An overview of menopausal oestrogen–progestin hormone therapy and breast cancer risk

Abstract

Results from the Women's Health Initiative (WHI) trial support findings from observational studies that oestrogen -progestin therapy (EPT) use is associated with an increase in breast cancer risk. We conducted a meta-analysis using EPT-specific results from the Collaborative Group on Hormonal Factors in Breast Cancer (CGHFBC) pooled analysis and studies published since that report to obtain an overview of EPT use and breast cancer risk. We also assessed risk by histologic subtype of breast cancer, by schedule of the progestin component of EPT, and by recency of use. We estimate that overall, EPT results in a 7.6% increase in breast cancer risk per year of use. The risk was statistically significantly lower in US studies than in European studies -5.2 vs 7.9%. There was a significantly higher risk for continuous-combined than for sequential EPT use in Scandinavian studies where much higher total doses of progestin were used in continuous-combined than in sequential EPT. We observed no overall difference in risk for lobular vs ductal carcinoma but did observe a slightly higher risk for current vs past EPT use. The Collaborative Group on Hormonal Factors in Breast Cancer (CGHFBC) (1997) pooled data from 51 epidemiologic studies to obtain an overall estimate of breast cancer risk associated with menopausal hormone therapy (HT) use. The risk estimate for oestrogen therapy (ET) use was based on large numbers of cases and controls, but the oestrogen -progestin therapy (EPT) result was not. Since then, a number of statistically powerful studies have evaluated EPT in relation to breast cancer risk. Some of these further evaluated differences in risk by schedule of progestin administration, that is, sequential vs continuous-combined use (Magnusson et al, 1999;Ross et al, 2000;Schairer et al, 2000;Newcomb et al, 2002;Porch et al, 2002;Weiss et al, 2002; Million Women Study, 2003;Olsson et al, 2003;Stahlberg et al, 2004), and in relation to histologic subtype of breast cancer (Schairer et al, 2000;Daling et al, 2002;Newcomb et al, 2002;Newcomer et al, 2003;Ursin et al, 2002;Weiss et al, 2002).We conducted a meta-analysis of the results reported by the CGHFBC and studies published since that overview through March 2004 to provide a more precise estimate of the risk from EPT and how it is affected by schedule of progestin administration and histologic subtype. MATERIALS AND METHODSWe used the Medline database to compile a list of studies subsequent to the CGHFBC report investigating the relationship between EPT and incident breast cancer risk using the Medical Subject Headings (MeSH): postmenopausal, oestrogen progestin therapy (or combined therapy), and breast cancer. For this analysis we did not include studies that presented results only for overall HT, nor did we include studies that only evaluated ET use, nor studies only evaluating breast cancer mortality. A total of 22 studies were identified for possible inclusion (Persson et al, 1996(Persson et al, , 1997Magnusson et al, 1999;Li et al, 2000Li et al, , 2002Li et al, ,...

Oral progestagens before menopause and breast cancer risk

“…Our results are consistent with a promoting effect of progestagens on tumour cells, by showing an increase in risk with Cancer, 1996Cancer, , 1997Lee et al, 2005) suggesting that the increase in risk might be limited to current use of hormonal treatments. Our study had some limitations.…”

Use of exogenous hormones and the risk of breast cancer: results from self-reported survey data with validity assessment

“…With respect to use of hormone replacement therapy (HRT), several studies have indicated that HRT use increases the risk of BC. The risk is even higher with longer duration of use and most specifically with the use of estrogen-progestin combination [19][20][21][22].…”

Are mammotropic hormones mainly permissive for the development of breast cancer?

“…3,4 Moreover, case-control investigations of variable sample size and characteristics have also been performed during the last 3 decades. 5,6 The collective evidence for most of the investigated mammotropic hormones 1 -including estrone, estradiol, androstenedione, dehydroepiandrosterone sulfate (DHEAS) and testosterone-as well as prolactin, 2 insulin-like growth factor 1 (IGF-1) 7 and perhaps, on the basis of evidence regarding hormone replacement treatment, even progesterone, 8 suggests that they are positively associated with breast cancer risk. Only for adiponectin, there is evidence that it may be inversely associated with breast cancer risk.…”