Mammography Use and False Positives Among Women Younger Than 40 Years Old Differ Between Minority Populations
December 7, 2009
• Majority of first mammograms under age 40 were for screening purposes.
• Rates of false positives vary more in diagnostic mammograms.
HOUSTON - Breast cancer screening guidelines generally recommend mammography begin at age 40. However, based on prior national research, an estimated 34 percent of non-Hispanic black women, 30 percent of non-Hispanic white women and 22 percent of Hispanic women aged 30 to 39 have reported having a mammogram.
"Our goals are to better understand who these women are that are getting mammograms at such a young age and their outcomes," said Julie M. Kapp, Ph.D., M.P.H., assistant professor at the University of Missouri-Columbia and lead author of the study, who presented the data at the American Association for Cancer Research Frontiers in Cancer Prevention Research Conference, Dec. 6-9 in Houston.
Through the NCI Breast Cancer Surveillance Consortium, the researchers examined the first mammograms of women aged 18 to 39 with no prior history of breast cancer. The sample included 99,615 mammograms.
Even though the risk of developing breast cancer before age 40 is lower than 1 percent, research showed that the majority of first mammograms in this study were for screening purposes, rather than evaluation of a breast problem. Screening mammograms ranged from 69 percent among black women to 81 percent among Asian women.
"Women younger than 40 at low or average risk who receive screening mammography may be exposed to unnecessary negative harms, such as false positive results, additional radiation and invasive procedures," said Kapp.
False positives from screening mammograms varied only slightly between ethnic groups, ranging from 10.4 percent to 14.1 percent. However, false positive rates from diagnostic mammograms showed wider disparity, from 8.7 percent for white women to 18.2 percent for Asian women.
Kapp and colleagues are concerned that the impact of false positives on women of various racial/ethnic groups may vary and deter future mammography screening for some. For instance, previous studies have shown black women have greater odds than white women of having multiple mammograms before the age of 40, but black women older than 40 years are less likely to receive mammography screening.
Future research should address why, and what impact early screenings at a young age could have on future mammography use in women older than 40 years, when the risk of breast cancer is higher, according to Kapp.
This work was supported by a grant from the National Cancer Institute [grant number R03CA134196 to JMK]. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Cancer Institute or the National Institutes of Health. Data collection for this work was supported by a National Cancer Institute-funded Breast Cancer Surveillance Consortium co-operative agreement [grant numbers U01CA63740, U01CA86076, U01CA86082, U01CA63736, U01CA70013, U01CA69976, U01CA63731, U01CA70040]. Breast Cancer Surveillance Consortium: www.breastscreening.cancer.gov
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