MRI More
Accurately Determines Cancer Spread Into Breast Ducts
Behind the Cancer Headlines®
MRI is better than MDCT for determining if and how far breast cancer has spread into the breast ducts and should be used before patients receive breast conserving therapy, a new study shows.
"Patients have a lower survival rate if their surgical
margins are positive for tumor cells. A positive surgical margin is usually the
result of inadequate resection of the cancer's intraductal
component," said
The study, published in the American Journal of Roentgenology, included 69 patients with proven invasive cancer, 44 of which had an intraductal component, said Shimauchi. MRI correctly identified 33 of the 44 cases, while MDCT correctly identified 27. "MRI revealed the presence of the intraductal component with significantly higher sensitivity (75%) compared to MDCT (61%), Shimauchi said.
"The lesions that were missed by both examinations were the ductal extension type, i.e. the tumor included a dominant mass with an outward extension of cancer cells, with a relatively small ductal component," said Shimauchi. MRI was better able to detect the smaller ductal components than MDCT, she said.
The study also found that both MDCT and MRI "generally
underestimated the length of the intraductal
component," however, MRI was less likely to underestimate the length of
the intraductal component than MDCT. "In our
institution, surgeons err on the side of caution by using a surgical margin
that is 20 mm outside the radiologically determined
tumor margin," said Shimauchi. Underestimation
of the length of the intraductal components by 15 mm
or more was significantly less frequent with MRI (30%) compared to MDCT (55%),
she said.
SOURCES:
American Journal of Roentgenology, August 2006
American Roentgen Ray Society (http://www.arrs.org)