Combined MRI and X-ray mammography best way to detect breast cancer
10 June 2005
Annual screening, using magnetic resonance imaging (MRI) and X-ray
mammography, is the best way to detect breast cancer in women that have a
high genetic risk of the disease, say researchers at The Institute of Cancer
Research, London.
Women who have mutations in the BRCA1 and BRCA2 genes have a high risk of
developing breast cancer, often at an early age. Regular mammograms are
offered to high-risk women to allow for the early identification and
treatment of tumours. However, because these women are of a young age, they
often have denser breasts, which affect the ability of mammography to detect
disease.
Martin Leach and colleagues looked at whether MRI would be more effective
than mammography in detecting breast tumours in high-risk women. Between
August 1997 and May 2004, they recruited around 650 women at high risk of
breast cancer, from 22 radiology and genetic centres throughout the U.K. The
women, aged 35 to 49 years, were offered annual MRI and X-ray mammography
for between 2 and 7 years.
Reporting online May 16, 2005, in The Lancet, Leach's team found that MRI
was nearly twice as sensitive as X-ray mammography in detecting breast
cancer in women that have a high genetic risk of the disease. X-ray
mammography identified 40% of the tumours in the women, while MRI detected
77%. However, when mammography and MRI were combined, 94% of tumours were
picked up in the women.
The researchers also found that MRI screening was particularly effective
for women known to carry the BRCA1 gene mutation, detecting 92% of tumours
in women carrying this gene whereas X-ray mammography only detected 23%.
Leach told The Lancet, "Our results, taken with the two other major
prospective studies, suggest that MRI screening is more effective than
mammography in this high risk group, and combining the methods is very
effective. Our study also showed that MRI is of most benefit in carriers of
BRCA1 mutations."
In an accompanying Comment, Ellen Warner of Toronto-Sunnybrook Regional
Cancer Center, Ontario, Canada, pointed out, "Although there is now
unequivocal evidence that surveillance MRI is significantly more sensitive
than mammography for women at high hereditary risk and detects cancers at an
earlier stage, it is not yet known whether it will lower mortality in this
population."
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