Stereotactic Breast Biopsy

Radiologic Technology, May, 2001 by Teresa G. Norris

When a woman is informed about a mass in her breast, anxiety and concern over possible malignancy naturally follow. A rapid, accurate and minimally invasive diagnostic technique can help ease some of that anxiety. Stereotactic breast biopsy, a relatively new procedure, offers quick assessment of breast lesions and provides an alternative to surgical biopsy for many indications.

First introduced in Switzerland in 1976, stereotactic procedures use mammography and stereotactic principles to biopsy breast lesions with needles. The first dedicated, prone stereotactic table was introduced at the University of Chicago in the mid 1980s, and in 1989 Parker reported on stereotactic biopsies using an automated biopsy gun and a large-gauge needle. Accuracy rates increased dramatically with this approach.[1] In late 1992, the time required to process images decreased with development of digital spot mammography for stereotactic guidance, making biopsies faster and more accurate.

One hurdle to the growth of stereotactic breast biopsy, at least early on, was lack of acceptance by surgeons. Because the technique shifted greater responsibility to radiologists, some surgeons felt threatened. However, from a patient's point of view, competent, uninterrupted care is more important than who provides the care.[2]

Today, stereotactic core-needle biopsies have become an accepted method for biopsy of nonpalpable lesions, with a reported sensitivity ranging from 79% to 100%. In addition to saving money (they are about 75% less expensive than surgical biopsies), stereotactic procedures have achieved a high level of patient and physician acceptance.[3]

Stereotactic Biopsy Vs Needle Localization

In traditional breast biopsy, radiography assisted solely in placement of a localization wire. The patient was transferred, with wire in place, to a surgical suite for open biopsy. With stereotactic biopsy, the entire procedure can be performed in the radiology department. (See Fig. 1.) In some cases, the procedure can take place immediately following mammography.[2]

[ILLUSTRATION OMITTED]

Many physicians argue that one-stage procedures, in which excisional biopsy is followed immediately by definitive surgery, such as mastectomy or lumpectomy, represent an advantage for open biopsy. However, one-stage procedures are uncommon, partly because of low rates of malignancy and partly because the physician normally consults with a patient about all treatment options prior to definitive surgery.

Studies have shown that as many as 9 out of 10 patients biopsied may have benign lesions. The documented miss rate for excisional biopsy, its substantial cost compared with percutaneous methods and the physical and psychological trauma associated with surgical procedures have increased favor for all percutaneous methods.[1]

Core Biopsy vs Fine-needle Aspiration

Physicians began replacing open biopsy with fine-needle aspiration biopsy of the breast to reduce the number of 2-stage surgical procedures (ie, open biopsy and a second, definitive surgical treatment.) In fine-needle aspiration biopsy, a 21- to 23-gauge needle with an attached syringe is passed through the suspicious area several times, and the extracted samples are placed on glass slides. Fine-needle aspiration yields cellular material suitable for cytologic evaluation only. Accurate evaluation of fine-needle samples requires a cytopathologist, a specialty not available in all facilities.[1]

Many surgeons did not like relying on fine-needle aspiration biopsy results because in many cases insufficient tissue was obtained. Samples acquired with this method also produced a high false-negative rate and occasional false-positive results. Often, the physician was unable to deliver a definitive benign diagnosis.[4] (See Table 1.)

Table 1
Comparison of Fine-needle Aspiration
And Core-needle Biopsy Techniques
For Nonpalpable Breast Lesions1

                         Fine-needle    Core Biopsy
                         Aspiration

Needle size (gauge)      20 to 22       11 to 14

Guidance techniques      Ultrasound,    Ultrasound,
                         stereotactic   stereotactic

Pathologic evaluation    Cytology       Histology
of sample

Rate of inadequate       0% to 37%      <1%
sample

Differentiates in situ   No             Yes
from invasive cancer?

Cost(*)                  $              $$

(*) The cost per procedure depends predominantly on the
choice of guidance technique. The cost of the needle is also
a contributing factor: 22-gauge hypodermic needles used for
fine-needle aspiration are relatively inexpensive; automated
biopsy guns use needles of variable gauges, ranging from 14
to 21, and are intermediate in price; the 11-gauge core biopsy
needles used with the vacuum-assisted biopsy probe are
most expensive at approximately $200 each.

Core biopsy uses a different needle than fine-needle aspiration biopsy. In core biopsy, a large cutting needle, most commonly 14 gauge, is advanced into the breast using an automated instrument to extract a core of tissue. Because more tissue is removed, insufficient sampling is rare. Tissue obtained from stereotactic core biopsy requires only histologic examination.