Is mammography a flawed technology?

  • Article by: MAURA LERNER , Star Tribune
  • Updated: November 20, 2009 - 9:58 PM

Mammograms are in the spotlight as the uproar continues over how often and at what age women should get them.

In the 1990s, Christine Norton would show up at the annual Twin Cities Women's Expo for three days in a row to hand out instruction cards on breast self-exams. She was such a fervent believer in mammograms that she begged friends to get them every year.

To Norton, who was 43 when she learned she had breast cancer, it seemed like a matter of life and death.

But last week, she was cheering the news that a national panel had questioned the need for women to get routine mammograms in their 40s -- or do monthly self-exams at any age.

While many critics have denounced the new recommendations -- some calling them heartless rationing -- Norton sees them as an honest attempt to cast a spotlight on a flawed technology.

"You need to look at the evidence," says Norton, 63, co-founder of the Minnesota Breast Cancer Coalition. "As more evidence comes in, sometimes you have to change the recommendations."

Unfortunately, she adds, "it's like trying to unring a bell."

Since the U.S. Preventive Services Task Force issued its report last week, many breast cancer survivors have taken it as a personal affront, as though some women's lives aren't worth saving. Defenders say the recommendations are simply an objective assessment of risk versus reward.

But in fact, doubts about mammography have been mounting for decades.

Even now, many on both sides agree that the value of mammograms may have been oversold, while some of the drawbacks -- subjecting many women to unnecessary treatment -- have been minimized or ignored.

At the same time, scientists have been arguing for years over whether it makes sense to screen healthy women in their 40s, when breast cancer is still relatively rare, or to wait till they're 50.

"That 40-49 group has always been a little controversial," said Dr. Douglas Yee, a breast cancer specialist and director of the University of Minnesota's Masonic Cancer Center.

The first big study, begun in 1963, seemed to suggest that mammograms benefited only older women. A New York insurance company studied 62,000 women, ages 40 to 64, for ten years, and found that annual mammograms cut the death rate from breast cancer by 30 percent -- but only in women 50 and older. For the younger group: no change.

That study helped start the first national campaign, in 1973, to encourage American women to get tested.

By 1983, the American Cancer Society started recommending annual mammograms for women 40 and older, as research mounted that it was saving lives.

But doubts persisted. In 1993, a California study concluded that there was little justification for promoting screening for women under 50 unless they were at high risk. That year, the National Cancer Institute came out against routine mammograms at 40. But it reversed itself in 1997 under pressure from Congress and medical and advocacy groups.

Then, eight years ago, Danish researchers published a massive review of mammography studies involving 600,000 women, and concluded: It's "not clear whether screening does more harm than good."

The study, conducted by the prestigious Cochrane Library, acknowledged that routine screening could cut the death rate from breast cancer by 15 to 30 percent. The problem was "overdiagnosis and overtreatment." Out of every 2,000 women, one would be saved because of a cancer found early; but 10 women would get biopsies, surgery or even chemotherapy that they didn't need -- either because of false alarms, or because the mammogram found a type of tumor that was not life-threatening.

Dr. Timothy Wilt of Minneapolis, a member of the task force that issued the guidelines, said the drawbacks of early screening can seem theoretical and abstract.

"We know there's some benefit, but we also know that there's some harm," said Wilt, an internist at the VA Medical Center in Minneapolis. "And we believe it's important for women to have this information."

Wilt admits he was surprised by the intensity of the reaction to the guidelines, which were widely denounced.

Wilt says the report was misunderstood: The task force was not saying that women in their 40s don't deserve mammograms, he said. But as a group, the advantages are less clear, and the risks are higher, when compared to older women.

It said screening shouldn't be recommended before 50, but that women in their 40s should talk to their doctors and decide for themselves.

But many cancer specialists say that's the wrong message.

"I just don't think it's fair to women," said Dr. Tim Emory, U director of breast imaging. "We all know that we can find cancers that are curable in that population. So now it's about false positives and expense."

Dr. Deborah Day, medical director of the Piper Breast Center at Abbott Northwestern Hospital, said she was puzzled by the task force's conclusion. "Even in their statement, the task force said that [mammograms] decreased the mortality rate from breast cancer in the 40-49 age group 15 percent. That seems like a lot to me."

Day admits that there are downsides to routine mammograms. "We do find a lot of cancers, some of them probably aren't lethal cancers," she said. But "until we can figure out which of the cancers don't need to be treated, I think we have to keep doing this."

Christine Norton sees some irony in the uproar. "We used to beg people to get mammograms," she said. Now, "there's an outcry of 'don't take my mammogram away'."

But she adds that conventional wisdom has been wrong before, noting the rise and fall of hormone replacement therapy.

"This is the way science is supposed to be," she said. "They're always questioning. That's what scientists do."

Maura Lerner • 612-673-7384

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