NEW YORK, Jun 16 (Reuters Health) -- Mammograms are important screening
tools for breast cancer. But many women do not know that some tumors detected on
mammograms are not life-threatening. Some of these tumors rarely progress, but
detection of them on a mammogram can lead to unnecessary invasive procedures,
according to a report in the June 17th issue of the British Medical Journal.
Educating women about a non-progressive breast cancer called ductal
carcinoma in situ could help them make decisions about screening and treatment,
the researchers conclude.
This type of cancer is not well understood, but most cases do not seem to
progress, one of the study's authors, Dr. Steven Woloshin, of the Veterans
Administration Medical Center, in White River Junction, Vermont, said in an
interview with Reuters Health. But there is no way to know which ones will
spread, so if this type of cancer shows up on a mammogram, a woman may undergo
surgery to remove the cancer that may turn out to be unnecessary, he said.
In a sample of 479 women in the United States, 99% said that they were aware
that mammograms sometimes give false-positive results, where the scan indicates
cancer but no cancer is present. After a false-positive result, a woman may have
a biopsy, a procedure in which a sample of tissue is removed and tested for
cancer. On average, the women estimated the odds of false-positive results to be
about 20% over the course of 10 years of annual mammograms.
Most women, including those who had had a false-positive mammogram in the
past, said that they were willing to accept the risk of false-positive results,
with 63% willing to tolerate 500 or more false-positives for every life saved
and 37% willing to accept 10,000 false-positive mammograms for every woman
saved, according to the report.
The widespread acceptance of false-positives came as a surprise, according
to Woloshin. "We didn't expect women to be so tolerant of them," he said.
But only 7% of women were aware that mammography can detect slow-growing
breast cancers that are unlikely to progress or threaten life, even without
treatment, the researchers report. In fact, only 6% of women had heard of ductal
carcinoma in situ, either by name or by description.
Once they were informed about this type of cancer, however, many women were
concerned, and most said that they wanted to take this into account before
having a routine mammogram, according to the report. The researchers found that
younger women "were the most interested in this information."
"Education (about mammograms) should perhaps focus less on false positive
and more on the less familiar outcome of detection of ductal carcinoma in situ,"
the team concludes.
