Breast cancer in postmenopausal women with and without hormone replacement therapy: preliminary results of the MISSION study.
OBJECTIVE
To determine breast cancer prevalence in postmenopausal women with or without hormone replacement therapy (HRT).


METHODS
This was a historical-prospective study with random patient selection. Patients were recruited between January 2004 and February 2005, and allocated to two groups: the 'treated group' comprising postmenopausal women on HRT regimens commonly prescribed in France or who had stopped <5 years previously; or the 'untreated group' of postmenopausal women who had never received HRT or stopped >5 years previously.


RESULTS
In total 6755 patients fulfilled all inclusion criteria: 3383 in the treated group and 3372 in the untreated group. The treated group was younger and less overweight than the untreated group (p < 0.0001). The treated group had fewer late menopauses (p = 0.0002) and fewer first-degree family histories of breast cancer (p < 0.0001). Mean HRT duration was 7.9 years; 30.5% of women were treated for >or=10 years. Breast cancer prevalence was 1.01% for the treated group and 6.21% for the untreated group. The European standardized incidence rate of breast cancer in the untreated group was significantly higher than in the French reference population (comparative incidence figure ratio (CIFR) = 2.24; 95% confidence interval (CI) = 1.50-3.36). In contrast, the European standardized incidence rate in the treated group on the studied HRT regimens (excluding some progestins) was not significantly different from that of the reference population (CIFR = 1.04; 95% CI = 0.35-3.15).


CONCLUSIONS
The differences between the two groups may be due to French gynecologists' treatment strategy of avoiding prescribing HRT to high-risk women, and also perhaps to a specific 'studied HRT' effect.
Espié
Marc
M
Hôpital Saint-Louis, Paris, France.
Mares
Pierre
P
de Reilhac
Pia
P
Chevallier
Thierry
T
Daurès
Jean-Pierre
JP
D000368:Aged; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000473:pathology; D002277:Carcinoma / Q000453:epidemiology* / Q000473:pathology; D015331:Cohort Studies; D004359:Drug Therapy, Combination; D016021:Epidemiologic Studies; D004958:Estradiol / Q000627:therapeutic use; D015914:Estrogen Replacement Therapy / Q000706:statistics & numerical data*; D005260:Female; D005602:France / Q000453:epidemiology; D006801:Humans; D008875:Middle Aged; D009367:Neoplasm Staging; D017698:Postmenopause / Q000187:drug effects*
D004958:Estradiol