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 The finding, in a study of 261,767 Chicago-area women in the journal
Cancer Epidemiology, Biomarkers and Prevention, highlights an
unintended consequence of such false alarms, known as false
positives.
In cases where a mammogram was recommended every year, women who had
an unfounded scare tended to delay their next test by an additional
13 months compared to a three- to six-month delay for women whose
tests had come out negative.
That, in turn, can affect a woman's chances of survival if breast
cancer is subsequently diagnosed.
Among women who had not experienced a false alarm, their odds of
being diagnosed with an advanced tumor were 0.3 percent. The odds
for a woman who had experienced a false alarm were slightly but
significantly higher at 0.4 percent.
Some women never showed up at all, but the researchers couldn't
determine whether they gave up on the breast cancer screening or
simply had it done elsewhere.
"It's a delicate balance," chief author Firas Dabbous of Advocate
Lutheran General Hospital in Park Ridge, Illinois, told Reuters
Health. "We want to detect tumors when they are present but we don't
want to overburden women with a lot of false positives and a workup
that is not needed."
Debates over how often women should get mammograms often focus on
whether false positives - which can cause women to experience
anxiety as well as painful and expensive extra testing, including
biopsies – represent a harm that outweighs the benefits of
screening.
"The delays the authors observed were significant," Robert Smith,
vice president for cancer screening at the American Cancer Society,
told Reuters Health by email. "If these findings can be validated in
other studies, then it suggests that extra attention should be
dedicated to insuring that women with false positive findings are
reminded to return to annual or biennial screening with sufficient
notice and multiple reminders."
Being told that a breast X-ray has uncovered something suspicious is
always stressful, even though most women are also told that, in the
vast majority of cases, there is no problem.
Women who have a mammogram have a chance as high as 1 in 10 of
getting a false positive. In fact, a woman who has an annual
mammogram has a 50-50 chance of having one false positive every
decade. An estimated 7 percent to 17 percent of those will require a
biopsy.
Previous studies that have tried to assess how false positives
affect the willingness to have a future mammogram have produced
mixed results.
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"Most U.S. studies have shown either greater adherence to screening
recommendations after a false positive, or no difference, whereas
studies done in Europe have shown screening rates somewhat lower
than women who have true negative results," Smith said.
The Dabbous team looked at 741,150 screening mammograms done at a
large healthcare organization.
In 12.3 percent of the cases, there was something suspicious but it
turned out to be a false alarm.
During the three years after that initial mammogram, 77.9 percent of
the women with a false positive result had a subsequent mammogram
compared to 85.0 percent of the women who had not experienced a
false alarm.
Biopsies seemed to play a significant role in whether a woman came
back for another mammogram. Compared to patients who had received a
false positive and simply received additional imaging, women who
also got a biopsy were 19 percent less likely to come back for a
regular mammogram.
It’s not known if the false positive experience prompted some women
to give up on mammograms, said Dabbous, who is manager of patient
centered outcomes research at Advocate's Russell Institute for
Research and Innovation.
The lesson for women remains "to encourage women to adhere to
mammography screening and come back on time because this is the only
tool that we have that is literally working," Dabbous said. "Yes, it
has some limitations. But it's increasing the survivability of the
woman through early detection."
SOURCE: http://bit.ly/2kLmR2s Cancer Epidemiology, Biomarkers and
Prevention, online February 9, 2017.
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