Evaluation of a breast irregularity may lead to your doctor recommending a breast biopsy. This may arise because of a lump that was detected on examination of the breast or a finding seen on a mammogram or breast ultrasound. A breast biopsy is usually performed to determine if the abnormality is cancerous. A biopsy involves getting a tissue specimen that can be examined under a microscope to look for cancer cells.
There are several different techniques used to obtain the actual sample. The specific type of biopsy depends upon the size of the lump, whether the lump can be felt by the doctor's fingers, and what tests need to be performed on the tissue sample.
A doctor can do fine-needle aspiration (also called a FNA) in the office by inserting a very slender needle into the area of concern and drawing out (aspirating) either fluid from a cyst or a small amount of tissue from a solid mass. Although this procedure is sometimes called a FNA biopsy, it is different from other breast biopsies. It is intended to draw out a core of tissue from a suspicious area in the breast. Tissue from a mass, and sometimes fluid from a cyst, is then sent for microscopic evaluation to determine whether cancer is present.
Aspirating a cyst: Not all cysts need to be drained. If the cyst is a simple cyst (one that looks clear under ultrasound) and isn't causing discomfort, it usually doesn't require aspiration.
Fine-needle aspiration is commonly used to drain a tender cyst or a complex cyst. The tender cyst is drained to confirm that it is a simple cyst and also to relieve pain. A complex cyst is one that appears on ultrasound to contain cellular materials or tissue within the fluid. In rare cases, the cellular material could represent cancerous cells.
Sometimes fluid from the cyst will be bloody. When that happens, the doctor will send the fluid to be analyzed in the laboratory to determine whether the material contains cancerous cells.
Even the cells that are removed during aspiration are noncancerous; the doctor may still recommend further testing if there is any concern that there is a cancer. This may occur if the cytopathologist (the specialist who examines the cells under a microscope) cannot make an unequivocal diagnosis of cancer, but does notice some irregularities in the appearance of the cells.
Aspirating a solid mass: With fine-needle aspiration of a solid mass, the doctor uses a slightly different technique. The doctor inserts the slender needle through the skin into the mass. Suction is applied to pull cells out of the mass. The cells are spread on a slide that is sent to the pathology laboratory. Or, the doctor may decide to use a needle that can remove a core of the solid mass to obtain more material for examination under the microscope.
If the cells are definitely cancerous, the patient and doctor can proceed with plans for treatment. However, if the cells appear benign, the patient will still need further diagnostic evaluation with either a large-core needle biopsy or open surgical biopsy.
Large-Core Needle Biopsy
This method involves the use of a hollow needle to remove samples of breast tissue to be examined microscopically. Since the early 1990s, large-core needle biopsy has been the diagnostic method of choice to evaluate abnormalities that are visible on a mammogram but cannot easily be felt by hand. In the more advanced medical centers, it is considered the standard of care.
Large-core needle biopsy can be performed using either mammographic (stereotactic) or ultrasound guidance. Mammographic calcifications are usually biopsied using the stereotactic method, whereas mammographic densities can be sampled by ultrasound guidance when the density is visible by ultrasound and by stereotactic guidance when the density is visible only by mammography.
To perform a large-core needle biopsy, the doctor anesthetizes the skin and inserts a needle the thickness of a pen tip into the breast. Using the mammogram or ultrasound images, or by feeling the lump, the doctor guides the needle into the area of concern and removes a tissue sample through the needle with the help of a vacuum. Core needle biopsy may cause some bruising but leaves only a tiny dot for a scar.
Core needle biopsy may not be suitable for patients who have an irregularity close to the chest wall, the nipple, or the surface of the breast; those with calcifications that require magnification; or women with very small breasts. In these circumstances, fine-needle aspiration may be the preferred choice. Also, if a patient is anticoagulated (taking blood thinners), the physician will take measures to minimize the possibility of bleeding following the procedure. In some of these situations, accurate results may not be possible and an open surgical biopsy will be recommended.
