***** Women Risk False Positive on Mammogram *****
By Maggie Fox, Health and Science Correspondent
WASHINGTON (Reuters) - Some women who try to do the right thing by getting regular mammograms may have a 100 percent chance of getting scared by a false positive result, researchers said on Tuesday.
They said the more often a woman has a mammogram, the greater her chance of having a frightening false positive. But there are ways to screen out the factors affecting these odds so women can be reassured, Dr. Cindy Christiansen of the Boston University School of Public Health and colleagues, said.
``What we are hoping is that women realize this is common,'' Christiansen, whose findings are published in this week's Journal of the National Cancer Institute, said in a telephone interview.
``In our study, 43 percent of the women were expected to experience a false positive by the ninth mammogram. The majority of times it does not mean cancer.''
But there are ways that doctors and technicians who do the scans, which can detect breast cancer when it is at its earliest stages and most curable, can reassure women so they do not panic, Christiansen said. Only one out of 20 positive results on a mammogram actually are due to cancer.
Ironically, it is the women who go and have mammograms regularly who are most at risk of having the test turn up something a doctor or technician thinks looks suspicious and needs further checks to determine if it is cancerous.
``The risk of having a false positive, if you continue to go by the guidelines of having a mammogram every year (after the age of 50), goes up for having a false positive. This true for any screening or diagnostic test,'' Christiansen said.
Any Test Carries Risk Of False Positive
That is because any test carries the risk of a false positive, a risk that is multiplied for every time the test is taken.
``The cumulative risk of experiencing a false positive mammogram over nine screening mammograms can be as low as 5 percent for women with characteristics that make them at low risk or as high as 100 percent for women with multiple high-risk factors,'' the researchers wrote.
For her study, Christiansen gathered data on more than 2,200 women who got mammograms. Ironically, the older a woman was, the less likely it was she would have a false positive.
``Younger women have an increased risk, those who use estrogen, a woman who had a previous breast biopsy and those with a previous history of breast cancer,'' she said.
There are also factors concerning the test itself and the technician who does it. ``The longer the time between mammograms and if a radiologist is not able to compare the current mammogram to a previous one increases the risk of a false positive,'' Christiansen said.
``One thing a woman can do to reduce her risk is to either go back to the clinic that she went to before or to take her films with her, so if there is a smudge they can see something was also there last year.''
Some technicians also are extra cautious and produce more false positives. ``We can encourage women to talk to radiologists and ask the question 'how often do you call people back (for more tests)?','' Christiansen said.
``In other words, how nervous do I need to be?''
She also suggested that doctors, when they do get a suspicious reading on a mammogram, make other checks such as an ultrasound right away so that women do not worry. |
