If a woman or her doctor detects a suspicious breast lump, or if X-rays find an abnormal area, the physician (surgeon or radiologist) must take a biopsy (tissue sample), to be examined under a microscope. This biopsy reveals whether a cancer is present. Each type of biopsy has advantages and disadvantages; choosing one depends on each patient's situation.
The fine needle aspiration biopsy (FNAB) uses a thin needle, smaller than the needle used for blood tests. It uses a smaller needle than the core biopsy, but is also less accurate. While the doctor touches the lump, he or she guides the needle in by hand. If the lump can't be felt easily, the doctor might use ultrasound to guide the needle. High-frequency sound waves produce images of breast tissue; the doctor can watch the needle on a screen as it moves toward and into the mass.
Another technique, stereotactic core needle biopsy, uses computers guided by mammograms taken from two angles to map the exact location of the mass. Then the computer guides the needle to the right spot so the physician can take a sample of the tissue.
If the lump is solid, the physician removes small tissue fragments with a hollow needle. This is called a core needle biopsy. It removes a small cylinder of tissue (about 1/16-inch in diameter and 1/2-inch long) from a breast abnormality. This technique requires a needle that is larger than the one used in FNAB. As with FNAB, a core needle biopsy can sample abnormalities felt by the doctor as well as smaller ones pinpointed by ultrasound or stereotactic methods.
In some cases a surgical biopsy may be needed to remove all or part of the lump for microscopic examination.
To remove an entire lesion (a lump or any other tissue abnormality) doctors perform an excisional biopsy, taking out the lump. During an excisional biopsy, the surgeon may use a procedure called wire localization if there is a small lump that is hard to locate by touch, or if certain areas look suspicious on an x-ray. After numbing the area with a local anesthetic, a hollow needle is placed into the breast and x-ray pictures are taken to guide the needle to the abnormal spot. The surgeon or radiologist inserts a thin wire through the center of the needle. The hollow needle is then removed, and the surgeon uses the wire as a guide during the excision procedure.
An incisional biopsy is a type of surgical biopsy that removes only part of a mass. Unlike a needle biopsy, which also removes a sample of a mass, in an incisional biopsy the doctor uses a scalpel to make an incision in the skin and cut away a piece of the abnormality. Incisional biopsy is usually used only in cases of very large lumps.
Local anesthesia is generally used for fine needle and core needle biopsies. For incisional and excisional biopsies, sedation is often used in addition to a local anesthetic. General anesthesia is rarely used for breast biopsies.
A sentinel node biopsy is a technique not for determining the presence of breast cancer, but for identifying its spread, if any, into the lymph nodes in the armpit. By examining the "sentinel node," surgeons can predict with greater than 98% accuracy the presence of cancer cells in the other lymph nodes.