Imaging studies such as mammogram and MRI, often along with physical exams of the breast, can lead doctors to suspect that a person has breast cancer. However, the only way to know for sure is to take a sample of tissue from the suspicious area and examine it under a microscope.

A biopsy is a small operation done to remove tissue from an area of concern in the body. If your doctor feels anything suspicious in your breast, or sees something suspicious on an imaging study, he or she will order a biopsy. The tissue sample is examined by a pathologist (a doctor who specializes in diagnosing disease) to see whether or not cancer cells are present. If cancer is present, the pathologist can then look at the cancer’s characteristics. The biopsy will result in a report that lays out all of the pathologist’s findings.

Biopsy is usually a 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 suspicious lesions are biopsied, 80% of biopsies turn out to be cancerous (malignant).

Different techniques can be used to perform biopsy, and it’s likely that your surgeon will try to use the least invasive procedure possible — the one that involves the smallest incision and the least amount of scarring. However, the choice of procedure really depends on your individual situation. Biopsy can be done by placing a needle through the skin into the breast to remove the tissue sample. Or, it can involve a minor surgical procedure, in which the surgeon cuts through the skin to remove some or all of the suspicious tissue.

Fine needle aspiration (FNA) is the least invasive method of biopsy and it usually leaves no scar. You will be lying down for this procedure. First, an injection of local anesthesia is given to numb the breast. The surgeon or radiologist uses a thin needle with a hollow center to remove a sample of cells from the suspicious area. In most cases, he or she can feel the lump and guide the needle to the right place.

In cases where the lump cannot be felt, the surgeon or radiologist may need to use imaging studies to guide the needle to the right location. This is called ultrasound-guided biopsy when ultrasound is used, or stereotactic needle biopsy when mammogram is used. With ultrasound-guided biopsy, the doctor will watch the needle on the ultrasound monitor to guide it to the area of concern. With stereotactic mammography, mammograms are taken from different angles to pinpoint the location of the breast mass. The doctor then inserts the hollow needle to remove the cell sample.

Core needle biopsy uses a larger hollow needle than fine needle aspiration does. If you have this type of biopsy, you’ll be lying down. After numbing the breast with local anesthesia, the surgeon or radiologist uses the hollow needle to remove several cylinder-shaped samples of tissue from the suspicious area. In most cases, the needle is inserted about 3 to 6 times so that the doctor can get enough samples. Usually core needle biopsy does not leave a scar.

If the lesion cannot be felt through the skin, the surgeon or radiologist can use an image-guided technique such as ultrasound-guided biopsy or stereotactic needle biopsy. A small metal clip may be inserted into the breast to mark the site of biopsy in case the tissue proves to be cancerous and additional surgery is required. This clip is left inside the breast and is not harmful to the body. If the biopsy leads to more surgery, the clip will be removed at that time.

In addition to offering quick results without significant discomfort and scarring, both fine needle aspiration and core needle biopsy give you the opportunity to discuss treatment options with your doctor before having any surgery. In some cases, needle biopsy can be performed right in the doctor’s office, unless your doctor needs the help of imaging equipment to guide the biopsy. However, needle biopsy has a higher risk of a “false negative” result — a result suggesting that cancer is not present when it really is. This is likely because needle biopsy removes a smaller amount of tissue than surgical biopsy does and may not pick up the cancer cells. Your doctor may recommend a surgical biopsy in follow up to, or instead of, a needle biopsy. Together you can decide what is best for your situation.

Vacuum-assisted breast biopsy, also known by the brand names Mammotome or MIBB (which stands for Minimally Invasive Breast Biopsy), is a newer way of performing breast biopsy. Unlike core needle biopsy, which involves several insertions of a needle through the skin, vacuum-assisted biopsy uses a special probe that only has to be inserted once. The procedure also is able to remove more tissue than core needle biopsy does.

For vacuum-assisted breast biopsy, you’ll lie face down on an exam table with special round openings in it, where you place your breasts. First, an injection of local anesthesia is given to numb the breast. Guided by mammography (stereotactic-guided biopsy) or ultrasound, the surgeon or radiologist places the probe into the suspicious area of the breast. A vacuum then draws the tissue into the probe. A rotating cutting device removes a tissue sample and then carries it through the probe into a collection area. The surgeon or radiologist can then rotate the probe to take another sample from the suspicious lesion. This can be repeated 8 to 10 times so that the entire area of concern is thoroughly sampled.

In some cases, a small metal clip is placed into the biopsy site to mark the location, in case a future biopsy is needed. This clip is left inside the breast and causes no pain or harm. If the biopsy leads to more surgery, the clip will be removed at that time.

Vacuum-assisted biopsy is becoming more common, but it is still a relatively new procedure. If you are having this form of biopsy, make sure that the surgeon or radiologist is experienced at using the equipment.

Incisional biopsy is more like regular surgery. After using local anesthesia to numb the breast and giving you an injection to make you drowsy, the surgeon uses a scalpel to cut through the skin to remove a piece of the tissue for examination.

As with needle biopsy, if the surgeon cannot feel the lump or suspicious area, he or she may need to use mammography or ultrasound to find the right spot. Your surgeon also may use a procedure called needle wire localization. Guided by either mammography or ultrasound, the surgeon inserts a small hollow needle through the breast skin into the abnormal area. A small wire is placed through the needle and into the area of concern. Then the needle is removed. The doctor can use the wire as a guide in finding the right spot for biopsy.

Your doctor may recommend incisional biopsy if a needle biopsy is inconclusive — that is, the results are unclear or not definite — or if the suspicious area is too large to sample easily with a needle. As with needle biopsy, there is some possibility that incisional biopsy can return a false negative result. However, you do get the results fairly quickly. Given that it is a surgical procedure, incisional biopsy is more invasive than needle biopsy, it leaves a scar, and it may require more time to recover.

Excisional biopsy, the most involved form of biopsy, is surgery to remove the entire area of suspicious tissue from the breast. In addition to removing the suspected cancer, the surgeon generally will remove a small rim of normal tissue around it as well, called a margin.

As with incisional biopsy, if the surgeon cannot feel the lump or suspicious area, he or she may need to use mammography or ultrasound to find the right spot. Your surgeon also may use needle wire localization to mark the right area for biopsy.

Excisional biopsy is the surest way to establish a definite diagnosis without getting a false negative result. Also, having the entire lump removed may provide you with some peace of mind. However, excisional biopsy is more like regular surgery, and it will leave a scar and require more time to recover. Like incisional biopsy, excisional biopsy is performed with local anesthesia.

Biopsies are not medical emergencies and can be scheduled at your convenience. But for peace of mind, most people want their biopsies done "yesterday."

Medical guidelines say that about 90% of biopsies should be needle biopsies, the least invasive procedure. Still, research has shown that about 70% of breast biopsies are surgical biopsies. This means that many women who don't have cancer are having unnecessary surgery. It also means that women who are diagnosed with breast cancer have to have a second operation to remove the cancer.

Before proceeding with a biopsy, be sure to ask your doctor to:

review the results of your mammogram and any other imaging studies with you

show you the area in question

explain the type of biopsy that's recommended for you and explain why that type of biopsy is recommended; if surgical biopsy is recommended ask if needle biopsy can be done

discuss how and why the biopsy will be performed

answer any of your questions

arrange for you to sign required consent forms

tell you when and how you can get the biopsy results

A few days to a week after biopsy, your doctor should give you a pathology report that explains what was found in the tissue sample. See Understanding Your Pathology Report  for more information.

— Last updated on July 27, 2022, 1:48 PM

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