CHICAGO--Medical groups that advocate routine screening mammogra-phy for women between the ages of 40 and 49 have new ammunition to challenge the NCI's controversial 1993 decision to raise the suggested age for beginning mammography screening to 50 years.
Three studies presented at the annual meeting of the Radiological Society of North America (RSNA) support regular mammographic screening of young women 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 cost of breast cancer screening in the United States. However, annual screening of women in this age group would reduce cancer deaths by 35% to 40% and cost less than other preventive measures, such as cervical cancer screening with Pap smears or the use of seat belts and air bags in automobiles, the speakers said.
W. Phil Evans, MD, medical director, Susan G. Komen Breast Center, Baylor University Medical Center, Dallas, said that women under the age of 50 should be screened aggressively for breast cancer because they are more likely than older women to have DCIS. He reached this conclusion after retrospectively evaluating 3,734 women with nonpalpable breast lesions who underwent needle and wire localization and surgical biopsy between 1989 and 1995.
Of the 294 cancers found in women 49 years of age and below, 46.6% were DCIS. In contrast, only 36.7% of the 885 cancers in women over the age of 50 were DCIS. "We're showing in our study that there is an increased proportion of DCIS, a potentially curable form of breast cancer, in women less than 50 years of age, which supports screening of women in this age group," Dr. Evans said.
Screening in and of itself has little value unless it affects survival rates. "It has been argued that breast cancers in younger women are more aggressive and difficult to detect, and, therefore, regular screening is not beneficial," said Erik L. Thurfjell, MD, of the Department of Radiology, University Hospital, Uppsala, Sweden.
His review of 56,881 women who had mammography up to four times in a 6.5-year period showed, however, that there was no significant difference in the stage at diagnosis and that screening for breast cancer was just as effective at improving survival rates for younger women as it was for older women.
Mammography detected 70% of 671 primary breast cancer tumors in the study. Because of regular mammography, the 7-year survival rate for women under age 50 was 92%; the survival rate for older women was 87%. "The breast cancer survival rate is approximately the same for women between the ages of 40 and 49 as it is for older women in a screening program with a well-documented, high diagnostic quality," Dr. Thurfjell said.
Mammography can have a greater effect on the survival of young women if 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 clinical trials, breast cancer deaths among women in this age group would decrease 25% with biennial screening, Dr. Feig said. Based on his analysis of the trial results, breast cancer deaths would fall 35% to 40% if women between the 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 than biennial testing. However, when assessed in terms of the number of years of life it would save, the increase in cost would not be as dramatic. "We found that annual mammographic screening will cost 40% more per year of life expectancy saved, but it will save 46% more years of life expectancy than 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 their 40s would cost $8,899 per year of life expectancy gained, and biennial mammography would cost $6,360 per year of life expectancy saved.
While significant, these expenditures are in line with the amounts spent on other commonly accepted prevention programs. "These costs are more than screening for, say, cancer of the colon, but they are less than screening for carcinoma of the cervix, which comes out at $12,000 per year of life expectancy saved," Dr. Feig said.
He added that the costs are much less than the cost per year of life expectancy saved for automobile seat belts and air bags (about $32,000).
The NCI is currently convening a consensus conference to re-evaluate its position on screening of women in their 40s. The Institute changed its position on screening younger women in 1993 because of the lack of randomized controlled clinical trials. At a press conference, Dr. Feig was asked if studies such as the ones presented at RSNA will be enough to convince NCI of the benefit of mammog-raphy for younger women.
"When the NCI made the decision to drop its former recommendation on screening women in their 40s," he said, "they did not have the benefit of meta-analysis, which basically adds up the results from all randomized trials to get a large enough number of women to prove this thing works." Dr. Feig pointed out that there are now two such metaanalyses, one published in 1995 and another scheduled for publication in the International Journal of Cancer.
"This is totally convincing proof," he said. "It is getting harder and harder for those who do not believe in screening women in their 40s to find a rationale to justify their view."