Following a week of controversy, support for mammography has been reconfirmed both in the pages of The Lancet and by the National Cancer Institute (NCI).

A new look at the most widely accepted evidence on the value of mammography has concluded that it cuts breast cancer deaths by more than half in women 55 and older, and by almost one-third in women 45 to 54, according to a report in the Feb. 2 issue of The Lancet (Vol. 359).

The life-saving benefit becomes clear once screening programs have been going on for a few years, said lead author Olli S. Miettinen, MD, PhD, professor of epidemiology and biostatistics at McGill University in Montreal, Quebec, Canada.

"Screening does not have an immediate effect; the deaths that are prevented by screening are in the future, years away [from the beginning of screening]," noted Miettinen and colleagues.

If that undisputed fact had been kept in mind more consistently as mammography studies were reviewed recently, a lot of confusion among the public and doctors might have been prevented, the authors wrote.

An American Cancer Society (ACS) cancer screening expert agrees.

"You need to allow for adequate follow-up in these trials to see a measurable benefit from early detection," said Robert Smith, PhD, director of cancer screening for the American Cancer Society (ACS).

That's because breast cancer typically does not cause death in the first few years after diagnosis, Smith noted.

Roughly the same number of women getting screened and not getting screened will develop breast cancer, Smith said.

But those getting screened are much more likely to survive their cancer or to live longer, because their cancer is much more likely to be discovered in its earliest, most treatable stages, he added.

But what's important in judging scientific evidence is not just one review or study, but all the evidence, noted Smith.

"The totality of the evidence from the randomized trials of breast cancer screening is persuasive that breast cancer screening saves lives, and women should not have their confidence shaken in the use of this important test," Smith concluded.

In a related event, 10 nationally recognized public health groups placed an ad in the Jan. 31 edition of the New York Times calling attention to the large body of evidence showing the life-saving value of mammography (see full text of ad below).

The new Lancet article affirming mammography's value comes a few days after scientists producing cancer-related information for the National Cancer Institute (NCI) were quoted in a Jan. 24 New York Times article as saying they would likely re-write some information to reflect their new doubts about mammography's value.

However, in a statement released Jan. 31, the NCI confirmed its support of mammography by recommending that:

• Women in their 40s should be screened every one to two years with mammography.
• Women aged 50 and older should be screened every one to two years.
• Women who are at higher than average risk of breast cancer should seek expert medical advice about whether they should begin screening before age 40 and the frequency of screening.

The statement also said that, "One of its highest priorities will be the monitoring and evaluation of new data on mammography from numerous studies now underway which will supplement the data from clinical trials."

The story in the New York Times quoted the NCI writers as saying doubts were raised by two Danish researchers, Ole Olsen and Peter C. Gotzsche, in an earlier Lancet article.

Olsen and Gotzsche wrote in the Lancet in 2000 and in 2001 that only two of the seven major studies generally accepted as showing that mammography saves lives by detecting breast cancer early were well-designed enough to rely on.

One study showed a life-saving benefit but the other didn't, and if the numbers from the two studies were looked at differently — added together — the life-saving benefit disappeared, said the Danes.

The new Lancet article takes a closer look at the Malmo study — one of the two studies regarded by the Danish writers as being of acceptable quality.

The Danish reviewers focused on the fact that during the 10 years of the Malmo study, 66 women not screened died, and 63 who were screened with mammography died.

That's not enough of a difference to justify mammography screening, the Danes said.

But Miettinen's group pointed out that the Malmo study authors actually reported a 30% drop in breast cancer deaths after the first six years of that trial.

And the Miettinen group's analysis of the Malmo study found even larger differences after screening programs had been going for a while.

Miettinen noted that when scientists don't consider the lag time necessary before any mammography benefits can show up, the result "is not only useless; it misleads public policy and confuses the public and physicians."

We, the undersigned, representing a broad spectrum of concerned health organizations, are responding to coverage in the media and the resulting public discussion questioning the value of mammography. This discussion has been stimulated by a recent report published in the British medical journal, The Lancet, which concluded there was no scientific support for breast cancer screening with mammography.

Women and their healthcare professionals should know that numerous independent expert groups in the U.S. and Europe have repeatedly subjected the world's major clinical studies of mammography to careful scientific scrutiny, and also have carefully evaluated the analysis published in The Lancet. While the existing studies of mammography screening have known limitations and even some flaws, the evidence as a whole solidly supports reduced breast cancer mortality rates due to mammography screening. Early breast cancer detection means a greater chance for successful treatment and a greater range of treatment options.

We have grave concerns that these public debates have already begun to erode the confidence in mammography that has been built up over the past two decades. While mammography is not a perfect tool, it is effective and has contributed significantly to the declines in breast cancer mortality since 1990. In fact, there will be many thousands fewer breast cancer deaths among U.S. women this year due to the combined progress we've made in early detection and improved therapy. If women are dissuaded from getting regular mammograms, lives will be lost.

We strongly urge women to continue to follow the advice of their physicians and the leading medical organizations. Our organizations will continue to monitor new scientific research in order to offer the best advice to women and their physicians.

This letter is cosigned by the following organizations:

American Academy of Family Physicians
American Cancer Society
American College of Physicians-American Society of Internal Medicine
American College of Obstetricians and Gynecologists
American College of Preventive Medicine
American Medical Association
Cancer Research Foundation of America
National Medical Association
Oncology Nursing Society
Society of Gynecologic Oncologists

For more information about the early detection of breast cancer, call 1-800-227-2345.