Large Portion of Late-Stage Breast Cancers Associated With Absence of Screening
Increasing mammography screening rates and investing in research to improve breast cancer detection technologies should be top priorities, according to authors of a study published in the October 20, 2004, Journal of the National Cancer Institute*. As many as 92 percent of late-stage breast cancer cases in the United States could be diagnosed and treated earlier, when there is greater likelihood of effective treatment, if the healthcare system focused on recruiting women who have not been recently screened, and if early detection techniques could be improved to more accurately detect cancer. The study was conducted by researchers at the National Cancer Institute, part of the National Institutes of Health, and the Cancer Research Network (CRN), a consortium of integrated health plans.
Study results indicated that not having had a screening mammogram for one to three years prior to diagnosis was associated with 52 percent of late-stage breast cancer cases. The authors state that to improve breast cancer outcomes, priority should be placed on reaching unscreened women and encouraging them to have mammograms - especially older, unmarried, less educated, and/or low income women, whom they found were less likely to have been screened. "The good news is that there is a lot known about how to reach women who have never been screened or who fail to get regular mammograms," said Stephen Taplin, M.D., M.P.H., a senior scientist in NCI's Division of Cancer Control and Population Sciences and lead author of the study. "The challenge is to put this knowledge into practice."
The study was based on a review of all medical care received by 2,694 women during the three years prior to their breast cancer diagnosis. Researchers reviewed medical charts and records of women in seven integrated healthcare plans across the United States. The plans offer specialty and primary care within the same system, and serve 1.5 million women over age 50. All offer breast cancer screening mammograms at no or low cost. When the study began in 1999, 71 percent to 81 percent of these women had had mammograms. "Few women in a regularly screened population should be diagnosed with late-stage breast cancer because, in theory, screening should identify cancers before they progress to the late stage," explained Taplin. "However, there were still cases of late-stage breast cancer in this population."
Taplin previously worked at Group Health Cooperative in Seattle, Wash., where he led a team of investigators who were part of the NCI-funded CRN. Taplin and colleagues at participating health plans divided the patients in the study into two groups based on the stage at which their cancer was diagnosed. Women whose cancer had spread throughout the body or who had tumors three centimeters or larger made up one group, while women who were diagnosed in the early stages of breast cancer, when their tumors were smaller, made up the second group. The two groups, which each contained 1,347 women, were matched for age and type of health plan.
A key finding was that women who had not been screened one to three years prior to diagnosis were more than twice as likely to have late-stage breast cancer. This finding illustrates an important reason for receiving regular mammograms: to increase the chance of catching breast cancer early. However, a second finding showed that better screening tests need to be developed. Almost 40 percent of women with late-stage breast cancer had a negative mammogram one to three years before their diagnosis.
"These findings show that improvements in both the implementation of mammography and in the methods we use for early detection could reduce late-stage disease," said Taplin. The researchers also found that women were less likely to have been screened if they were Hispanic, unmarried, or had no family history of breast cancer.
NCI Director Andrew von Eschenbach, M.D., said, "This study helps us identify research priorities for breast cancer screening. To eliminate the suffering and death due to cancer, we need to improve delivery to reach women who don't receive regular mammograms, improve the interpretation of mammography, and find new screening tests. All these things are important to achieve national goals."
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*Taplin SH, Ichikawa L, Yood MU, Manos MM, Geiger AM, Weinmann S, et al. Reason for Late-Stage Breast Cancer: Absence of Screening or Detection, or Breakdown in Follow-up? J Natl Cancer Inst 2004 ;96:1518-27.