ACS Brawley: Better breast cancer screening tools needed
Brawley noted that age-adjusted breast cancer mortality has decreased by 32.3 percent from 1990 to 2008, with an average rate of decrease of 3.2 percent per year among women ages 40 to 49 and 2 percent per year among women ages 50 and older.
A combination of screening mammography, early detection due to increased awareness and improved treatment is responsible for the decrease in breast cancer mortality, with the contribution of mammography accounting for 15 to 40 percent of the drop, he wrote.
However, Brawley noted, “Although mammography is clearly a life-saving technology that should be used, many overestimate its role in the decrease in breast cancer rates.” He also referred to the high ratio of harms to benefits among women ages 40 to 49.
The list of harms includes false-positive results, false-positive biopsy results, false-negative results and false reassurance, pain related to the procedure, overdiagnosis and overtreatment. About half of women in the U.S. who undergo annual screening beginning at age 40 will have at least one false-positive and more than 5 percent will undergo a biopsy.
Mammography becomes more efficient, according to Brawley, when applied among women with a higher prevalence of disease. Thus, identifying women ages 40 to 49 at higher risk may maximize the benefits and reduce the harms of screening mammography while also more effectively allocating resources, he wrote.
Nevertheless, risk-based screening may present some challenges. “Mammography in women with extremely dense breasts creates several conundrums,” Brawley wrote. These exams are difficult to interpret and there is variability among radiologists in the assessment of density. Plus, employing breast density as a risk factor may require all women to obtain a baseline mammogram at age 40.
Brawley referred to the slight difference in benefits between film and digital mammography and the higher rate of false-positive results with digital among younger women. “This is also evidence that better tests beyond our current technologies are desperately needed.”
Finally, he acknowledged the practical difficulties of risk-based screening. Implementation of individualized guidelines “will be challenging because many healthcare providers and members of the lay community do not understand screening and the concept of risk.”
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