Breast Cancer Dip Linked to Locale, Income, HRT Decline

The study reviewed here found that women with higher incomes and women who live in urban areas have had larger drops in breast cancer rates compared to women with lower incomes and women who live in suburban or rural areas. It's not clear what's causing the difference.

Since 2002, there's been a large decrease in breast cancer diagnosis rates. A dramatic change in the use of hormone replacement therapy (HRT) contributed to the decline. Women take HRT to manage bothersome menopausal symptoms, such as hot flashes, night sweats, and insomnia. Research released in 2002 showed that using HRT significantly increases breast cancer risk while HRT is taken and for some time after HRT is stopped. These results led to a large drop in HRT use. Doctors are now much less likely to prescribe HRT to manage menopausal symptoms. Women already using HRT, or who are considering HRT, are now urged to use HRT for the shortest time possible and to consider using estrogen-only HRT. Other research has shown that breast cancer risk linked to HRT use can be minimized by taking HRT for a short period of time and by using estrogen-only HRT (instead of combination HRT, which contains both estrogen and progesterone).

In this study, the researchers looked at the records of more than 475,000 non-Hispanic white women, 50 to 74 years of age, diagnosed with invasive or non-invasive breast cancer between 1997 and 2004. The researchers noted the women's household income and where they lived -- rural, suburban, or urban areas.

The results:

• Breast cancer was more likely to be diagnosed in urban areas compared to suburban and rural areas. More than 85% of breast cancer diagnoses were in urban areas.
• Between 2001 and 2004, the drop in breast cancer rates was largest in urban areas and lowest in suburban and rural areas:
  • Breast cancer rates dropped 13.8% in urban women, 10.7% in suburban women, and 7.5% in rural women.
• Between 2001 and 2004, the drop in breast cancer rates was largest in women with higher incomes and lowest in women with lower incomes.

The study didn't say why these differences happened. One possible reason might be that before 2002 urban women and women with higher incomes were more likely to use HRT. If so, then when HRT use started to decline in 2002 the resulting decrease in breast cancer diagnoses would be greatest in these same groups.

It's very clear, though, that HRT increases breast cancer risk, no matter where a woman lives or how much money she earns. Still, menopausal side effects can dramatically reduce quality of life for some women. These women have to weigh the benefits of HRT against the risks.