It’s human nature. We will adopt any excuse in order to avoid the unpleasant.
In late 2001, two Danish researchers gave women another excuse to avoid mammograms, saying that mammograms are “unjustified,” because there is no reliable evidence that they save lives (The Lancet, October 20, 2001).
Unfortunately, this information was rapidly picked up and disseminated by the media. Since then, health experts have battled to undo the damage done by the widespread publication of what most health experts feel is erroneous information.
Mammography Studied Since the 1960s
After studies in the 1960s and 1970s involving more than 300,000 US women showed mammography could detect breast tumors too small to be found any other way, widespread mammography screening began in the US in the mid-1980s.
Between 1988 and 1999, seven other large trials involving about 500,000 women solidified widespread agreement in the medical community of mammography’s value.
Danish Researchers Say Studies Flawed
But Danish researchers Ole Olesen and Peter Gøtzsche said none of the seven trials were very good, and the two that were adequate showed no benefit to mammography.
“There is no reliable evidence that screening decreases breast cancer mortality,” the researchers concluded.
Olsen and Gøtzsche noted death rates from breast cancer hadn’t yet dropped in Sweden, even though mammography was being used there.
Few Agree With the Researchers’ Conclusions
The researchers’ first report met with criticism from cancer experts and organizations.
Along with the 2000 article, Lancet published a critique (Vol. 355, No. 9198: 80-81) in which commentator Harry J. de Koning questioned the researchers’ reasoning, methods, and results.
De Koning noted Sweden’s mammography program might not have been going on long enough to produce a drop in breast cancer death rates by 1999, but United Kingdom and Finland breast cancer death rates were beginning to drop after longer term mammography programs there.
Cancer organizations such as the American Cancer Society and the National Cancer Institute and cancer doctors dismissed the 2000 report and confirmed the value of mammography in early detection of breast cancer.
“The Danish researchers made any number of arbitrary decisions and arguable judgments about the quality of the trials, “ explains Robert A. Smith, PhD, director of cancer screening for the American Cancer Society in Atlanta.
The researchers based their conclusions on two studies alone, which, according to Dr. Smith, “is just a fraction of the world data.”
And, as reported in an editorial accompanying the article in The Lancet, the editors at the Nordic Cochrane Center, where both researchers work, distanced themselves from the report, saying it had not been through the rigorous review for which their institution is known.
Researchers Re-do Report
Given all the criticism, last year the Danish researchers reanalyzed their findings. To no one’s surprise, they stood by their original conclusion that mammography doesn’t save lives.
And, they said, their review now also showed mammography may lead to more aggressive treatment than necessary for some women.
This is what made news and led to the latest controversy about the effectiveness of mammography.
What is important to note, however, is that this most recent report did not contain any new research and was based on their original paper, which was widely criticized by those in the medical and public health communities.
Researchers Conclusions Again Rejected
The 2001 Lancet article met with much the same rejection from cancer experts as its predecessor.
Smith notes that in both reports the researchers labeled, based on dubious criteria, five of the seven studies as being of poor or flawed character, leaving them with two which they said together showed no benefit, even though one didn’t and one did.
Experts summarily dismissed that process after the original report, says Smith.
The researchers’ institution also disagreed with the report’s conclusions, refusing to publish it as written, resulting in one version published in The Lancet, and a different version by the institution’s library.
Mammography’s Value Reaffirmed
Smith notes that the reason more than 80% of US women have had a mammogram is because expert groups supported by leading medical organizations have also looked very carefully at the available evidence, and concluded that mammograms are an important part of women’s health care and reduce deaths from breast cancer.
Women should continue to be screened according to the appropriate ACS guidelines, Smith says.
Smith also noted, “Over the past 30 years, mammography has come under constant, aggressive scrutiny. The clinical trials of mammography have been analyzed, re-analyzed, and subjected to numerous overview and meta-analyses by many separate investigators and expert groups.
“It is highly unlikely that all of these carefully performed studies are wrong, and this one is right, especially given the numerous flaws that were identified in the previous analysis,” Smith says.
Smith also observes that the Swedish Board of Health has independently scrutinized the five studies of mammography performed in that country, and thoroughly reviewed all of the information regarding the women who were screened.
In May 2001, Smith and his colleagues published a 29-year follow-up study of women in two counties in Sweden, which found a 63% decrease in deaths from breast cancer in women age 40 to 69 since the introduction of mammography in that area.
“The overwhelming weight of scientific opinion — based on the overwhelming weight of scientific evidence — is that early detection saves lives by providing an opportunity to treat tumors at a more favorable stage, resulting in better outcomes for women with breast cancer,” he says. “That’s the value of mammography, and from a scientific standpoint, the evidence is beyond dispute.”
