Hormone Replacement Therapy and Cancer Survival: A Longitudinal Cohort Study

Background

Hormone replacement therapy (HRT) is a significant treatment for menopausal symptoms, including vasomotor symptoms, urogenital atrophy, and postmenopausal osteoporosis. However, its usage has declined due to concerns over increased risks of cardiovascular events and breast cancer. This study seeks to clarify which women can safely use HRT to treat menopausal symptoms without unduly increasing their risk of adverse outcomes.

HRT in Women with Cancer

The relationship between oestrogen and cancer is complex, with evidence suggesting it can both accelerate and inhibit cancer progression depending on the cancer type. The study aims to explore how HRT can be safely provided for women experiencing menopausal symptoms, especially those who have survived or are living with cancer.

Study Design and Data Source

The study is a population-based cohort study using the QResearch linked database, which includes a nationally representative sample of English women. It will analyze HRT prescriptions, considering the specific compound, dose, route of administration, and duration of exposure.

Outcomes

The primary outcome is cancer-specific mortality, with secondary outcomes including incident cases of cancer, all-cause mortality, CVD, and VTE events. The study will also examine confounding variables such as demographic and lifestyle factors, tumor-specific factors, and cancer treatment within six months of diagnosis.

Statistical Analysis

The analysis will involve time-dependent Cox regression models to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for HRT use after cancer diagnosis, adjusting for potential confounders. The study will also conduct sensitivity analyses to check for potential bias and subgroup effects.

Limitations

The study acknowledges limitations, including the completeness of stage data and potential sources of bias from differing prescribing patterns of HRT for women with cancer. It will address these concerns through various sensitivity analyses and the use of multiple imputation for missing data.

Conclusion

This study aims to provide valuable insights into the safety of HRT use in women with cancer, contributing to the understanding of the role of oestrogen in cancer progression and helping women and clinicians make informed decisions regarding HRT use.