NCI shows signs of relenting onmammography screening guidelines

May 22, 1996

Swedish study may turn tide for younger womenCracks are appearing in the National Cancer Institute's officialstance on mammography screening for women aged 40 to 49. The NCIplans to convene a conference this fall to reexamine its decisionnot to

Swedish study may turn tide for younger women

Cracks are appearing in the National Cancer Institute's officialstance on mammography screening for women aged 40 to 49. The NCIplans to convene a conference this fall to reexamine its decisionnot to recommend screening for women in their 40s.

The NCI revised its official statement on mammography in 1993,withdrawing its recommendation that women aged 40 to 49 receivescreening mammograms every one to two years (SCAN 12/15/93). Thewithdrawal was widely criticized by the mammography community,which viewed it as a politically motivated move that created confusionamong women and their physicians about the benefits of screeningmammography. The NCI continued to recommend regular screeningfor women over 50, however.

At the time it made its decision, the NCI claimed that recentclinical studies were equivocal about the benefits of screeningmammography for women in the younger age group. In particular,proponents of the NCI's new statement cited the results of theCanadian National Breast Screening Study, which questioned theeffectiveness of mammography for women aged 40 to 49.

The results of that study have been under fire, however, forwhat some critics say is its flawed methodology. More damagingto the NCI's 1993 statement, however, were results presented inMarch at a conference in Sweden that indicated that screeningmammography for women in their 40s can have a major impact inreducing breast cancer mortality.

The study, conducted by prominent Swedish mammographer Dr. LaszloTabar and colleagues at Falun Central Hospital in Sweden, wasa meta-analysis of several large studies conducted in the U.S.,Sweden, and Scotland. It did not include the results of the Canadianstudy.

Tabar's meta-analysis found that screening mammography for womenaged 40 to 49 could result in a decrease in breast cancer mortalityrates as high as 24%. One study of women in Gothenburg, Sweden,found that women in their 40s who were screened had mortalityrates from breast cancer that were 41% lower than a control groupthat was not screened.

In response to Tabar's findings, the NCI has announced that itwill convene a conference this fall to review the institute'sstatement on mammography screening.

"We are calling a consensus conference to look at the evidence,including some new evidence, to see if a group of experts cancome to some conclusion," an NCI spokesperson said.

That's not a moment too soon for Dr. Daniel Kopans, directorof breast imaging at Massachusetts General Hospital in Boston.Kopans has consistently opposed the NCI's decision to withdrawfrom its statement the recommendation for screening women in their40s.

Kopans believes that the NCI in 1993 was relying on an inappropriateanalysis of data, in which there were only one-third the numberof women in clinical trials that would be required to show a statisticallysignificant benefit from earlier screening. In addition, withlonger follow-up, the clinical benefits of earlier screening becomemore apparent, he said.

Kopans, like many others in the mammography community, believesthat the NCI was biased against earlier screening and that theinstitute's original decision to withdraw support for screeningof younger women was political in nature. At the time, the Clintonadministration was preparing the release of its national healthinsurance program, which proposed paying for screening mammographyonly for women aged 50 and over.

The NCI now has a new director, Dr. Richard Klausner, and apparentlya new attitude as well. If the statement is changed, it shouldhelp clear up much of the confusion created by the 1993 statement.

"When the NCI came out with their decision to withdraw supportfor screening women in their 40s, it confused everyone, includingwomen 50 and over," Kopans said. "

It sent a message that said maybe mammography doesn't work atall."