Women who have a first-degree relative with breast cancer or who have extremely dense breasts may benefit from initiating breast cancer screening at age 40 years, according to a study published today in the Annals of Internal Medicine.
Although there is a general consensus that using mammography to screen women between the ages of 50 and 74 years for breast cancer is worthwhile, heated debates have erupted over whether younger women with certain risk factors may also benefit. To probe which women in their 40s might benefit, a multi-institution team of researchers used 4 different models to compare the risks and benefits of screening women in this age group, both those who have an average risk of breast cancer and those with an elevated risk of developing the disease, with the risk-benefit ratio that has been established for screening older women.
The researchers found that for most women in their 40s, the risks of screening don’t outweigh the benefits. Without any screening, the scientists’ models predict 153 cases of breast cancer diagnoses and 25 breast cancer deaths among 1000 40-year-old women who were followed up for the rest of their lives. But with biennial screening between ages 50 and 74 years, 10610 mammograms would be conducted, about 6 deaths would be averted, and 883 false-positive results would occur. Adding screening for women between 40 and 49 years old who were at average risk of breast cancer resulted in a poorer risk-benefit ratio, according to the analysis, with about 1 life saved and nearly 500 false positives.
However, the models found that women aged 40 to 49 years who had a 2-fold increased risk of breast cancer (such as those with a first-degree relative who had breast cancer or those who have extremely dense breasts) benefited about as much from breast cancer screening as the average woman aged 50 to 74 years.
An editorial by Otis W. Brawley, MD, chief medical officer and executive vice president of the American Cancer Society, that was published simultaneously in the Annals said the findings may help physicians better tailor screening decisions to patients’ individual circumstances.
“Truth be told, [breast cancer screening] cannot avert all or even most breast cancer deaths,” he said. “Mammography, like every screening test, has a potential for harm, and one must carefully weigh the harm-benefit ratio for a specific woman or a specific population of women before advising use of the test.”