New research published online today (Monday, May 16) in The Lancet has found that magnetic resonance imaging (MRI) is almost twice as sensitive as X-ray mammography (XRM) in detecting breast cancer in women at high genetic risk.
The findings are the result of a national study (MARIBS) funded by the Medical Research Council, involving a number of centres across the UK, including the Department of Radiology at the University of Aberdeen.
Professor Fiona Gilbert, Professor of Radiology and Roland Sutton Chair of Radiology, at the University of Aberdeen, is co-author of the research paper and part of the Steering Committee involved in the study.
Past research has highlighted that around 2% of breast cancer is due to the recently discovered breast cancer gene mutations BRCA1 and BRCA2. Women with one of these gene mutations come from families where there is a strong family risk of breast cancer, and more than half of them will develop breast cancer by the age of 70.
Annual mammograms are offered to women with these gene mutations to allow early identification and treatment of tumours. However, as women below the age of 50 often have dense breasts, mammography is not always very effective at detecting tumours.
The MARIBS study looked at whether MRI would be more helpful in detecting tumours within these groups of women.
Professor Gilbert explained: “The Department of Radiology undertook this study in collaboration with the Medical Genetics Department at the University of Aberdeen and were one of a number of centres involved in the research.
“We have actively been involved in assessing the risk from breast cancer and establishing whether MRI is better than x-ray to allow early identification and treatment of tumours.
“The University recruited for this study a small number of families from across the north-east who are thought to be gene carriers and therefore are at high-risk. They have a very strong family history of four or more family members who have had breast cancer and these are individuals who we term as high risk and who may be a gene carrier.
“What we found from the results of the study is that MRI is better than using X-ray mammography in detecting breast cancer in women at high genetic risk.”
The MARIBS study showed that XRM managed to identify only 40% of the tumours in women at high genetic risk, whereas MRI pinpointed 77%. It was found that by combining both XRM and MRI screening methods, 94% of tumours would be detected. MRI screening was shown to be particularly effective for women known to carry the BRCA1 gene mutation, detecting 92% of tumours in women carrying this gene, whereas XRM only detected 23%.
Recruitment for the study took place at 22 radiology and genetic centres throughout the UK. In total 838 women at high risk of breast cancer, based on testing, family history or affected relatives, were enrolled onto the study between August 1997 and May 2004. The women, aged 35 to 49 years, were offered annual MRI and XRM for between two and seven years. The results for each were then compared with their true cancer status, assessed either by pathological examination or by the absence of cancer at the following year’s examination.
Each case where a participant received both an XRM and MRI in the same year was analysed, amounting to a total of 1,881 screening years. From this number, 35 cancers were detected in total, 19 were detected by MRI alone, six by XRM alone, eight cancers were detected by both methods, and two weren’t detected by either method.
Professor Martin Leach, of The Institute of Cancer Research and the Royal Marsden NHS Foundation Trust, is principal investigator for the trial, and said: “This study demonstrates that MRI screening is almost twice as sensitive as traditional X-ray mammography in identifying tumours in women of this age group at high genetic risk. As this study was carried out on a countrywide scale, the results represent a realistic assessment of how effective the method would be if it were implemented as a service.”
Professor Gilbert added: “If individuals are worried in any way by the results from the study and think they fall into the high risk category, I would recommend that they go and see their own general practitioner who can then assess the individual’s family history and the level of risk they are at.”
Further work will continue the study in analysing the images in order to look at features in the gene carriers.