASSIGNED: Increased risks of postmenopausal ER-positive breast cancer were observed per doubling plasma concentration of progesterone (RR: 1.22, 95% CI: 1.03 to 1.44), androstenedione (RR: 1.20, 95% CI: 0.99 to 1.45), dehydroepiandrosterone (RR: 1.15, 95% CI: 1.00 to 1.34), total testosterone (RR: 1.11, 95% CI: 0.96 to 1.29), free testosterone (RR: 1.12, 95% CI: 0.98 to 1.28), estrone (RR: 1.21, 95% CI: 0.99 to 1.48), total estradiol (RR: 1.19, 95% CI: 1.02 to 1.39) and free estradiol (RR: 1.22, 95% CI: 1.05 to 1.41). A possible decreased risk was observed for SHBG (RR: 0.83, 95% CI: 0.66 to 1.05).
UNASSIGNED: Progesterone, estrogens and androgens likely increase postmenopausal ER-positive breast cancer risk, whereas SHBG may decrease risk. These findings strengthen the causal evidence surrounding the sex hormone-driven nature of postmenopausal breast cancer.

Mechanisms underlying adiposity-colorectal cancer (CRC) association are incompletely understood. Using UK Biobank data, we investigated the role of C-reactive protein (CRP), hemoglobin-A1c (HbA1c) and (jointly) sex hormone-binding globulin (SHBG) and testosterone, in explaining this association. Total effect of obesity versus normal-weight (based on waist circumference, body mass index, waist-hip ratio) on CRC risk was decomposed into natural direct (NDE) and indirect (NIE) effects using sequential mediation analysis. After a median follow-up of 7.1 years, 2070 incident CRC cases (men = 1,280; postmenopausal women = 790) were recorded. For men, the adjusted risk ratio (RR) for waist circumference (≥102 vs. ≤94 cm) was 1.37 (95% confidence interval [CI], 1.19-1.58). The RRsNIE were 1.08 (95% CI: 1.01-1.16) through all biomarkers, 1.06 (95% CI: 1.01-1.11) through pathways influenced by CRP, 0.99 (95% CI: 0.97-1.01) through HbA1c beyond (the potential influence of) CRP and 1.03 (95% CI: 0.99-1.08) through SHBG and testosterone combined beyond CRP and HbA1c. The RRNDE was 1.26 (95% CI: 1.09-1.47). For women, the RR for waist circumference (≥88 vs. ≤80 cm) was 1.27 (95% CI: 1.07-1.50). The RRsNIE were 1.08 (95% CI: 0.94-1.22) through all biomarkers, 1.08 (95% CI: 0.99-1.17) through CRP, 1.00 (95% CI: 0.98-1.02) through HbA1c beyond CRP and 1.00 (95% CI: 0.92-1.09) through SHBG and testosterone combined beyond CRP and HbA1c. The RRNDE was 1.18 (95% CI: 0.96-1.45). For men and women, pathways influenced by CRP explained a small proportion of the adiposity-CRC association. Testosterone and SHBG also explained a small proportion of this association in men. These results suggest that pathways marked by these obesity-related factors may not explain a large proportion of the adiposity-CRC association.

With the widespread use of sex-steroid hormones in contraceptives and hormone replacement therapy, there is an increasing need for reliable analytical methods. We report the development of a sensitive and robust UPLC-MS/MS method for quantitation of both endogenous and synthetic sex-steroid hormones in human serum.
We developed and validated a UPLC-MS/MS method to quantify progestogens (etonogestrel, levonorgestrel, medroxyprogesterone acetate, norethindrone, progesterone) and estrogens (estradiol and ethinyl estradiol) with good accuracy, high sensitivity, and excellent robustness. We then applied the method to the analysis of sex-steroid hormones in serum from 451 clinical research participants.
Each UPLC-MS/MS analysis was 6.5 min. The lower limits of quantitation (LLOQs) were 25 pg/ml for the progestogens, and 2.5 and 5.0 pg/ml for estradiol and ethinyl estradiol, respectively. When estradiol was analyzed without assessment of progestogens, the LLOQ was reduced to 1 pg/ml. The calibration curves were linear from 25-50,000, 2.5-2000 (1-2000 for estrogens-only analysis) and 5-2000 pg/ml, respectively. Both the accuracy and precision were below±15% not only for routine validation (intraday and interday), but for long-term (>2 years) assay robustness with external controls, thereby, demonstrating the utility of this method for multi-year clinical trial assessments of progestogens and estrogens. We applied the method to quantify sex-steroid levels in 1804 clinical samples.
We successfully developed a UPLC-MS/MS method, and overcame the matrix suppression to allow sensitive quantitation of both synthetic and endogenous sex-steroid hormones in human serum.
We developed a sensitive and robust UPLC-MS/MS method to accurately measure the levels of sex-steroid hormones in serum. The method overcame matrix interference barriers and achieved excellent long-term stability and reproducibility (≥96.9% accuracy; ≤13.0% relative variability measured with external controls over 2 years), demonstrating its utility in clinical sample analysis.

Obesity is associated with metabolic alterations that may pose a biological link between body fatness and risk of cancer. Elucidating the role of obesity-related biomarkers in cancer development is essential for developing targeted strategies aiming at obesity-associated cancer prevention. Molecular epidemiological studies of the past decades have provided evidence that major hormonal pathways linking obesity and cancer risk include the insulin and insulin-like growth factor-1 (IGF-1) axis, sex-steroid hormones, adipokines and chronic low-grade inflammation. These pathways are interrelated with each other, and their importance varies by obesity-related cancer type. The insulin/IGF-1 axis has been implicated to play an important mediating role in the association between obesity and risk of pancreatic, colorectal and prostate cancer. Endogenous sex-steroid hormone concentrations, in particular obesity-associated pre-diagnostic elevations of estrogens and androgens, play an important role in postmenopausal breast cancer and endometrial cancer development. The adipokines adiponectin and leptin and adipocyte-mediated chronic low-grade inflammation represented by the acute-phase C-reactive protein may explain a substantial part of the association between obesity and risk of colorectal cancer. There is less evidence on whether these hormonal pathways play a mediating role in other obesity-associated types of cancer. In this chapter, the molecular epidemiologic evidence from prospective studies relating circulating obesity-related biomarkers to cancer risk is summarized, taking into account available evidence from Mendelian Randomization investigations aiming at improving causal inference.