Will imaging replace biopsies in cases of suspected breast cancer?
Statistically, about one in 20 women who undergo mammography screening can expect a suspicious finding. If further tests indicate a possibility of cancer, the screening physician recommends taking a tissue sample, or biopsy. Nearly 35,000 women every year face this situation. ‘However, in only about 17,000 of these cases is a malignant tumour actually found,’ says Dr. Sebastian Bickelhaupt, a radiologist at the DKFZ who has been investigating the use of advanced MR imaging in diagnosing breast cancer. ‘We have been looking at advanced imaging technologies as a potential way of reducing the number of invasive tissue examinations.’
In a mammogram, which examines the breast using X-rays, it is often impossible to distinguish benign from malignant abnormalities in tissues and thus exclude the existence of a malignant tumour to the physician’s satisfaction. If the situation can’t be clarified by further testing, such as an ultrasound examination, an invasive biopsy must be performed.
The DKFZ radiologists have optimized a method called diffusion-weighted magnetic resonance imaging (MRI) specifically for use in these cases. ‘Diffusion-weighted MRI is a special technique that allows us to see the movement of water molecules in tissues,’ explains Professor Heinz-Peter Schlemmer, head of Radiology at the DKFZ. ‘Since tumours strongly reduce the movement of these molecules, we decided to examine the potential of our optimized breast MRI for deeper investigations of suspicious findings, in hopes of avoiding an unnecessary biopsy.’
This idea led the DKFZ researchers to plan a study in close collaboration with the office-based physicians in Dr. Wolfgang Lederer’s team at Heidelberg ATOS Klinik and Dr. Heidi Daniel’s team at the Radiology Centre Mannheim, who routinely conduct mammography screenings. If a mammography shows a suspicious lesion, the patient is invited to the Radiology Centre Mannheim for further testing and, as a rule, also for biopsies.
‘For our study, we asked affected women if they were prepared to have an optimized breast MRI prior to the biopsy,’ Daniel explained. ‘We were surprised to get such a high rate of participation that we could proceed with the study quickly,’ Lederer adds. ‘We owe our thanks to the many participants,’ Lederer adds.
The DKFZ radiologists compared the MRI images with results from the biopsies. ‘Within the first 50 cases we investigated, we were already thrilled,’ says Bickelhaupt. ‘Adding the step of optimized breast MRI enabled us to classify over 90 percent of the suspicious findings correctly. That’s an enormous improvement over the 50-percent rate achieved by a combination of mammography and a subsequent ultrasound examination.’
In Schlemmer’s opinion, this does not mean that breast MRI is ready to replace screening mammography. ‘The positive results of our study are based on using MRI in combination with other tests. X-ray mammography also detects minute microcalcifications that indicate non-invasive breast cancer (DCIS), which do not appear in MRI.’ According to Schlemmer, optimized breast MRI is most suitable for clarifying a suspicious finding. A biopsy would only be required if the MRI indicates a high likelihood for a positive finding.
The German Cancer Research Centrehttp://tinyurl.com/hh7zsnl