HEALTH NEWS

Study Title:

HRT and Cancer

Study Abstract

Background

Unprecedented declines in invasive breast cancer rates occurred in the United States between 2001 and 2004, particularly for estrogen receptor-positive tumors among non-
Hispanic white women over 50 years. To understand the broader public health import of these reductions among previously unstudied populations, we utilized the largest
available US cancer registry resource to describe age-adjusted invasive and in situbreast cancer incidence trends for non-Hispanic white women aged 50 to 74 years
overall and by county-level rural/urban and poverty status.

Methods

We obtained invasive and in situ breast cancer incidence data for the years 1997 to 2004 from 29 population-based cancer registries participating in the North American
Association of Central Cancer Registries resource. Annual age-adjusted rates were examined overall and by rural/urban and poverty of patients’ counties of residence at
diagnosis. Joinpoint regression was used to assess trends by annual quarter of diagnosis.

Results

Between 2001 and 2004, overall invasive breast cancer incidence fell 13.2%, with greater reductions among women living in urban (-13.8%) versus rural (-7.5%) and low-
(-13.0%) or middle- (-13.8%) versus high- (-9.6%) poverty counties. Most incidence rates peaked around 1999 then declined after second quarter 2002, although in rural
counties, rates decreased monotonically after 1999. Similar but more attenuated patterns were seen for in situ cancers.

Conclusion

Breast cancer rates fell more substantially in urban and low-poverty, affluent counties than in rural or high-poverty counties. These patterns likely reflect a major influence of
reductions in hormone therapy use after July 2002 but cannot exclude possible effects due to screening patterns, particularly among rural populations where hormone therapy
use was probably less prevalent.

From press release:

The recent decline in invasive breast cancer in the US was significantly less pronounced in the poor and those who live in rural areas. Researchers suggest this may be due to varying reductions in the numbers of women taking hormone therapy (HT).

Christina Clarke, Ph.D., led a team of researchers from the Northern California Cancer Center who studied breast cancer incidence data from the largest cancer database available in the US for the years 1997-2004, comparing poor areas against rich and urban areas against rural.

She said, "Between 2001 and 2004, incidence rates of invasive breast cancer declined more than 8% in the United States. "One possible explanation for this is widespread discontinuation of and/or failure to initiate HT. Because this cessation of HT use was more pronounced in rich/urban areas, we wanted to see if there was a corresponding difference in breast cancer incidence between these areas and poor/rural parts of the country".

The researchers found that overall invasive breast cancer incidence fell 13.2%, with greater reductions among women living in urban (-13.8%) versus rural (-7.5%) and low- (-13.0%) or middle- (-13.8%) versus high- (-9.6%) poverty counties. Breast cancer incidence trends for rural counties, which peaked in 1999 and then declined steadily, differed from those observed in urban counties, where rates fell dramatically after 2002. The researchers speculate that this may be due to variations in exposure to the news that HT was associated with breast cancer, they cite a 2007 report that found that the number of newspaper articles about the harmful effects of HT found in the 2002 Women's Health Initiative (WHI) trial correlated with urban residence and likelihood of HT cessation/non-initiation; women in urban areas were potentially exposed to more newspaper articles and had a larger decline in the prevalence of HT use.

Dr. Clarke added that "Understanding what specific populations were involved in the breast cancer declines helps us to better plan prevention efforts for the future, especially with the aging of the baby boomer population into prime breast cancer age."

Study Information

1.Amelia K Hausauer, Theresa HM Keegan, Ellen T Chang, Sally L Glaser, Holly Howe and Christina A Clarke.
Recent trends in breast cancer incidence in US white women by urban/rural and poverty status.
BMC Medicine
2009 June
Northern California Cancer Center, Fremont, CA, USA.

Full Study

http://www.biomedcentral.com/content/pdf/1741-7015-7-31.pdf