AIM: Several studies indicate that use of hormone replacement therapy (HRT) is 
associated with an increased risk of intracranial meningioma, while associations 
between HRT use and risk of other brain tumors have been less explored. We 
investigated the influence of HRT use on the risk of glioma in a nationwide 
setting.
METHODS: Using population-based registries we conducted a case-control study 
nested in the Danish female population. We identified all women aged 55-84 years 
with a first diagnosis of histologically verified brain glioma during 2000-2009. 
Using risk-set sampling, each case was matched on birth year to eight population 
controls. Ever use of HRT was defined as ≥2 HRT prescriptions and categorized 
according to type (oestrogens only, combined oestrogen-progestagen and 
progestagen only) and duration of use (<1, ≥1 to <5, ≥5 to <10, and ≥10 years). 
We used conditional logistic regression to compute odds ratios (ORs), with 95% 
confidence intervals (CIs), for glioma associated with HRT use, adjusting for 
potential confounders.
RESULTS: We identified 658 cases and 4350 controls. Ever use of HRT was 
associated with an OR of 0.9 (95% CI: 0.8-1.1) for glioma. For long-term use 
(≥10 years) we found ORs of 1.1 (95% CI: 0.7-1.7) for HRT overall, 1.6 (95% CI: 
0.9-2.6) for oestrogen only, 0.8 (0.4-1.6) for combined oestrogen-progestagen, 
and 2.2 (0.9-5.5) for progestagen. Tests for trends were statistically 
non-significant in all strata.
CONCLUSION: Use of HRT overall was not associated with an increased risk of 
glioma. However, our findings indicate that prolonged use of oestrogen only or 
progestagen may be associated with an increased risk of glioma.