The study findings could help women and their healthcare providers better navigate recommendations which can be vague, especially in light of the lack of a recommendation from the U.S. Preventive Services Task Force (USPSTF) on screening older women, noted a team of researchers from the Harvard T.H. Chan School of Public Health, Massachusetts General Hospital, and RTI Health Solutions, all in Boston.
"Real-world data can help inform the care of patients," lead author Dr. Xabier García-De-Albéniz, PhD, of the Harvard T.H. Chan School of Public Health, told AuntMinnie.com. "In our case, the findings help reduce the uncertainty expressed by the USPSTF guidelines that 'the current evidence is insufficient to assess the balance of benefits and harms of screening mammography in women aged 75 years or older.' "
When to stop?
When screening mammography should begin and when it should stop continues to be debated, the researchers noted. Randomized controlled trials have demonstrated that starting mammography screening between the ages of 50 and 69 and continuing it for 10 years decreases breast cancer mortality by 21 deaths per 10,000 women.
But less data exist on when women can safely stop screening for breast cancer. Recommendations from professional groups aren't completely clear, although most do suggest that healthcare practitioners and their patients take life expectancy and quality of life into account when considering whether to stop or continue breast cancer screening.
"Because of the lack of evidence on the effectiveness of screening mammography in older women, current guidelines contain cautious and noncommittal language," the group wrote. "Despite the lack of evidence, many older women continue to have screening mammography -- 52% of U.S. women aged 75 or older had mammography within the past two years, and more than a third of all breast cancer deaths occur in women diagnosed after age 70 years."
Dr. Xabier García-De-Albéniz, PhD, of the Harvard T.H. Chan School of Public Health.
García-De-Albéniz and colleagues sought to estimate the effect of continuing screening on breast cancer mortality among women between 70 and 74 and between 75 to 84. The study included 1.1 million female Medicare beneficiaries in this age group who had had a recent mammography exam, a life expectancy of at least 10 years, and no previous cancer diagnosis. The researchers compared deaths over eight years of follow-up in women who continued annual mammography and those who did not.
The group found that annual mammography would reduce breast cancer mortality over an eight-year period by one death per 1,000 women in those between the ages of 70 and 75, but in those over 75, breast cancer deaths were not substantially decreased over eight years of follow-up.
"With the new information, doctors can inform patients about the expected benefits of either stopping screening after 75 or continuing it," García-De-Albéniz told AuntMinnie.com. "Regardless of the age, women were less likely to receive aggressive therapies (radical mastectomy, chemotherapy) for breast cancer if they continued screening, which [is data that may also] further inform discussions."
In an accompanying editorial, Dr. Otis Brawley from Johns Hopkins University in Baltimore noted that the study's data may be out of date.
"The finding may not fully represent current practice because it uses data gathered between 1999 and 2008 -- the period in which digital mammography was being introduced," Brawley wrote. "Today almost all mammography is digital, and 3D mammography or tomosynthesis is available and is commonly used."
In any case, the benefits of screening mammography in older women remains an important issue to address, according to Brawley.
"One-third of American women who die of breast cancer are diagnosed after age 70 years," he wrote. "It is especially unfortunate that we cannot demonstrate that screening after age 75 years saves many lives. Indeed, the benefit for screening women aged 70 to 74 years is rather small compared with the benefit for women aged 60 to 69 years. This likely reflects more on the current limitations of breast cancer treatment in women over 70 rather than the limitations of mammography because the operating characteristics of mammography improve with age. Hopefully, breast cancer treatment of the geriatric population will improve, and future studies can show that quality screening and treatment lead to a reduction in 'overall mortality' instead of just 'breast cancer-specific mortality.' "
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