A report from the American Cancer Society finds the breast cancer death rate in the United States continues to drop more than two percent per year, a trend that began in 1990 and is credited to progress in early detection and treatment.
But the report says African American women and women of other racial and ethnic groups have benefited less than white women from the advances that have led to those gains, and that a recent drop in cancer incidence (the rate at which news cancers are diagnosed) is due in part to fewer women getting mammograms.
The findings are published in Breast Cancer Facts & Figures 2007-2008. The report, published every two years since 1996, provides detailed analyses of breast cancer trends and presents information on known risk factors for the disease, factors that influence survival, the latest data on prevention, early detection, treatment, and ongoing and future research.
"While many women live in fear of breast cancer, this report shows a woman today has a lower chance of dying from breast cancer than she's had in decades," said Harmon J. Eyre, M.D., chief medical officer of the American Cancer Society. "Unfortunately, not all women are benefiting at the same level. Perhaps most troubling 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 percent higher in African American women."
Other highlights of Breast Cancer Facts & Figures 2007-2008 include:
- In 2007, 178,480 new cases of invasive breast cancer are expected among women. Excluding cancers of the skin, breast cancer is the most frequently diagnosed cancer among women, accounting for more than one in four cancers diagnosed in U.S women.
- In 2004 (the latest year for which figures are available), approximately 2.4 million women living in the U.S. had a history of breast cancer.
- Between 1990 and 2004, the breast cancer mortality rate decreased by 2.2 percent per year. The decline was larger among younger age groups.
- From 1995-2004, female breast cancer death rates declined by 2.4 percent per year in whites and Hispanics/Latinas, 1.6 percent per year in African Americans, and remained unchanged among Asian Americans/Pacific Islanders and American Indians/Alaska Natives.
- In 2007, approximately 40,460 women are expected to die from breast cancer. Only lung cancer accounts for more cancer deaths in women.
- During 2001-2004, breast cancer incidence rates among white women declined at an average rate of 3.7 percent per year, likely due to lower rates of mammography screening as well as decreased use of hormone replacement therapy (HRT).
- Incidence rates have remained relatively stable for African American women. The lack of a decline may be due to the lack of a significant decrease in mammography screening rates and/or lower rates of HRT use among African American women.
- Among women aged 50 and older, incidence rates have been declining sharply (by 4.8 percent 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 percent per year. In contrast, the incidence rate of larger tumors (>5.0 cm) has increased by 1.7 percent per year since 1992, perhaps due to postmenopausal obesity, HRT use, or both. (Larger tumor size at diagnosis is associated with decreased survival.)
The report details the major modifiable factors associated with breast cancer. Obesity increases risk of postmenopausal (but not premenopausal) breast cancer, as does weight gain during adulthood. Alcohol consumption is consistently associated with increased breast cancer risk, with studies showing two drinks a day may increase breast cancer risk by 21 percent.
Most studies have found no link between active cigarette smoking and breast cancer; the link between secondhand smoke and breast cancer remains controversial. Meanwhile, growing evidence supports a small protective effect of physical activity on breast cancer, with most studies finding reduced risk in women who exercise vigorously for 45 to 60 minutes on 5 or more days per week. However, one study suggests that any level of regular physical activity may reduce breast cancer risk in postmenopausal women.
The report also notes current breast cancer research, including:
- the Sister Study, which is currently enrolling 50,000 cancer-free women who have a sister with a history of breast cancer, will follow participants for at least 10 years in order to analyze information about genes, lifestyles, and environmental factors that may be related to breast cancer risk;
- several approaches to chemoprevention of breast cancer;
- studies indicating that women under age 50 and women with dense breasts may benefit from having a digital rather than a film mammogram;
- research indicating that increased breast density over time may be a more accurate predictor of future breast cancer than a single measurement;
- the use of MRI in detecting cancer in the contralateral (opposite) breast of newly diagnosed breast cancer patients, which could help women make treatment decisions and might spare them from extra rounds of surgery and chemotherapy later;
- improved understanding of breast tumor cell biology and molecular genetics that is enabling researchers to design "rational therapeutics" that are tailored to the unique characteristics of each patient and tumor.
"Taken together, this report highlights the remarkable gains we've made in the fight against breast cancer," said John R. Seffrin, Ph.D., chief executive officer of the American Cancer Society. "But it also puts into focus the challenge before us: to close the gap so all Americans can reap the benefits equally, and to ensure that no American woman faces an increased risk of dying from breast cancer because of her race or ethnicity or because of lack of access to quality care."
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