Report Highlights Trends in Breast Cancer Incidence Among Ethnicities (dateline March 8, 2004)
A new report by researchers from the American Cancer Society highlights the trends in breast cancer incidence among racial ethnicities in the United States. The report also highlights a surprising finding: an increase in large breast tumors among white women. Possible reasons for this increase include the use of hormone replacement therapy and delayed childbirth. Overall, more African-Americans are diagnosed with large breast tumors than white women and African-Americans are significantly more likely to die from the disease.
Over one million women develop breast cancer each year worldwide, and 600,000 die from the disease. Approximately 211,300 new cases of invasive breast cancer are expected to be diagnosed this year in the United States in addition to 55,700 cases of in situ breast cancer, an early form of breast cancer where the disease is still confined to the breast ducts. An estimated 39,800 deaths are expected to occur from breast cancer in the U.S. this year.
According to a report by Asma Ghafoor, MPH and colleagues from the American Cancer Society, the rate of breast cancer cases has increased from 1980 to 2000 but slowed during the 1990s. In particular, rate of breast cancer continues to increase among white women but has stabilized among African-Americans since 1992. From 1992 through 2000, rates of breast cancer increased among Asian Americans/Pacific Islanders and Hispanics but decreased among American Indians/Alaska Natives.
Surprisingly, the researchers found that the incidence rate of large tumors (more than 5 centimeters) increased by 2.1% per year, in white women only. In 1992, there were 5.6 cases per 100,000 white women, and by 2000, there were 6.3 cases per 100,000 of large breast cancer tumors among white women. Overall, more large breast cancer tumors occur in African-American women, but a similar increase in incidence was not seen among this group of women.
Researchers cite several possible reasons for the overall increase in breast cancer in the past two decades. These reasons include older age at birth of a first child, the use of hormone replacement therapy (HRT), and access to and use of screening. White women are more likely to delay having children and use HRT. For example, the First National Health and Nutrition Survey which followed women from 1970 to 1992 found that the proportion of those who used HRT for at least five years after menopause was 23% among whites and 8% among African-Americans.
On the bright side, the researchers reported a decrease in deaths from breast cancer since 1990, by 2.5% per year among white women and 1% per year among African-American women. From 1992 through 2000, breast cancer death rates also decreased in Hispanics by 1.4% per year, and rates remained unchanged among Asian Americans/Pacific Islanders and American Indians/Alaskan Natives.
In the 1980s, deaths from breast cancer were nearly equal among white women and African-American women, but by 2000, African-Americans had a 32% higher rate of death from breast cancer. Reasons for this disparity include access to mammography and high quality breast cancer treatments. For example, African-Americans are less likely than white women to receive radiation therapy after breast-conserving surgery (lumpectomy).
In light of this report, the researchers emphasize the need for research advances into the causes of breast cancer as well as preventive and treatment strategies. In addition, applying current knowledge about breast cancer to the entire population would likely result in significant progress with the disease.