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Menopausal oestrogens and breast cancer risk: an expanded case-control study
British Journal of Cancer
|November 1, 1986
Summary
Long-term estrogen use, especially over 20 years, significantly increases breast cancer risk in post-menopausal women. This risk is elevated even further for those with a history of benign breast disease.
Area of Science:
- Endocrinology
- Oncology
- Epidemiology
Background:
- Estrogen therapy is widely used for menopausal symptoms.
- The relationship between estrogen use and breast cancer risk requires further investigation.
Purpose of the Study:
- To evaluate the association between estrogen use and breast cancer risk in post-menopausal women.
- To identify specific patterns of use or patient subgroups with elevated risk.
Main Methods:
- A case-control study involving 1960 post-menopausal breast cancer cases and 2258 controls.
- Data collected through a nation-wide screening program.
- Analysis of risk based on duration of estrogen use and menopausal status.
Main Results:
- Ever using estrogen was not associated with increased breast cancer risk (RR = 1.0).
- A significant trend showed a 50% excess risk for users of 20 or more years.
- Long-term use posed higher risks across all menopausal subgroups and particularly for those with prior benign breast disease (RR = 3.0).
Conclusions:
- Estrogen plays a role in breast cancer etiology, particularly with extended use.
- Risk elevation is most pronounced after prolonged exposure (≥20 years).
- Adverse effects are amplified in women with a history of benign breast disease.