According to the National Cancer Institute, more than 250,000
new cases of invasive and in situ breast cancer will be detected
this year, but nearly 1.2 million breast biopsies will be
performed.
1
That means that nearly 80% of all biopsies will be performed on
women without cancer. The fact that the vast majority of these
procedures are performed on healthy women emphasizes the need for
these biopsies to be as minimally invasive as possible, while
maintaining the highest degree of diagnostic accuracy.
With open surgical biopsy, women are subjected to the risks of
general anesthesia; require significant recovery time, with time
lost from work and family; and are faced with significant pain and
possible breast disfigurement. In addition, open procedures can
leave scarring within the breast tissue that can interfere with
future mammographic images.
Minimally invasive image-guided needle biopsy procedures--both
core-needle and vacuum-assisted--offer additional options for
specimen acquisition that provide many benefits to the patient and
the practitioner. Needle biopsies can be performed with only local
anesthesia, require significantly shorter procedure and recovery
time, cause less patient discomfort, and do not have a risk of
permanent scarring.
A study presented at the 2001 American Roentgen Ray Society
annual meeting in Seattle, WA highlighted some of the advantages of
the minimally invasive biopsy procedure.
2
The 2-year study, conducted at Brigham and Women's Hospital in
Boston, MA, found that when core-needle biopsy was used as a
screening process following a suspicious finding on a mammogram,
the number of women without cancer who were subjected to surgical
biopsies dropped significantly. In this study, 1103 women underwent
surgical breast biopsy because either the core-needle biopsy
results were inconclusive or because the patient and/or surgeon
indicated a preference for the open procedure. Of this group, 42%
were found to have cancer, compared with only 19% of 1160 women who
underwent the surgical procedure 10 years ago, prior to the
introduction of the core-needle procedure.
Jessica Leung, MD, of Harvard Medical School, the lead
investigator, noted that in addition to the obvious benefit of
avoiding surgery in healthy women, the core-needle technique is
able to provide the patient with a diagnosis using a 30-minute
procedure that involves only a local anesthetic, has almost no risk
of infection, avoids disfigurement and scarring of the breast, and
allows the patient to return to normal activities immediately.
2
Furthermore, in the approximately 20% of cases in which the
findings are positive for cancer, the patient can proceed to
treatment quickly without concern for breast disfigurement that may
occur with the open procedure.
Leung concluded that, when appropriate, women should be given
the option of a core-needle biopsy. She noted, however, "there are
some circumstances in which surgical biopsies are indicated."
2
Such circumstances include lesions that are located deep within a
small breast or close to the chest wall, both of which make
accurate results difficult with the core-needle technique.
The Mammotest System
The Mammotest Plus/S System from Fischer Imaging Corporation
(Denver, CO) is a prone stereotactic breast biopsy system, offering
a procedure that can be accomplished in approximately 30 to 45
minutes (Figure 1).
Using the three-dimensional (3D) X-ray spatial location
technology, the DICOM-compliant system automatically calculates the
proper angles and directs the AutoGuide needle placement mechanism
with a stated accuracy of 1 mm. This needle mechanism provides
horizontal, vertical, and depth control. Rotational tube movement
allows 360š access to the breast.
The imaging component is a fiber optically coupled, charge
coupled device (CCD) with an element matrix of 1024 * 1024
pixilation, with each pixel at 50 µ per side, providing an overall
image area of 50 * 50 mm. With a 12-bit analog-to-digital
converter, the system has 4096 shades of gray and can display
images within 4 seconds of acquisition.
Recently, Fischer also introduced the MammoSound. This new
ultrasound guidance device provides practitioners with the option
of tracking the biopsy needle with real-time ultrasound guidance,
traditional stereotactic imaging, or a combination of both,
providing greater confidence in tumor identification.
"The Mammotest Plus/S System is a perfect amalgamation of the
lowest possible radiation, superior quality imaging, and swift and
accurate diagnoses," said Gerald Knudson, CEO of Fischer Imaging.
"We're proud to offer this fast, filmless image display biopsy
procedure."
The Mammotome Biopsy System
Since its clinical introduction in 1996, more than 750,000 women
have undergone breast biopsy using the Mammotome Biopsy System from
Ethicon Endo-Surgery (Cincinnati, OH). This vacuum-assisted biopsy
device (Figure 2) is suitable for sampling microcalcifications,
spiculated masses, asymmetric densities, and multifocal disease, as
well as diffuse tissue.
With the Mammotome system, the dual-lumen probe is positioned in
the breast using either prone or upright stereotactic or ultrasound
guidance. The center of the aperture is aligned with the center of
the lesion. Tissue is then suctioned into the aperture with the
SMART VAC computer-controlled vacuum system. The high-speed
rotating cutter advances forward until the specimen is captured.
The specimen is transported to a tissue collection chamber with the
assistance of the vacuum device, while the outer probe remains in
the breast. Rotation ceases when the cutter reaches its full
forward position and the cutter is withdrawn. Once all the
necessary specimens have been collected, a MicroMark Tissue Marker
can be inserted to aid in follow-up examinations. The entire
procedure is completed through a 0.25-inch incision in the
skin.
The vacuum-assisted device is able to remove multiple samples
and relatively large amounts of material with a single needle
insertion. In fact, in many cases, the probe can remove an entire
lesion if it is ¾ 1.5 cm.
A study presented at the 2001 meeting of the Radiological
Society of North America looked at the effectiveness of the
Mammotome Hand Held Vacuum-Assisted Biopsy System as a treatment
method for breast fibroadenomas.
3
As part of the year-long study, 30 women, aged 19 to 52 years,
underwent ultrasound-guided vacuum-assisted biopsy (UGVAB) for a
total of 34 suspected fibroadenomas. The imaging modality used for
patients aged >= 30 years was ultrasound and mammography. For
those under 30, ultrasound was used alone. The actual procedure was
performed in an ambulatory setting under ultrasound guidance for
all patients.
Tissue diagnosis confirmed that all 34 lesions were
fibroadenomas. Complete excision was accomplished in all 20 of the
lesions that were <1.5 cm. None of the 3 lesions >2 cm were
removed completely. Of the remaining 11 lesions, measuring 1.5 cm
to 2 cm, 8 were removed completely and 3 were only partially
removed. No evidence of recurrence was seen in any of the patients
during the 1-year follow-up period. Only 1 of the 6 patients with
incompletely excised lesions opted for surgical excision; the
remaining patients chose conservative follow-up.
Based on these findings, the researchers suggest that UGVAB may
provide an option of definitive treatment for breast fibroadenomas,
especially for lesions <1.5 cm.