Biopsy

A radiologic study (mammogram, ultrasound, etc.) is not enough to establish an initial diagnosis of cancer. A diagnosis of cancer must be proven by the presence of cancer cells as seen under a microscope. This is why a biopsy—a very small operation that removes tissue from an area of concern in the body—is required to get the cells for microscopic analysis.

A biopsy helps doctors zero in on the size, type, and kind of breast cancer you may have. Biopsies are performed on any kind of abnormality that your doctor can feel or that looks suspicious. It's usually a very simple procedure. In the United States, only about 20% of women who have biopsies turn out to have cancer. By contrast, in Sweden, where cost accounting is much stricter and only the most suspect lesions are biopsied, 80% of biopsies turn out to be cancerous (malignant).

Biopsy techniques

Various techniques are used to biopsy tissue, and it's likely that your surgeon will try to use the least invasive procedure possible. Tissue removed by the various types of biopsies described below is examined with a microscope for cancer cells. For more about this process, see Understanding Your Big Picture.

• Needle biopsy of palpable lesions is least invasive. It can be done in the doctor's office. The surgeon obtains material for microscopic analysis using a needle with a hollow center. Results are often available in 24 hours. New technologies are helping to improve the effectiveness of needle biopsy. In some cases, a technique called needle localization guides biopsy of a non-palpable lesion (a mass that can't be felt) that was detected by mammography.
  
  A long, thin hollow needle is placed in the lesion with the help of mammography or ultrasound to see where the needle is going. Cells are extracted through the center of the needle. A collapsible hook at the end of the needle keeps the needle in place until the surgery is done. X-rays verify that the abnormal area seen on the original X-rays is the same area into which the surgeon inserts the needle. This biopsy technique has the highest risk of "false negatives," which is when the biopsy result says normal, even though a cancer is present. The reason for this is probably that the needle doesn't always pick up the cancer cells.
• Stereotactic needle biopsy (core biopsy) removes multiple pieces of a lesion. If the lesion can't be felt, the needle is guided to the area of concern with the help of mammography or ultrasound. If a cancer is only found by MRI, then needle biopsy may be guided by that technique. A small metal clip may be inserted into the breast to mark the site of biopsy in case the biopsy proves cancerous and additional surgery is required.
• Incisional biopsy is more like regular surgery—it involves removing a small piece of tissue for sectioning and examination. Often, incisional biopsies are done when needle biopsies are inconclusive or if the lump, mammographic change, or suspicious rash is too extensive or too big to be removed easily. There is the possibility that you will have false negatives with both needle biopsy and incisional biopsy. But the advantage to each is the quick results.
• Excisional biopsy is the most involved kind of biopsy. It attempts to remove the entire suspicious lump of tissue from the breast. This is the surest way to establish the diagnosis without winding up with a false negative. Removing the entire lump also provides you some peace of mind. Both incisional and excisional biopsies can be done in an outpatient center or hospital, using local anesthesia.

Before your biopsy

Biopsies are not medical emergencies and can be scheduled at your convenience. But for peace of mind, most women want their biopsies done "yesterday." Before proceeding with a biopsy, your doctor should review the mammogram with you, show you the area in question, discuss how and why the biopsy will be performed, answer any of your questions, and arrange for you to sign required consent forms.