More than two-thirds of breast cancer deaths occurred in younger women with no history of mammography or with intervals of 2 years or more between mammograms, a study of 7,300 breast cancer patients showed. Mammographically unscreened women accounted for 71% of breast cancer deaths over an 18-year period. Median age at diagnosis of fatal breast cancer was 49, as compared with 72 for women who died of other causes. The findings support initiation of mammographic screening before age 50, Blake Cady, MD, of Massachusetts General Hospital in Boston, and coauthors reported online inCancer. "Even with effective adjuvant therapies, the best method for women to avoid death from breast cancer is to participate in regular mammography screening," the authors concluded. "Regular screening increases the likelihood of detecting nonpalpable cancers, and annual screening further increases the likelihood relative to biennial screening." "Furthermore, detecting and treating breast cancer in younger women to prevent death may further increase the disease-free life years saved," they added. "Our findings suggest decreasing the intensity of efforts to screen women older than 69 years while concomitantly emphasizing efforts to screening young women in particular." Breast cancer screening by mammography has a controversial history. Studies have shown that early detection of breast cancer reduces the risk of fatal breast cancer. However, the optimal age to initiate screening and the interval between screens have remained unresolved. The controversy gained momentum in 2009 when the United States Preventive Services Task Force (USPSTF) recommended that routine screening mammography begin at 50 and that screening should be optional for younger women. The USPSTF also suggested biennial screening, rather than annual, as an option for average-risk women. The USPSTF position drew criticism from the American Cancer Society, American College of Radiology, and other organizations with a stake in breast cancer diagnosis and management. In general, critics supported annual screening and initiation of screening at a younger age. Most randomized trials of screening mammography have shown that women offered mammography have significantly lower breast cancer mortality than do women who are not offered mammography. Results of those trials have formed the basis of clinical recommendations. However, randomized trials underestimate the effectiveness of screening mammography because of their focus on women who are offered mammography instead of women who are actually screened, the authors stated in their introduction. Consequently, the recommendations do not reflect the survival benefit demonstrated by long-term follow-up of patients who undergo screening. To determine the survival benefit of women who have been screened, Cady and colleagues analyzed data on 7,703 patients who had newly diagnosed breast cancer during 1991 to 1999. Follow-up continued to 2007. The authors also examined duration of screening interval, defining biennial screening as intervals of no more than 2 years. Women whose most recent screen occurred more than 2 years in the past were included in the unscreened group. The data included demographics, use of mammography, surgical and pathology reports, disease recurrence, and death. Investigators designated mammograms as screening or diagnostic on the basis of absence or presence of signs and symptoms of breast cancer. The authors determined that 1,705 of 7,703 women died during follow-up, including 609 breast cancer deaths. Analysis of breast cancer deaths by screening status showed that screen-detected tumors accounted for 118 deaths, most of which (111) involved women whose tumors were detected after two screening mammograms that occurred no more than 2 years apart. Additionally, 60 deaths resulted from "interval cancers," defined as tumors that occurred in women who had at least one negative mammogram performed no more than 2 years previously. Unscreened women accounted for 395 breast cancer deaths. An additional 36 deaths involved "off-program" women, defined as patients who had a history of mammography but who had not been screened in more than 2 years. Overall, interval cancers accounted for 34% of breast cancer deaths in screened women, but investigators found an inverse relationship between age at diagnosis and the proportion of deaths attributable to interval cancers. Among women younger than 40 at diagnosis, 60% of deaths involved interval cancers, declining to 47% among women 40 to 49, 28% in women 50 to 59, 26% in women 60 to 69, and 24% in women 70 or older. Investigators also analyzed breast cancer and nonbreast cancer deaths by age. Half of all breast cancer deaths occurred in women younger than 50 and 69% before age 60. In contrast, 83% of nonbreast cancer deaths occurred in women older than 60. The data speak to the controversy about whether screening mammography should begin at age 50 or earlier. The results are consistent with much of the literature showing that screening mammography lowers the stage at cancer detection, said Clifford Hudis, MD, president of the American Society of Clinical Oncology. Earlier stage, smaller tumors, and lower nodal involvement are all associated with improved outcomes in breast cancer. "Some would argue that cancers are cancers, and whether they are detected early or late, the outcome is the same," Hudis, of Memorial Sloan-Kettering Cancer Center in New York City, told MedPage Today. "This study suggests that is not true, that the stage really matters, even if you have changed the stage at detection." "This provides a little more support for the routine use of mammography, which is important because of the ongoing circular debates about screening," he said. Source reference: Webb ML, et al. "A failure analysis of invasive breast cancer. Most deaths from disease occur in women not regularly screened" Cancer 2013; DOI: 10.1002/cncr.28199.
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