Data Misleading for HRT, Breast Cancer Link

Blogger's Note/Opinion: having attended numerous medical conferences/scientific analyzes at the time of, and subsequent to, the WHI publication, the flaws were apparent (and acknowledged) then as they are now;  media hype and poor communications led to a form of 'mass' hysteria amongst women including unneeded suffering; the debates and research will continue

Medpage

Action Points

• The evidence as to whether hormone replacement therapy (HRT) plays a causal role in breast cancer is insufficient to support that hypothesis, and there are major flaws in studies analyzing the data, these researchers contend.
• Point out that aspects of the two ecological studies that violated the principles of causality were time order, detection bias, and lack of adjustment for potential confounders.

"The evidence as to whether hormone replacement therapy (HRT) plays a causal role in breast cancer is insufficient to support that hypothesis, and there are major flaws in studies analyzing the data, researchers stated.
In the years immediately following the publication of the Women's Health Initiative (WHI) in 2002, the use of HRT plummeted, but rates of breast cancer have not consistently followed that pattern, explained Samuel Shapiro, MB, of the University of Cape Town in South Africa, and colleagues.
Moreover, two initial studies assessing the effect on breast cancer incidence following that decline -- often cited as providing strong evidence for an association -- do not hold up under scrutiny, Shapiro's group argued online in the Journal of Family Planning and Reproductive Health Care.
Those studies, one based on data from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) registries and the other drawn from Kaiser Permanente's Northern California health system database, are limited by their ecological design, which simply examines trends in the population without individual-level data, according Shapiro and colleagues.
Ecological studies can suggest a temporal association between an exposure and a disease, such as cigarette smoking and lung cancer during the 20th century, but do not necessarily prove causation, the researchers explained.............

" Moreover, if HRT was the cause of the decline in breast cancer incidence after 2002, declines should have continued in the ensuing years, the researchers argued. But between 2003 and 2007 rates increased in young women and changed little in other age groups.....