The Journal of Steroid Biochemistry and Molecular Biology
Estrogens in the causation of breast, endometrial and ovarian cancers — evidence and hypotheses from epidemiological findings
Introduction
The exposure to estrogens during different phases of a woman's life can influence the risk of cancer in the main target organs, i.e. the breast, endometrium and ovary. Numerous epidemiological studies report associations between markers of ovarian or placental hormone production and cancer risks. In recent decades, also exogenous hormones — as in oral contraceptives and hormone replacement therapy — have been implicated as risk factors for cancer and also as preventive agents. Epidemiological observations give important clues as to the carcinogenetic role of sex hormones, but need support from clinical and basic research in order to verify and characterize their action in relevant pathways.
This presentation highlights some of the more recent epidemiological findings and their implications for research and for clinical practice.
Section snippets
Breast cancer
Breast cancer is the most frequent cancer among women world-wide, with approxinately a 5-fold higher incidence in some western countries as compared with Asian countries [1]. The cumulative incidence up to 74 years of age is as high as 7–9% in North America and other northern European countries [2]. The incidence has been rising in both developed and developing countries [3], whereas mortality in high-risk countries has been rather stable during past decades [4]. Migration studies reveal
Endometrial cancer
World-wide, endometrial cancer is the sixth most common cancer, accounting for about 2% of all incident cases in women. The incidence varies greatly between countries, being the highest in the USA and Northern Europe [35]. It generally has a favourable clinical course, the 5-year average survival being about 75% [3].
It is established that estrogens cause endometrial cancer. The key mechanism of carcinogenesis is an enhanced and long-standing proliferation of endometrial cells leading to a
Ovarian cancer
Globally, ovarian cancer is the fifth most common cancer among women. Incidence rates are the highest in Scandinavia, with intermediate rates in the USA and with the lowest, but increasing, rates in Japan [51]. Since most of the invasive cancers are diagnosed at an advanced stage, the prognosis is poor, with an average 5-year survival of less than 40% [51]. The non-invasive, borderline subtype, comprising about 20%t of all tumours, is associated with a considerably better prognosis.
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