Yet Another Study Confirming That Discontinuation of HRT Led to Drops in Breast Cancer Rates

“Reductions in postmenopausal breast cancer incidence observed in the US were strongest in White women, intermediate in Asian/Pacific Islander and Hispanic women, and absent in African-American women. In all groups, declines were most evident for hormone receptor-positive, lobular, and small cancers. While this and other ecologic analyses cannot definitively speak to the influence of population-wide reductions in mammographic screening or other risk factors, disproportionate declines in the incidence of hormone-sensitive tumor subtypes among racial/ethnic populations that most commonly use HT bolster the hypothesis that mass HT discontinuation after mid-2002 was the predominant cause of recent breast cancer declines.”

A study published in late December of 2007 in Breast Cancer Research confirms what has been suspected for much of the past several months – that the significant drop in the use of combination hormone therapy replacement drugs (such as Prempro and Premarin taken in combination with Provera) after publication of the results from the Women’s Health Initiative Study in July of 2002 have resulted in significant and substantial reductions in the diagnosis of new cases of breast cancer since then. Another study focusing moe on Caucasian women was published in February of 2007 and concluded:

“The apparently stunning impact of EP [the combination use of estrogen and progestin] on the overall breast cancer burden prior to 2002 reflects its status as a common exposure among women at the ages of highest breast cancer incidence. This, coupled with a population-wide relative risk that probably exceeds 1.24 (the only risk estimate provided in the Prempro labeling prior to January of 2007), made EP a previously under recognized contributor to the overall breast cancer burden in the US for the years preceding the WHI. If even a proportion of the 18,000 or more EP-attributable cases of breast cancer that were not diagnosed in the US in 2003 and 2004 are never diaganosed, the impact of HT [hormone replacement therapy drug] cessation for breast cancer prevention will be substantial.”

The study included researchers from the Northern California Cancer Center (http://www.nccc.org/site/c.foJNIXOyEpH/b.2577075/k.BE87/Home.htm) and Stanford University and examined breast cancer data from thirteen different registries that are part of the SEER (Surveillance, Epidemiology, and End Results) cancer registry. The study focused on data from 1992 to 2004 with regard to women who were 50 years of age or older and grouped them according to age, race/ethnicity, and type of breast cancer tumors. The study focused on women who were Asian/Pacific Islander, Hispanic, African-American, and non-Hispanic White women, since earlier studies generally involved primarily women who were white and of European descent. The authors concluded that the reductions that have been noted in diagnosis of new breast cancer cases since the decline in use of combination HRT products varied widely among various racial and ethnic groups, but this variation is explained by the well-established variances in the use of HRT products among these very same groups but did not correspond with known patterns of mammography use in these same groups.