Risk factors for BC death same for blacks, whites
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African-American women are known to be more likely to die from breast cancer than white women, yet new study findings show that the factors associated with an increased risk of death from the condition are similar in both groups.
“This study found that major known risk factors do not vary considerably between these two groups, so this study underscores the need for all women to follow breast cancer screening guidelines,” said study author Dr. Marjorie L. McCullough, of the Atlanta-based American Cancer Society.
Breast cancer is the most commonly diagnosed cancer in African-American and white women in the United States. But while African-American women are less likely to develop breast cancer than white women, they are about 30 percent more likely to die from the disease.
The reasons for these disparities are unknown, although researchers have speculated that it may be partly due to African Americans’ lack of access to quality health care. Studies have also revealed that African-American women begin menstruating at younger ages, have higher levels of obesity and are less active than white women, factors that may influence their risk of the disease.
Also, African-American women are known to have their cancer diagnosed at later stages and to have more aggressive tumors than white women, factors that other researchers have found to be associated with a lower socioeconomic status.
Risk factors for breast cancer are assumed to be similar for both white and African-American women, but most research has been conducted only in whites.
McCullough and her colleagues therefore examined the anthropometric, reproductive and lifestyle factors associated with the risk of death from breast cancer among postmenopausal African-American women. They analyzed data collected from 21,143 African-American and 409,093 white women who were involved in the American Cancer Society’s Cancer Prevention Study II, which began in 1982.
During a 20-year follow-up period, 257 African-American and 4,265 white women died from breast cancer. Higher body mass index, taller height and physical inactivity increased the risk of death from the disease for both African-Americans and whites, McCullough and her colleagues report in the American Journal of Epidemiology.
For every 5-year age group examined, however, the rate of death from breast cancer was higher in African-American women than in white women.
African-American women with a college education were also about 60 percent more likely to die from breast cancer than those without a high school diploma, the report indicates. This association was not observed among white women.
“There’s no reason to think that college education in and of itself would increase risk only in (African-American) women,” McCullough noted. “It is probably a marker of differences in reproductive patterns in these women that is somehow not being picked up in the same way among white women,” she speculated.
Most of the other factors associated with an increased risk of breast cancer, including reproductive factors like non-childbearing, were similarly associated with an increased risk of death in both groups, McCullough and her team note.
In other findings, breast cancer death rates decreased over time among the African-American women and the rates approached those observed among their white counterparts by the end of the follow-up period. The reason for this is unknown, according to the report, but it is “promising,” as it suggests that the disparity in breast cancer death rates between the two groups may be diminishing.
McCullough told Reuters Health that “there are few known modifiable risk factors for breast cancer, so it is critical to do what is in our control: exercise, maintain a healthy weight and closely follow breast cancer screening guidelines.”
The American Cancer Society recommends annual mammograms for women ages 40 or older and clinical breast self-exams - i.e. exams conducted by a doctor, nurse or other healthcare expert—every three years, during routine healthcare visits, for women in their 20s and 30s.
SOURCE: American Journal of Epidemiology, October 15, 2005.
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