New Evidence Supports Screening in Younger Women

CHICAGO--Medical groups that advocate routine screening mammogra-phyfor women between the ages of 40 and 49 have new ammunition to challengethe NCI's controversial 1993 decision to raise the suggested age for beginningmammography screening to 50 years.

Three studies presented at the annual meeting of the Radiological Societyof North America (RSNA) support regular mammographic screening of youngwomen by showing that it would detect ductal carcinoma in situ (DCIS),which occurs more often in the 40- to 49-year age group, and improve survival.

Annual mammography of younger women admittedly would double the costof breast cancer screening in the United States. However, annual screeningof women in this age group would reduce cancer deaths by 35% to 40% andcost less than other preventive measures, such as cervical cancer screeningwith Pap smears or the use of seat belts and air bags in automobiles, thespeakers said.

W. Phil Evans, MD, medical director, Susan G. Komen Breast Center, BaylorUniversity Medical Center, Dallas, said that women under the age of 50should be screened aggressively for breast cancer because they are morelikely than older women to have DCIS. He reached this conclusion afterretrospectively evaluating 3,734 women with nonpalpable breast lesionswho underwent needle and wire localization and surgical biopsy between1989 and 1995.

Of the 294 cancers found in women 49 years of age and below, 46.6% wereDCIS. In contrast, only 36.7% of the 885 cancers in women over the ageof 50 were DCIS. "We're showing in our study that there is an increasedproportion of DCIS, a potentially curable form of breast cancer, in womenless than 50 years of age, which supports screening of women in this agegroup," Dr. Evans said.

Screening in and of itself has little value unless it affects survivalrates. "It has been argued that breast cancers in younger women aremore aggressive and difficult to detect, and, therefore, regular screeningis not beneficial," said Erik L. Thurfjell, MD, of the Departmentof Radiology, University Hospital, Uppsala, Sweden.

His review of 56,881 women who had mammography up to four times in a6.5-year period showed, however, that there was no significant differencein the stage at diagnosis and that screening for breast cancer was justas effective at improving survival rates for younger women as it was forolder women.

Mammography detected 70% of 671 primary breast cancer tumors in thestudy. Because of regular mammography, the 7-year survival rate for womenunder age 50 was 92%; the survival rate for older women was 87%. "Thebreast cancer survival rate is approximately the same for women betweenthe ages of 40 and 49 as it is for older women in a screening program witha well-documented, high diagnostic quality," Dr. Thurfjell said.

Mammography can have a greater effect on the survival of young womenif it is done every year rather than every 2 years, said Stephen A. Feig,MD, director, Breast Imaging Center, Thomas Jefferson University, Philadelphia.

According to a metaanalysis of the results of seven randomized clinicaltrials, breast cancer deaths among women in this age group would decrease25% with biennial screening, Dr. Feig said. Based on his analysis of thetrial results, breast cancer deaths would fall 35% to 40% if women betweenthe ages of 40 and 49 had an annual mammogram.

Cost in Line With Other Measures

Annual screening mammography of younger women would cost 65% more thanbiennial testing. However, when assessed in terms of the number of yearsof life it would save, the increase in cost would not be as dramatic. "Wefound that annual mammographic screening will cost 40% more per year oflife expectancy saved, but it will save 46% more years of life expectancythan biennial screening," Dr. Feig said.

Using data from the Surveillance, Epidemiology, and End Results (SEER)program, Dr. Feig calculated that annual mammography for women in their40s would cost $8,899 per year of life expectancy gained, and biennialmammography would cost $6,360 per year of life expectancy saved.

While significant, these expenditures are in line with the amounts spenton other commonly accepted prevention programs. "These costs are morethan screening for, say, cancer of the colon, but they are less than screeningfor carcinoma of the cervix, which comes out at $12,000 per year of lifeexpectancy saved," Dr. Feig said.

He added that the costs are much less than the cost per year of lifeexpectancy saved for automobile seat belts and air bags (about $32,000).

The NCI is currently convening a consensus conference to re-evaluateits position on screening of women in their 40s. The Institute changedits position on screening younger women in 1993 because of the lack ofrandomized controlled clinical trials. At a press conference, Dr. Feigwas asked if studies such as the ones presented at RSNA will be enoughto convince NCI of the benefit of mammog-raphy for younger women.

"When the NCI made the decision to drop its former recommendationon screening women in their 40s," he said, "they did not havethe benefit of meta-analysis, which basically adds up the results fromall randomized trials to get a large enough number of women to prove thisthing works." Dr. Feig pointed out that there are now two such metaanalyses,one published in 1995 and another scheduled for publication in the InternationalJournal of Cancer.

"This is totally convincing proof," he said. "It is gettingharder and harder for those who do not believe in screening women in their40s to find a rationale to justify their view."