Hormonal treatments and epithelial ovarian cancer risk

Estimating the impact of bias in causal epidemiological studies: the case of health outcomes following assisted reproduction

Researchers interested in causal questions must deal with two sources of error: random error (random deviation from the true mean value of a distribution), and bias (systematic deviance from the true mean value due to extraneous factors). For some causal questions, randomization is not feasible, and observational studies are necessary. Bias poses a substantial threat to the validity of observational research and can have important consequences for health policy developed from the findings. The current piece describes bias and its sources, outlines proposed methods to estimate its impacts in an observational study, and demonstrates how these methods may be used to inform debate on the causal relationship between medically assisted reproduction (MAR) and health outcomes, using cancer as an example. In doing so, we aim to enlighten researchers who work with observational data, especially regarding the health effects of MAR and infertility, on the pitfalls of bias, and how to address them. We hope that, in combination with the provided example, we can convince readers that estimating the impact of bias in causal epidemiologic research is not only important but necessary to inform the development of robust health policy and clinical practice recommendations.

Ovarian cancer risk in postmenopausal women using estradiol-progestin therapy - a nationwide study

OBJECTIVE

While previous data link the use of postmenopausal hormone therapy to an increased risk for ovarian cancer, little is known about the impact of various progestins, modes or routes of administration of hormone therapy for this risk. In this nationwide study, we compared relations between different estradiol-progestin (EPT) formulations and epithelial ovarian cancer risk.

METHODS

All Finnish women over 50 years using EPT for at least 6 months (224 015 women with 602 ovarian cancers) during 1994-2006 were identified from the reimbursement register. The incidence of ovarian cancer in EPT users was compared to that in the age-matched background population by means of observed to expected ratio (standardized incidence ratio, SIR).

RESULTS

Ovarian cancer risk was not elevated for EPT use of < 5 years but it was elevated for EPT use of ≥5 years (SIR 1.21, 95% confidence interval (CI) 1.06-1.37). Medroxyprogesterone acetate and norethisterone acetate as components of EPT were associated with similar risks for use for ≥ 5 years (SIR 1.26, 95% CI 0.94-1.64 and SIR 1.42, 95% CI 1.11-1.77, respectively). The risk did not differ between sequential or continuous EPT regimens or between oral or transdermal EPT formulations. The risk elevation for EPT use for ≥ 5 years was seen only for serous (SIR 1.56; 95% CI 1.33-1.80) and mixed cancers (SIR 1.54; 95% CI 1.22-1.91), whereas the risk for mucinous cancer was decreased (SIR 0.47; 95% CI 0.22-0.86).

CONCLUSION

The elevated risk of non-mucinous ovarian cancer in users of EPT ≥ 5 years does not depend on progestin type, mode or route of administration of EPT.

Determining estrogens using surface-assisted laser desorption/ionization mass spectrometry with silver nanoparticles as the matrix

We describe the application of silver nanoparticles (Ag NPs) as matrices for the determination of three estrogens using surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). Because Ag NPs have extremely high absorption coefficients (1.2 x 10(8) M(-1) cm(-1)) at 337 nm, they are effective SALDI matrices when using a nitrogen laser. Three tested estrogens--estrone (E1), estradiol (E2), and estriol (E3)--adsorb weakly onto the surfaces of the Ag NPs, through van der Waals forces. After centrifugation, the concentrated analytes adsorbed on the Ag NPs were subjected directly to SALDI-MS analyses, with the limits of detection for E1, E2, and E3 being 2.23, 0.23, and 2.11 microM, respectively. The shot-to-shot and batch-to-batch variations for the three analytes were less than 9% and 13%, respectively. We validated the practicality of this present approach through the quantitation of E2 in human urine. Using this approach, we determined the concentration of E2 in a sample of a pregnant woman's urine to be 0.16+/-0.05 microM (n=10).

Twin births, sex of children and maternal risk of ovarian cancer: a cohort study in Norway

In a follow-up of 1 208 001 women aged 20–74 years, no significant association was found between twin births (112 cases) and risk, though those with twin girls had a non-significantly higher risk than those with singleton births; among the latter, those with girls only had a higher risk of endometrioid tumours (incidence rate ratio 1.35; 95% confidence interval 1.03–1.76, based on 475 cases) than women with boys only.

Simultaneous determination of natural and synthetic estrogens by EKC using a novel microemulsion

A novel microemulsion based on sodium bis(2-ethylhexyl) sulfosuccinate (AOT) was developed for the simultaneous determination of natural and synthetic estrogens by microemulsion EKC (MEEKC). The microemulsion system consisted of 1.4% w/w AOT, 1.0% w/w octane, 7.0% w/w 1-butanol and 90.6% w/w 20 mM sodium salt of 3-(cyclohexylamino)-2-hydroxy-1-propanesulfonic acid (CAPSO) and 10 mM phosphate buffer at pH 12.5. A baseline resolution in the separation of estrone, 17beta-estradiol, estriol, estradiol 17-hemisuccinate, etinilestradiol, estradiol 3-benzoate, and estradiol 17-valerate was achieved in comparison to the traditional MEEKC system with SDS in less than 15 min. The optimized electrophoretic conditions included the use of an uncoated-silica capillary of 60 cm of total length and 75 microm id, an applied voltage of 25 kV, a temperature of 25 degrees C and 214 UV-detection. Parameters of validation such as specificity, linearity, accuracy, LOD, LOQ and robustness were evaluated according to international guidelines. Due to its simplicity, accuracy, and reliability, the proposed method can be an advantageous alternative to the traditional methodologies for the analysis of natural and synthetic estrogens in different pharmaceutical forms.