Stereotactic core needle biopsy: With this procedure, the mammographer or surgeon looks at a mammogram image while performing the biopsy in order to precisely locate the suspicious area. This method is useful when the doctor can see an abnormality on a mammogram but cannot feel it in a breast exam.
The patient lies face down on a specially designed table with the breast compressed. The doctor injects a local anesthetic, makes a 3-mm skin incision, and then inserts the core biopsy needle. Usually results are available within a day or two. Women who cannot remain still for 20 to 40 minutes because of physical illness or other problems are not good candidates for stereotactic core needle biopsy.
Ultrasound-guided core needle biopsy: With this method, the radiologist uses ultrasound imaging to precisely confirm the location for biopsy with the core needle. The doctor makes only a single puncture in the skin to extract three to six separate core needle tissue samples for analysis. The patient may feel some pressure but no pain.
The procedure takes only a few minutes. Following the procedure, a bag of ice is placed on the site for 15 to 30 minutes, and most patients are able to resume normal activity almost immediately afterward. As indicated above, if the patient is taking blood thinners, modifications of the blood-thinning medicines should be considered.
Results of core needle biopsy: In experienced centers, 65% of women who undergo this procedure have a benign diagnosis and can resume having annual mammograms. Another 25% of patients have a malignancy and proceed with treatment.
For the remaining 10% of patients, results are inconclusive. For these patients, the next step is often a type of biopsy known as an excisional biopsy.
If the core biopsy suggests atypical ductal hyperplasia, surgical biopsy can help determine if the abnormality is atypical hyperplasia (about 81%), DCIS (ductal carcinoma in situ at 13%), or an invasive breast cancer (in only 6%). If, on the other hand, the core biopsy demonstrates tissue changes known as atypical lobular hyperplasia, then excisional biopsy may not be necessary.
If lobular carcinoma in situ is found, several treatment options may be considered, such as:
- Continued close follow-up
- Long-term treatment with an estrogen blocker (for example, tamoxifen)
- Bilateral mastectomies (rarely)
For patients whose core needle biopsy shows DCIS, the full lesion will need to be removed for further examination in the laboratory. For these patients, the likelihood of an invasive breast cancer ranges from 0% to 28%.
There are two additional considerations when using a large-core needle biopsy. If the lesion is large, the breast surgeon may want to mark the area of biopsy with a clip that can be detected by mammography, especially if a subsequent larger biopsy is planned. It will also mark the area of the cancer and allow easier identification of the area if the patient undergoes additional treatments and if an assessment of response is desired.
If the lesion is small, the clip will serve to mark the anatomic location of the breast abnormality, which on occasion can be removed entirely by the biopsy. Having this information will be useful if other treatments are considered, such as radiation.
Patients may ask whether the "needle tract" that is created by the needle biopsy can be "seeded" with cancer cells (thus potentially spreading the cancer cells along the needle tract), as the needle is withdrawn after the biopsy has been obtained. This is hypothetically possible and can be minimized by considering radiation treatment in those women who are not going to undergo a mastectomy and by selecting the shortest distance from the skin to the lesion.
For a surgical biopsy, the surgeon makes an incision in the skin and removes all or part of the abnormal tissue for examination under a microscope. An excisional biopsy is the removal of the entire area of concern, along with a narrow margin of healthy tissue all the way around it. This is done when the abnormal area is small.
An incisional biopsy is the removal of a portion of the abnormality and is appropriate for larger lesions in order to secure a diagnosis while minimizing the effect on the breast's appearance.
Surgical biopsy can be performed under local anesthesia, intravenous sedation, or general anesthesia, depending on the doctor's recommendation and your preference. The procedure takes about an hour, and the recovery period is less than two hours.
When a breast mass or an area of calcifications cannot be felt, the surgeon may choose to use a procedure called wire localization to help identify the tissue for later surgical removal. After applying a local anesthetic, the mammographer inserts a hollow needle into the breast and, guided by ultrasound or mammography, locates the suspicious area. The mammographer inserts a thin wire with a hook on the end through the hollow needle and into the breast alongside the lesion. The mammographer then removes the needle, leaving the wire in place to serve as a guide to help the surgeon find the area of breast tissue to be excised later.
