The benefits of screening women for breast cancer to save lives outweighs the risks, a new European review suggests.
Mammography is under scrutiny since U.S. researchers questioned its value for detecting breast cancer last year.
In Thursday's issue of the Journal of Medical Screening , European researchers reviewed breast cancer screening programs in 18 countries involving 12 million women between 2001 and 2007 to make what they called a "balance sheet" summary.
They estimated that for every 1,000 women screened every two years from the age of 50 to the age of about 68 to 69, between seven and nine lives would be saved, and four cases would be overdiagnosed.
Overdiagnosis is often defined as a diagnosis of breast cancer through screening that would not have been diagnosed in a woman's lifetime had she not been screened.
"Overall the current European evidence shows that about two lives are saved for every case of overdiagnosis," Marco Zappa and Antonio Federici of the Italian Ministry of Health said in a commentary accompanying the research.
Another potential harm of screening arises from suspicious findings on mammograms that do not result in a breast cancer diagnosis but can lead to more testing, biopsy and surgery.
The researchers estimated that for every 1,000 women screened, 170 women would have at least one recall followed by a non-invasive assessment before absence of cancer could be confirmed. Of these, 30 women would have at least one recall followed by invasive procedures, such as a biopsy, before confirming a negative result.
These "false positives" can cause women stress and anxiety until they receive an all-clear.
A summary of the research noted that breast cancer screening programs can only be fully evaluated after at least 20 years.
An earlier review of the benefits and harms of screening was based on randomized trial results after 10 years of screening, the Euroscreen researchers said.
A second paper appearing in this week's New England Journal of Medicine said that expert recommendations often focus on death, which is easily determined and counted, but ignore other vital aspects of life that aren't so easily quantified.
"For a woman in her 40s, how do you balance the anxiety and discomfort of a biopsy for a false positive mammogram against the possible need for more extensive surgery, radiation or chemotherapy for a larger cancer detected later in life?" Pamela Hartzband and Jerome Groopman wrote in an essay.
"There are real complexities and uncertainties that we all, patients and physicians alike, confront in weighing risk and benefit. Wrestling with these uncertainties requires nuanced and individualized judgment. It is neither ignorant nor irrational to question the wisdom of expert recommendations that are sweeping and generic. There is more to life than death," they concluded.