Dispatch November 2009

Rethinking the Mammogram Guidelines

Many are dismissing the new breast cancer recommendations as a hasty reversal of years of authoritative medical advice. But evidence weighing against screenings for women in their 40s has in fact been mounting for years.

In January 2002, Umea, Sweden was about the coldest inhabited place on earth. But it was at Umea University, in an office festooned with Sweden's ubiquitous winter candles, that Lennarth Nystrom was carrying out his critical research: analyzing and updating the half-dozen Swedish mammography studies that tell us nearly all of what we know about the value of that procedure.

Sweden is the birthplace of mammography, and the Swedish mammography trials, which have monitored some 265,000 women in Malmo, Stockholm, Goteborg and other Swedish cities for nearly 30 years, are accepted by physicians and researchers worldwide as the most authoritative.

When I visited Nystrom that frigid winter, he and several distinguished Swedish colleagues were preparing to publish a periodic update of five of the six major Swedish trials.

Their conclusion, which the update itself called "surprising": there was "virtually no" benefit from mammograms for women under 55.

That was more than seven years ago.

Much of the confusion and controversy spawned by this week's report, by a government-sponsored task force, that screening mammograms are not helpful and may be harmful for women under age 50, has to do with the apparent suddenness of the decision, reversing a quarter-century of advice to begin annual screening at age 40.

But while the report is new, the underlying data has been available since March of 2002, when The Lancet, a widely respected British medical journal, published the Swedish update, known as a meta-analysis—a statistical procedure in which the results of the five independent trials were added together to mimic one gargantuan trial.

Although I wrote about the update on the front page of the Chicago Tribune, I was the only American reporter at the accompanying Stockholm news conference. The American Cancer Society, and the American College of Radiology, whose members make their living reading mammograms, continued to urge women to begin annual mammograms at age 40.

Now that the task force has changed its recommendation, it seems possible that billions of health-care dollars may have been misspent on mammograms for women under 50—or, according to the Swedish update, under 55—that were either unnecessary, or which caused women needless psychic and physical trauma.

Granted, biostatistics are not easy to understand, and harder to explain to a lay audience. But the current controversy over the task force's report owes much to the media's confusing coverage, some of which has been misinformed, including by TV doctors who ought to know better.

 The confusion has been abetted by the American Cancer Society, whose position appeared to have softened, then hardened again, in recent weeks.

Last month, Dr. Otis Brawley, the cancer society's chief medical officer, was quoted in the New York Times admitting "that American medicine has overpromised when it comes to screening. The advantages to screening have been exaggerated.''

Another Times article quoted Dr. Susan Love, a leading breast surgeon, calling the under-50 question “the third rail” and praising Brawley for questioning the status quo.

“I really don’t think we should be routinely screening women under 50,” Love told the Times. “There’s no data showing it works.”

I wasn't surprised by Brawley's statement, since he had expressed the same view to me when we met at a cancer symposium in Milan in 2003. Following the task force report's release, however, Brawley appeared to change direction, telling The Times that the cancer society had concluded that the benefits of annual mammograms beginning at 40 "outweighed the risks" and that the ACS was sticking by its earlier advice.

"He's trying to save his job," one of Brawley's colleagues said. "He was broiled at home for the interview in which he said that we (the medical establishment) are 'overselling' screening."

In his recent comments, the ACS's Brawley has repeated that regular screening mammograms reduce the incidence of breast cancer in women age 40 to 50 by 15 percent—the same finding as the seven-year-old Swedish update.  It should be noted that before the update, mammography advocates had been claiming that regular mammograms could reduce the risk of dying from breast cancer by a whopping 30 percent. The update knocked that number down, putting the benefit for women age 40 to 74 at 20 percent, a number The Lancet described as "modest," and for women 40-49 at 15 percent.

Thirty percent, 20 percent, and even 15 percent sound like large numbers. Women can be forgiven for asking why a procedure that offers a 15 or 20 percent better chance of surviving breast cancer should be put on the shelf. But even the 15 percent figure is in question.

Dr. Donald Berry, head of biostatistics at the M.D. Anderson Cancer Center in Houston, points out that if the Swedish update is read carefully, the benefit for women 40-50 is really only 9 percent, which is not statistically significant — meaning it could represent the play of chance and not a real advantage.

What Brawley and other mammography advocates flashing across TV screens lately have failed to mention is that the numbers they are flinging around are the relative benefit. Utterly obscured is the number that really matters, the absolute benefit (Brawley did not respond to an email requesting comment).

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