Reproductive factors and risk of glioma in women.

National Institute for Occupational Safety and Health, 4676 Columbia Parkway, Cincinnati, OH 45226, USA.
Cancer Epidemiology Biomarkers & Prevention (Impact Factor: 4.32). 10/2004; 13(10):1583-8.
Source: PubMed

ABSTRACT Glioma is the most common primary malignant brain tumor in adults, responsible for 75% of adult primary malignant brain tumors, yet aside from its association with ionizing radiation, its etiology is poorly understood. Sex differences in brain tumor incidence suggest that hormonal factors may play a role in the etiology of these tumors, but few studies have examined this association in detail. The objective of this study was to explore the role of reproductive factors in the etiology of glioma in women.
As part of a population-based case-control study, histologically confirmed primary glioma cases (n = 341 women) diagnosed between January 1, 1995 and January 31, 1997 were identified through clinics and hospitals in four Midwest U.S. states. Controls (n = 527 women) were randomly selected from lists of licensed drivers and Health Care Finance Administration enrollees. In-person interviews with subjects (81%) or their proxies (19%) collected reproductive history and other exposure information.
Glioma risk increased with older age at menarche (P for trend = 0.009) but only among postmenopausal women. Compared with women who never breast-fed, women who breast-fed >18 months over their lifetime were at increased risk of glioma (odds ratio, 1.8; 95% confidence interval, 1.1-2.9). Women who reported using hormones for symptoms of menopause had a decreased risk of glioma compared with women who never used such hormones (odds ratio, 0.7; 95% confidence interval, 0.5-1.1).
These results support the hypothesis that reproductive hormones play a role in the etiology of glioma among women.

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    ABSTRACT: Previous studies on the association between reproductive factors and brain tumor risk in women have provided inconclusive findings. Thus, an updated meta-analysis was performed to obtain more precise risk estimates for brain tumor regarding several common reproductive factors. A comprehensive literature search for relevant publications in the PubMed and Embase databases was carried out from their inception up to June 20, 2014. Pooled relative risks (RRs) with corresponding 95 % confidence intervals (CIs) were calculated. There were 27 independent studies with a total of 12,129 cases and 1,433,915 controls included into the present meta-analysis. We found that an elevated risk of brain tumors (RR = 1.17, 95 % CI 1.06-1.29, P = 0.002), particularly glioma (RR = 1.33, 95 % CI 1.15-1.54, P < 0.001), was related to older age at menarche. Interestingly, stratified analysis by type of brain tumors showed that the longer duration of breast feeding was associated with the risk of meningioma negatively but glioma positively (for meningioma: RR = 0.76, 95 % CI 0.64-0.91, P = 0.002; for glioma: RR = 1.70, 95 % CI 1.14-2.55, P = 0.010). No significant association was observed when estimating the roles of other reproductive factors including parity, age at first birth, menopausal status, and age at menopause in brain tumorigenesis. Our study suggests that older age at menarche is a risk factor of brain tumors and glioma in particular. Additionally, more studies are warranted to further elucidate roles and mechanisms of common reproductive factors in the risk of brain tumors.
    Tumor Biology 08/2014; 35(11). DOI:10.1007/s13277-014-2448-1 · 2.84 Impact Factor
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    ABSTRACT: Purpose The association between female reproductive factors and glioma risk is unclear, but most published studies have been limited by small sample size. We conducted a pooled multisite study of pre- and postmenopausal women, investigating the effect of female reproductive factors, including hormonal medications. Methods Unconditional logistic regression was used to calculate odds ratios (ORs) and 95 % confidence intervals (95 % CIs) assessing the effects of female reproductive factors and female hormonal medications in glioma cases and unrelated controls. Results Menarche over the age of 15 as compared to under 12 was associated with a statistically significant risk for glioma (OR 2.00, 95 % CI 1.47–2.71). Use of oral contraceptive pills (OCP) was inversely associated with risk of glioma (OR 0.61, 95 % CI 0.50–0.74), and there was an inverse trend with longer duration of OCP use (p for trend <0.0001). Use of hormone replacement therapy (HRT) was also inversely associated with risk of glioma (OR 0.55, 95 % CI 0.44–0.68), and there was an inverse trend with longer duration of use (p for trend <0.0001). Compared to those reporting neither OCP use nor HRT use, those who reported using both were less likely to have a diagnosis of glioma (OR 0.34, 95 % CI 0.24–0.48). Conclusions Female reproductive hormones may decrease the risk for glioma. The association appears to be strongest with greater length of use and use of both HRT and OCP.
    Cancer Causes and Control 06/2014; DOI:10.1007/s10552-014-0400-8 · 2.96 Impact Factor


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Jan 23, 2015