To screen or not to screen? Experts weigh merits of breast cancer screening vs. overtreatment

Experts debate merits of breast cancer screening

BARCELONA, Spain — Are doctors over-treating breast cancer?

At a breast cancer conference Friday in Barcelona, experts discussed how to implement mammogram screening programs across Europe, balancing fighting cancer with the goal of targeting only those women who need to be screened.

For years, officials have promoted breast cancer screening as the best way to spot the disease and save lives. Yet mammograms are far from perfect and come with an unwelcome side effect: Up to a third of women treated for breast cancer after being identified by the test don’t actually need the biopsies and drugs.

The mammogram issue ignited a fierce debate in the United States last year when an influential panel recommended scaling back screening programs to begin at age 50 instead of 40 — guidelines very close to those already in Europe.

Doubt has also been cast on tests for other cancers like the prostate and colon. Those tests are not commonly recommended because of the high chance of a false positive finding and exposure to radiation.

Some cancers never cause any symptoms and grow too slowly to ever affect patients, but it’s impossible to distinguish between those cancers and more deadly ones. So any identified cancer is treated, which can cause harmful side effects and be psychologically scarring.

“The over-diagnosis problem has been downplayed because people really want to believe screening works,” said Karsten Jorgensen of the Nordic Cochrane Centre in Copenhagen, who has published several papers on the issue. “There is a lot of over-treatment happening, and it is time to re-evaluate whether the benefits really outweigh the harms.”

Yet others say doctors must work with the tests they have.

“Maybe in 20 years we will have a better test to tell us which cancers are the dangerous ones,” said Ingrid Kossler, president of the Swedish Breast Cancer Association, who chaired the session Friday on screening guidelines. “But until then, we have to use what we have and treat the cancers we find.”

Previous studies have shown breast cancer screening programs in countries including Britain, Canada, Denmark and Sweden routinely treat women unnecessarily. In those countries, and in much of Europe, women aged 50 to 70 get a mammogram every two years.

Until last year, U.S. recommendations were for women from age 40 to get a mammogram every year. But new proposals suggested women over 50 get a scan every two years — advice that was rejected by the American Cancer Society and other experts.

Jorgensen said screening has become more of a political issue than a medical one. Officials have spent so many years convincing women to get mammograms that it will be difficult to now change policies, especially with a very vocal and powerful breast cancer lobby.

“It would take a very courageous politician to go up against mammograms,” Jorgensen said.

But reducing the number of women who are being unnecessarily treated also increases the risk that women with breast cancer will be missed.

“We need more targeted screening to identify women who can really benefit from it,” said Jack Cuzick, head of epidemiology at the Wolfson Institute of Preventive Medicine in London. He estimated that for every death prevented, one woman was over-treated.

For breast cancer survivors like Susan Knox, executive director of Europa Donna, a European breast cancer advocacy group, the chance to save women from the disease far outweighs any potential harms.

Knox said women aged 50-70 who are screened for breast cancer have up to a 35 percent lower chance of dying of it than those who aren’t.

“The earlier a breast cancer is caught, the more possibility you have that with good treatment, you won’t die from this disease,” she said.

Others said women should be explicitly told about the potential harms of screening before making a decision.

“Most women who participate overestimate the chances they will benefit,” Jorgensen said. “If we were basing this decision on rationality alone, we would probably come to a different conclusion.”