Diagnostic imaging  

Magnetic resonance imaging can help predict recurrence of breast cancer

19 June 2005

A US study of breast cancer patients has found that measurement of breast tumour volume before, during and after chemotherapy using magnetic resonance imaging (MRI) can help predict whether a patient’s cancer will return.

The study, performed at the University of California-San Francisco, of 58 breast cancer patients found that the best way to predict a patient's recurrence-free survival is to review the initial MR examination (before the patient has chemotherapy) and the final MR examination (after chemotherapy has been completed). “Initial tumour volume was a strong predictor of recurrence free survival. Of the women who had tumour volumes of 33 cm3 or less on the initial MR exam, 93% remained disease free after two years, compared with 70% of the women with larger tumours. This speaks strongly for the value of early detection,” said Savannah C. Partridge, PhD, now an assistant professor of radiology at the University of Washington, Seattle.

“The change in tumour volume with treatment was also a valuable predictor,” said Dr. Partridge. “We found that the group of patients who had a 50% or greater reduction in MRI tumour volume when comparing the first MR examination to the last had a better recurrence-free survival rate (87% remained disease-free after two years) than those with less tumour shrinkage during chemotherapy treatment (64% were disease-free after two years), irrespective of their initial tumour volumes,” she added.

One patient with a large focal mass showed a substantial decrease in tumour volume on MRI during treatment, and continues to be disease-free 40 months after surgery. In contrast, a second patient, with a more diffuse mass, showed an increase in tumour volume on MRI during treatment that was not detected by clinical examination. Her disease returned eight months after surgery, said Dr. Partridge.

Most often, MRI is used to measure the tumour's diameter, said Dr. Partridge. “This study shows that while measuring tumour diameter is useful for staging, volume is preferable for monitoring treatment because 3D volume measurements can more accurately capture the extent of irregularly shaped tumours, multifocality and diffuse shrinkage of lesions during treatment,” she said. “It is important that an accurate and validated tool be used for calculation of 3D tumour volume from MRI images,” she noted.

Physicians now typically evaluate treatment response by clinical exam and pathology. “But unlike pathology, early changes in tumour volume can potentially be assessed by MRI at a time when chemotherapy regimens can still be modified. Our study showed that MRI measurements of breast tumour volume can help predict recurrence-free survival. We are encouraged by these results and anticipate that monitoring tumour response by MRI will help us to better tailor treatment strategies for individual patients. A larger multi-center study is currently underway to see if MRI can determine if chemotherapy is working early enough for treatment to be changed,” she said.

The study appears in the June 2005 issue of the American Journal of Roentgenology. AJR Jun 2005;184:1774-1781
Website: www.ajronline.org

Source: American Roentgen Ray Society (ARRS)
Website: www.arrs.org/

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