Postmenopausal hormone therapy and breast cancer: what is the problem?

Observational studies provide evidence that breast cancer risk is increased with long-term oral use of postmenopausal estrogen replacement therapy (ET). Various large cohort studies have shown that the addition of a progestogen in combined hormone replacement therapy (EPT) increases this risk further. Prospective, randomized controlled trials have confirmed this for the continuous combined regimen. So, why not tell our patients, "Stop using ET and EPT, it is dangerous to your health!"? The answer is: there are too many problems to allow such an oversimplified, definite statement. What is the problem? There is more than one! The problems are as follows: In conclusion, we have a problem as we cannot formulate any general advice that holds for the majority of European postmenopausal women due to lack of consistency, lack of biological plausibility, and lack of relevance of randomized clinical trial data to our daily practical work. So, we have a problem and not a firm basis for undisputable statements.