Hormonal therapy estrogen/progestogen combinations

Among women in the estrogen-progestogen arm, there was one serious adverse event for every 100 women treated for 5 years. Specifically, it suggested that for every 10,000 women taking combined hormone therapy, there would be 8 more cases of breast cancer, 7 more cases of myocardial infarctions, 8 more cases of stroke, and 8 more cases of pulmonary embolism. However, 6 fewer colorectal cancers... 

Four combination estrogen and progestogen regimens are currently in use continuous-cyclic (sequential), continuous-combined, continuous long-cycle (or cyclic withdrawal), and intermittent-combined (or continuous-pulsed) hormone therapy. The latter two have been introduced recently. Sequential hormone therapy results in... 

In a reanalysis of 51 studies, less than 5 years of therapy with combined estrogen and progestogen was associated with a 15% increase in risk for breast cancer, and the risk increased with greater duration of treatment. Five years after discontinuation of hormone replacement therapy, the risk of breast cancer was no longer increased. 

Suggestive case histories raised at an early phase the notion of a possible correlation of oral contraceptives with endometrial cancer. Among cases of endometrial cancer there seemed to be an excess of users of oral contraceptives, particularly of the early high-dose estrogen type. With the virtual demise of these early products, the situation seems to have reversed a 1983 study from the Centers for Disease Control (CDC) in Atlanta showed that women who had used fixed combinations for oral contraception at some time in their lives had a relative risk of endometrial cancer of only 0.5 compared with never-users (112). The protective effect occurred only in women who had used oral contraception for at least 12 months, and lasted for at least 10 years after withdrawal. The WHO adopted the same view in 1988 in the light of multinational data (113). As in the case of hormonal replacement therapy, the protective effect seems to be due to the progestogen component. 

Rozenberg S, Caubel P, Lim PC. Constant estrogen, intermittent progestogen vs. continuous combined hormone replacement therapy tolerability and effect on vasomotor symptoms. Int J Gynaecol Obstet 2001 72(3) 235-43. 

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