More controversy has emerged surrounding mammograms ever since a new report in JAMA recommended that the test be performed based on a woman's risk and preferences.
Dr. Lydia Pace and Dr. Nancy Keating both of Brigham and Women's Hospital in Boston, conducted a systematic review of data spanning 50 years. They examined about 450 studies from 1960 through the present to look for evidence on the benefits and harms of the diagnostic test.
According to their report, annual mammograms lower mortality from breast cancer by about 19 percent, though the benefits vary based on a woman's risk and age. Approximately 1,904 women in their 40s would have to undergo a mammogram to prevent one death, while the same would be true for 377 women in their 60s. The disease is more common as a woman ages. At 40, the risk for breast cancer in the next 10 years is 1.5 percent, but that rises to 2.3 percent by age 50, and 3.5 percent by age 60.
The U.S. Preventive Services Task Force (USPSTF) changed its recommendations in 2009 to recommend women have mammograms starting at the age of 50 every two years, instead of having one every year or two beginning at age 40.
The authors of the report say the benefits of the test are overestimated, while the harms are underestimated. The harms include overdiagnosis and false-positives.
Overdiagnosis refers to detecting cancers that would otherwise not have become clinically evident during a woman's lifetime. In that case, the tumor never grew or the woman died from another cause. The report says about 19 percent of women are overdiagnosed.
False positives are found in about half or more of women who have a mammogram each year for a decade. About 20 percent of these women will need a biopsy. Anywhere from 7 percent to 9.8 percent of women who have mammograms for a decade undergo unnecessary biopsies.
Weighing benefits and harms of mammography "While we need more research on mammography's benefits and harms today, existing data suggest that we have been overestimating the benefits of mammography and underestimating the harms over the years," said Pace.
Keating said it is vital to look at a patient's profile, because some women don't have a longer life expectancy.
"I have 80-year-olds in my practice with life expectancies of 15 or 20 years, and 60-year-olds who will likely only live another year or two," she said. "Those two kinds of patients need different recommendations about whether to continue screenings, and it can't be based simply on the patient's age."
