Yet even as the screenings produce false positives, they fail to catch forms of breast cancer that develop rapidly, explaining why the more widespread use of screenings has done so little to curb the rate at which late-stage breast cancer is found.
“The sad fact is that there’s a subset of women who develop such an aggressive form of cancer it literally can’t be caught early,” said Welch.
Debra L. Monticciolo, a physician who chairs the American College of Radiology’s Quality and Safety Commission, questioned many of the study’s methods, including the data used to account for fluctuations in the underlying incidence of breast cancer due to factors like the use of hormones.
“It stuns me that this got through peer review,” said Monticciolo.
She added that as a physician, she found it hard to believe that such a large share of screenings produce false positives. If that were the case, there would be countless tales of miraculous recoveries by women who refuse traditional treatment after being diagnosed with early-stage breast cancer.
“I’ve never seen such a case. And there’s nothing like that in the literature,” said Monticciolo.
Most important, she said, new studies continue to confirm the benefits of screenings.
“Mammograms clearly save lives,” she said.
Archie Bleyer, a professor at the Knight Cancer Institute at Oregon Health & Science University who is the study’s other coauthor, said he wouldn’t dream of suggesting that women cease getting mammograms altogether.
“There are clearly women who are benefiting from doing this,” he said.
But he and Welch said their findings suggest that the message to women about mammograms needs to be more nuanced.
“We need to start telling the truth,” said Welch. “We’ve promoted this as if it’s the most important thing a woman can do for her health. . . . And the truth is that it’s a really close call.”
Women in their 40s who feel comfortable getting annual mammograms should not be dissuaded from doing so, he said. “But women who have never felt good about it, who felt coerced into the procedure, should feel equally good about not having it.”
Similarly, Welch said, women who do get screening mammograms and are found to have a tumor in a very early stage may want to consider alternatives to aggressive treatment — engaging in watchful waiting, for instance, or signing up for a clinical trial of drugs that may halt or slow the progression of cancer. Men have faced similar issues in deciding what to do about screening and treatment of prostate cancer, he said.
“We should tell women about the trade-offs and we should allow them to make their own decision,” he said.