由 Brendon Nafziger
, DOTmed News Associate Editor | February 24, 2012
More women in their forties are having their breast cancers picked up by mammograms, and this is linked with less aggressive treatment and a lower risk of relapse and cancer-related death, according to a new prospective cohort study at a Seattle hospital. The trend towards mammography-detected cancers, and away from finding the cancer due to patient complaints or during an unrelated doctor visit, also coincided with finding the disease at an earlier stage, the study said.
Much of the debate around mammography screening centers on whether younger women ought to be screened. For instance, controversial 2009 guidelines from the U.S. Preventive Services Task Force argued women at normal risk for the disease should only get screened starting in their fifties. While the new study, published in the current issue of the journal Radiology, doesn't compare screened versus nonscreened populations, it does suggest that the earlier scans might be doing women some good.
"Our prospective study empowers physicians and patients with data demonstrating the reduction in morbidity associated with (mammography-detected) breast cancer in the 40-49-year age group," write the authors. The corresponding author, Judith Malmgren, is an epidemiologist with the University of Washington and the president of HealthStat Consulting.
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The study, run at Seattle's Swedish Medical Center, tracked 1,977 women with breast cancer, aged 40 to 49, between 1990 and 2008. Over that 18-year period, the proportion of cancers detected by mammography increased from 28 percent to more than half of all cases, the researchers said. Meanwhile, the number of cancers found after a patient showed up complaining of symptoms or otherwise found by the doctor declined, the researchers said.
Patients whose cancers were found with mammography seemed to have somewhat better outcomes. For one, they were more likely to get less aggressive treatments, such as chemotherapy, surgery and radiation therapy (32 percent of mammography-detected patients versus 60 percent of patient or physician-detected ones) or radical mastectomies (25 percent of mammography cases versus 47 percent of the patient and physician-detected ones).
Also, they were less likely to die of the disease (4 percent of mammography-detected cases versus 11 percent of the others) or experience a relapse (6 percent versus 17 percent). At five years, disease-free survival rates were 94 percent for mammography-detected patients and 88 percent for the others, the study said.
Women in the mammography-detected group often had cancers discovered at an earlier stage, with 83 percent of the stage 0 cases found in this group. Most of these early-stage lesions were ductal carcinoma in situ, a non-invasive cancer which "may not always hold a mortal threat of disease if untreated at an early stage," the authors said. However, even when excluding these cases, mammography-detected women had less aggressive treatment and better survival rates in the study, the authors said.