New Statistical Model Could Cut Needless Breast Biopsies

FRIDAY Dec. 5, 2008 -- A new statistical model may help radiologists better determine whether a breast lesion detected by MRI is malignant or benign, something that could help prevent unnecessary biopsies, say U.S. researchers.

They reviewed almost 2,600 breast MRI exams conducted over four years at the Seattle Cancer Care Alliance and identified three important categories of patient and lesion characteristics that, when used in combination, could predict the likelihood of cancer. The three are: the reason a woman is having a breast MRI; the size of the lesion; and the lesion enhancement pattern from the MRI contrast dye.

Lesions most likely to be malignant were: in women undergoing MRI to look for additional malignancy after new breast cancer diagnosis; lesions larger than one centimeter; and those whose enhancement quickly faded (called washout).

Lesions most likely to be benign were: in women being screened because they're considered to be at high risk for cancer; small lesions; and those with increased enhancement over time.

"If the lesions had those three characteristics, the likelihood of malignancy was 1 percent. This is so close to zero that rather than doing a biopsy, we could instead follow the patient by doing another MRI in a few months, or we may not need to do any additional testing," Dr. Wendy DeMartini, an assistant professor in the University of Washington School of Medicine, said in a Fred Hutchinson Cancer Research Center news release.

Futher study is required before this statistical model can be validated for use as standard practice.

"This is a preliminary model. Future work will look at additional patient and lesion features, and in the longer term, we need to examine lesions from multiple practice sites," DeMartini said. "Our goal is to identify a group of lesions that we currently recommend for additional tests where the likelihood of cancer is so low that we can safely avoid additional testing."

The research was presented Sunday at the Radiological Society of North America annual meeting, in Chicago.

More information

The American Cancer Society has more about breast biopsy.

Posted: December 2008


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