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
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
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."