NEW ORLEANSMagnetic resonance imaging (MRI) of the breast is
more accurate than conventional methods for identifying the extent of
invasive lobular carcinoma, according to a study presented at the
American Roentgen Ray Society annual meeting.
Lobular carcinoma is difficult to detect by mammography because the
tumor cells form a linear array that does not cause architectural
distortion, said Rose E. Heller, MD, a fellow in the Department of
Radiology, Hospital of the University of Pennsylvania, Philadelphia.
This form of cancer may be hidden within the normal breast
tissue on the mammogram and therefore cannot be easily seen,
Dr. Heller said. These tumors account for about 10% of breast cancers
and are often multifocal in nature. Residual disease is more
frequently a problem with lobular carcinoma than with infiltrating
Dr. Heller and her colleagues studied 31 women with lobular
carcinoma, 32 to 69 years old, who were enrolled in various protocols
at their institution: 10 were studied following excisional biopsy, 9
had a positive screening mammogram, 8 had palpable abnormalities, 1
had a positive axillary lymph node, and 3 were excluded due to lack
of clinical follow-up. Contrast-enhanced MR images were compared with
mammography and ultrasound results, and correlated with pathologic
findings after excision or mastectomy.
Tumor extent on MR imaging correlated with pathologic tumor extent in
89% of the cases, Dr. Heller said. In two cases, MR imaging
overestimated disease extent, and, in one instance, disease extent
MR imaging alone accurately detected tumor extent in 20 of the 28
cases (71%), whereas in only one case was tumor extent determined
accurately by mammography alone. Both MRI and mammography identified
tumor extent in 5 cases.
Only 12 women had ultrasound studies performed, but in 8 cases,
ultrasound underestimated tumor extent. In 4 cases, both MR imaging
and ultrasound were able to accurately assess tumor extent.
Clinically, MR imaging upstaged 20 of the 28 patients. While 6 women
went directly to mastectomy, 13 opted for wider excision, with 8 of
them ultimately undergoing mastectomy. For 4 patients, MR imaging
would have predicted the need for mastectomy initially. Thus, this
procedure could be used to guide surgical planning.
Both Dr. Heller and one of her collaborators, Susan Orel, MD,
commented that MR imaging could be used to plan the fastest and most
accurate treatments for women with lobular breast cancer.
Although our work needs to be expanded, the results are
compelling for this small group, Dr. Heller said.