Saturday, 30 June 2012

False-positives deterring women from mammogram follow-ups

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mammograph“It is possible that [further invasive testing] upsets people and they go, ‘I don’t want that to happen again’, and so they don’t return.”—Professor Fritschi. Image: iStockFALSE-positive mammogram results deter women from attending rescreening, a study published in the Medical Journal of Australia has found.

The study, conducted by BreastScreen WA states 67.6 per cent of women who received a false-positive mammogram result were less likely to return for a rescreen.

This was compared to 70.7 per cent of women who were given a true-negative result.

In WA, about 44 in 1000 women screened by BreastScreen WA receive a false-positive screening result.

The recall rates for follow-up assessments were fewer than ten per cent for women having their first mammogram and fewer than five per cent for women having a subsequent examination.

UWA Epidemiology Professor Lin Fritschi, who oversaw the statistical analysis of the study, says women who have a false-positive mammogram are put through several tests which could result in future deterrence from screening.

 “It is possible that [further invasive testing] upsets people and they go, ‘I don’t want that to happen again’, and so they don’t return,” Professor Fritschi says.

“I think it is really important when women come in to have their further assessment... that they are told [if they are ok] ‘you are ok, that’s great news, don’t forget to come back for your screening in two years’.

“It’s very important we keep looking because they can develop cancer in the future, so it’s very important [the patient] continues to do their screening.”

Professor Fritschi says any test may have false-positive and false-negative results and the mammogram screening process was not always definitive.

“We can’t do a diagnostic test on everybody,” she says.

“There’s no point in just taking out lots of pieces of biopsy or something from somebody’s breast just to see if they’ve got cancer.

“That’s why we have a test that at least pulls out people who are more likely to have cancer and then further tests only them.”

University of Sydney Screening and Test Evaluation Program research fellow and breast cancer expert Nehmat Houssami says it is important false-positive mammogram screening results are minimised.

“False-positive screening is considered a ‘harm’ from screening,” Ms Houssami says.

“For most women (aged 50-69 years) this harm is outweighed by the potential benefit of mammography screening.”

Ms Houssami says “early detection of breast cancer through mammography screening has been shown to reduce breast cancer deaths (approximately 25 per cent reduction in breast cancer mortality relative to women who do not have screening).”

The authors concluded “mammographic population screening services should keep their false-positive result rates low, to prevent women from being deterred from screening.”

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