Decline in hormone replacement prescription and fall in breast cancer incidence: an epidemiological discourse.
BACKGROUND
Between 2002 and 2003 the incidence of invasive breast cancer among women aged 50 to 69 years declined considerably in the US. This decline was accompanied by a substantial fall in prescription rates of estrogen-progestin (EG-HRT).


METHODS
Selective literature search in PubMed from 01/2003 to 12/2007 using the key words "hormone replacement therapy," "incidence," and "breast cancer."


RESULTS
The parallel decline in EG-HRT and breast cancer suggests a causal link. Up to now, alternative explanations for the decline of the incidence can either be refuted or revealed as implausible.


CONCLUSIONS
Detailed incidence trend analyses in the coming years and a close monitoring of EG-HRT prescription rates in and beyond the US. promise important insights. If EG-HRTs are carcinogenic, the extent of this effect remains unclear. If cessation of EG-HRT therapy only delays the appearance of detectable breast cancer, a long-term increase in incidence would be expected in women of age 50 and older, even with low prescription rates. However, if cessation of EG-HRT also stops tumor growth, the anticipated incidence will be permanently lower in the future.
Stang
Andreas
A
Sektion Klinische Epidemiologie, Institut für Medizinische Epidemiologie, Biometrie und Informatik, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, Magdeburger Strasse 8, Halle, Germany. andreas.stang@medizin.uni-halle.de