The breast cancer death rate in the United States continues to fall by around 2% a year, as it has since 1990, according to Breast Cancer Facts & Figures 2007-2008, a report on breast cancer statistics and trends produced every other year by the American Cancer Society. That's an impressive winning streak for an important indicator of success in the fight against cancer, made possible in large part, the report says, by advances in early detection and treatment.

Those advances have benefited women of some races more than others, data shows. For instance, the cancer death rate for white and Hispanic/Latina women fell by 2.4% between 1995 and 2004, but only by 1.6% for African-American women. And during the same time period, no change was seen in cancer death rates of Asian Americans/Pacific Islanders or American Indians/Alaska Natives.

Also in this issue, authors note a decline in breast cancer incidence -- that is, the rate at which new cancers are diagnosed -- but suggest it may be due in part to fewer women getting mammograms.

On whole, the report shows the continuation of a welcome trend -- a steady decrease each year in the rate of breast cancer deaths. Thanks to better methods of detecting cancers early and treatment advances, American women today are less likely to die of breast cancer than they have been in decades, said Harmon J. Eyre, MD, chief medical officer of the American Cancer Society.

Looking at the issue of race -- and the socioeconomic and genetic factors associated with race -- it becomes clear that this good news is better for some groups of women than for others. "Perhaps most troubling," said Eyre, "is the striking divergence in long-term mortality trends seen between African-American and white females that began in the early 1980s and that by 2004 had led to death rates being 36% higher in African-American women."

Other key statistics included in the report:

• An estimated 178,480 new cases of invasive breast cancer in women will be diagnosed in 2007, and approximately 40,460 deaths will be recorded. Only lung cancer accounts for more cancer deaths in women.
• In 2004 (the latest year for which figures are available), approximately 2.4 million women living in the US had a history of breast cancer. Breast cancer accounts for more than 1 in 4 cancers in US women.
• On average, the breast cancer death rate decreased by 2.2% each year between 1990 and 2004. Younger women saw an even more significant decline during that period.
• Breast cancer incidence among white women -- that is, the rate at which new breast cancers are diagnosed in this group -- fell by 3.7% a year during 2001-2004. Also declining during this time: the use of mammography and hormone replacement therapy (HRT) by white women. There was no significant change in breast cancer incidence among African-American women during this time, coinciding with stable mammography rates and HRT use.
• Among women 50 and older, incidence rates have been on a steep decline (by 4.8% per year) since 2001. Among women under age 50, incidence rates have remained stable since 1986.
• Since 2000, the incidence rate of smaller tumors has declined by 3.8% per year. In contrast, the incidence rate of larger tumors (>5.0 cm) has increased by 1.7% per year since 1992. (Larger tumor size at diagnosis is associated with decreased survival.) Both trends may be tied to an increase in obesity in postmenopausal women, HRT use, or both.

The report details the major risk factors for breast cancer that women have some control over. These include:

• Weight: Obesity increases a woman's risk of postmenopausal (but not premenopausal) breast cancer, as does weight gain during adulthood.
Alcohol use: Women who drink just 2 alcoholic beverages a day face a 21% increase in their risk for breast cancer.

• Secondhand smoke: Although most studies have found no link between cigarette smoking and breast cancer, the link between secondhand smoke and breast cancer remains controversial.
Exercise: Women can lower their risk of breast cancer by exercising vigorously for 45 to 60 minutes on 5 or more days per week. Postmenopausal women can lower their risk, according to one study, with any level of physical activity performed on a regular basis.

The report also takes note of groundbreaking breast cancer research, such as studies looking at the chemoprevention of cancer and at the development and testing of so-called "rational therapeutics," drugs that are tailored to the unique characteristics of each patient and tumor. Also discussed are important investigative trials such as the Sister Study. Investigators are seeking to enroll 50,000 cancer-free women who have a sister with a history of breast cancer. They will follow these women for up to 10 years, collecting information about their genes, lifestyles, and environments and seeking to determine the impact of these factors on breast cancer risk.