When a core needle biopsy is inconclusive, which occurs 10% of the time, a surgical biopsy provides a firm diagnosis. In addition, if a complex cyst does not completely collapse during aspiration, doctors may perform surgical biopsy to find out whether there is a cancer within the cyst.
Unlike needle biopsies, a surgical biopsy leaves a visible scar on the breast and sometimes causes a noticeable change in the breast's shape. It's a good idea to discuss the placement and length of the incision with your surgeon beforehand. Also ask your surgeon about scarring and the possibility of changes to your breast shape and size after healing.
In the case of a wire localization surgical biopsy, there is a 2% chance the surgeon will miss the site in question. Of the 20% of women who are diagnosed with cancer following an open surgical biopsy, most require a second breast surgery to make sure all the cancer tissue has been removed along with a safe margin of healthy tissue.
Women who have been diagnosed with ductal carcinoma in situ (DCIS) generally will need a more extensive surgical biopsy procedure to ascertain that all of the abnormal breast tissue has been removed and the calcifications identified have been removed. The specimen may also be marked with ink to show the orientation of the excised (surgically removed) tissue. This helps the pathologist determine whether any residual cancer was present at the cut surface (surgical margin) of the tissue. If cancer cells are present at the cut surface, additional excision may be required.
There may also be circumstances when the surgically removed specimen obtained from surgical biopsy is further evaluated with a mammogram, to determine the adequacy and accuracy of the removed tissue. The calcifications that may have been identified on the mammogram can be examined and correlated in the removed specimen.
Also some patients may need another mammogram several weeks to months after the surgical removal of the abnormality. This is done to be certain that the calcifications were removed entirely and the mammographic irregularity leading to the surgical biopsy is no longer present. If these criteria are not satisfied, an additional surgical excision may need to be performed.
As with all procedures that obtain breast tissue for diagnostic evaluation, if the mammographic abnormality was considered to be a high-risk BIRADS 4 or 5, some surgeons may consider an evaluation of the lymph nodes under the armpit and, if any abnormalities are detected, consider a biopsy, using fine-needle aspiration or other technique, of the lymph nodes under this area.
If cancer cells are identified, the following information may also be included in the report:
Size – The size of the lump is measured in centimeters or millimeters.
Spread – This is a measure of whether the cancer is invasive (meaning it has invaded the surrounding tissue) or in situ (meaning cancer cells are present, but are localized). If there is evidence that the cancer cells are invading blood vessels or the lymphatic system, this is an unfavorable prognostic factor. Noninvasive breast cancer is called DCIS (ductal carcinoma in situ) or LCIS (lobular carcinoma in situ). Another key finding is whether the margins of the specimen are involved with cancer. If the margins are involved, or if the margins are too thin, it suggests that there is tumor remaining in the patient. This finding may provoke a repeat surgery or affect radiation planning.
Cell type – The most common types of cancer cells are ductal and lobular.
Estrogen- and progesterone-receptor status — Cells that have the estrogen receptor are called estrogen-receptor positive, and cells that have the progesterone receptor are called progesterone-receptor positive. These receptors are like tiny locks on the cells. They can be "unlocked" or stimulated to grow by the presence of these hormones. These tumors are less likely to grow if these hormones are not present. In general, estrogen-receptor-positive breast cancer is less aggressive than estrogen-receptor-negative breast cancer. The presence or absence of progesterone receptors also is important in evaluating the cancer, but not as important as the estrogen receptor.
Nuclear grade – This is an evaluation of how fast the nuclei of cancer cells can divide and how normally the cells are arranged in relation to each other. The nuclear grade is on a scale of one to three. The higher the score, the more aggressive the cancer.
HER-2/neu testing – Human epidermal growth factor receptor 2 (HER-2) is a gene that directs cells to produce a protein with the same name. This protein helps regulate how quickly cells grow and divide. When breast cancer cells have an overabundance of HER-2 genes, then too much of the protein may be produced. Twenty percent to 30 percent of breast cancers show an overabundance of HER-2. These tumors tend to be aggressive and less responsive to standard chemotherapy.
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