Breast cancer: needle biopsy

Needle biopsy is a simple procedure that allows a small amount of tissue to be removed from the breast so that it can be examined under a microscope by a pathologist. (A pathologist is a medical specialist who studies how changes in tissues relate to disease.) It is most often used to diagnose a "feelable" lump or abnormal tissue detected on a mammogram or ultrasound. In many cases, mammograms and ultrasound give enough information to diagnose breast cancer. If the diagnosis is uncertain, breast tissue samples will be taken either with a needle biopsy or surgery.

Tissue sampling: needle biopsy versus surgery

As the name "needle biopsy" suggests, tissue samples from the breast are obtained with needles rather than surgery. The advantage of needle biopsy over surgery is that it leaves little or no scarring, and is less costly. With surgery, scar tissue that forms inside the breast can temporarily interfere with the interpretation of subsequent mammograms (see Figure 1). With the surgical option, the entire lump is removed, often using local anesthesia. It is a simple procedure where the patient enters and leaves the hospital on the same day.

Three types of needle biopsy

• Fine-needle aspiration biopsy - a very narrow needle is used to draw a small tissue specimen. It is the cheapest and least invasive of the needle biopsy procedures and requires the pathologist to have specialized training in cytopathology.
• Large-core needle biopsy - multiple samples of tissue are removed with a wider needle.
• Directional vacuum-assisted needle biopsy device - removes core samples with a wider needle attached to a vacuum device that collects more tissue in a shorter period of time and requires usually a single needle insertion.

Which produces the best test results?

Compared to surgery, a needle biopsy obtains only a small portion of the abnormal tissue and can be less accurate. This error tends to decrease as the needle size increases. The accuracy of needle biopsy depends on the following:

• Accurate positioning of the needle - mammography or ultrasound pictures are used to accurately guide the insertion of the needle into a lump. For large lumps that can be felt, needle biopsy can be performed without imaging guidance. The lump is simply held still between the fingers while the needle is positioned.
• Adequate sample size - the size of the sample(s) obtained must be adequate (large enough for the pathologist to examine). Again, the bigger the needle, the larger the sample.
• Skilled interpretation of results - the pathologist must be an expert in examining the specimen, especially with fine-needle aspiration therapy.

How is the type of needle biopsy selected?

The type of needle biopsy performed will depend on:

• The type of breast abnormality being assessed - usually the radiologist decides which needle biopsy test is most suitable.
• The skills of the individuals involved - for example, some institutions don't have a cytopathologist on staff, which eliminates the fine-needle aspiration option.
• Equipment available - the directional vacuum-assisted needle procedure can be done only with certain models of mammography machines and special equipment that is not universally available.
• The necessity for accuracy - larger needles provide more specific information - for both cancerous and noncancerous lumps. This can be particularly important in planning treatment for cancerous lumps - and can result in fewer surgeries being required for many women with cancer.

As well, the larger the needle the greater the cost, with the directional vacuum-assisted needle biopsy device being the most expensive, and fine-needle assisted biopsy the least expensive. Also, larger needles can leave small marks. Both the large-core needle biopsy and the directional vacuum-assisted needle biopsy require an initial puncture in the skin made with a scalpel blade.

It is important to discuss your options with a genetic counsellor before having genetic testing done so that you are informed of all of the benefits and consequences of the test. It may also be a good idea to talk to other women who have had genetic testing done to see how it has affected their lives.

If you test positive for one of the breast cancer genes, there are several options for decreasing your chances of developing breast cancer, if you should choose to do so, including closer screening, surgery, hormonal therapy, or lifestyle changes.