Core Needle Biopsy for Your Breast

Young woman wearing scrubs and surgical gloves, preparing syringe

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A core needle biopsy (CNB) is used when your doctor needs more information about a breast lump than a mammogram, ultrasound, or fine needle aspiration can give.

A core needle, or hollow core needle, can be used to get small tissue samples from a breast lump. The tissue samples will be sent to the pathology lab for examination. This procedure can be done in an office, clinic or hospital by a doctor who is trained in the technique. Having a core needle biopsy might help you avoid an open surgical biopsy.

Other names for a CNB:

  • hollow core needle biopsy
  • incisional needle biopsy

Reasons to Have a CNB

Having a breast biopsy of any kind can be stressful, but it's a good way to find out the true nature of a breast mass that is causing concern. You may have already had a fine needle aspiration (to remove fluid or tissue), but didn't get clear results. A hollow core needle (16-, 14-, or 11-gauge needle) can take larger tissue samples of a breast mass as well as nearby healthy breast tissue. Your pathologist can do more accurate tests and microscopic examinations on larger tissue samples, giving you and your doctor a better idea of how to proceed.

Types of Techniques

Core needle biopsies are done several different ways, depending on the size or location of the breast mass being sampled. Freehand needle biopsy can be used for lumps or masses that can easily be felt. But if a lump is too small to be felt, or too deep to aim a needle at, there are other methods that use imaging and mechanical assistance: ultrasound-guided needle biopsy, stereotactic needle biopsy, and vacuum-assisted biopsy.

What to Expect

You will be awake during the procedure, but your breast will be numbed with a local anesthetic. Your doctor will locate the lump by touch or with guidance from imaging technology. Your doctor will insert the core needle through your skin into the lump to take tissue samples. To ensure the accuracy of results, three to six samples will be taken. You should expect to feel some pressure during the procedure, but be sure to let your doctor know if you feel significant pain. After the procedure, you may have some bruising at the needle sites, but no scars. You will be able to return to work or home right away.


Your tissue samples will be tested in the pathology lab, and a written report will be sent to your doctor. A negative result means that no cancer was found. A positive result means that the mass is malignant, and more tests will be needed to get an accurate diagnosis.

Test Accuracy

Because a core needle can remove a larger tissue sample, and more samples are taken for comparison, a core needle biopsy is more accurate than a fine needle aspiration. A core needle biopsy may be between 97 and 100% accurate in giving a diagnosis. If you have very small breasts or very hard lumps, a core needle may not be able to take a good tissue sample, and other biopsy methods may be required.

Benefits and Risks

A core needle biopsy is more accurate than an aspiration and less invasive than an open surgical or excisional biopsy. The needle biopsy will leave no external or internal scars, and so it will not affect future breast imaging studies. There is always the chance that the needle may miss a malignant area, but your doctor will try to minimize this possibility. A core needle biopsy is not a treatment, and it will not remove all of a malignancy. If your results come back positive for cancer, you will need to consider more tests and treatment.

View Article Sources
  • Sources:
    American Cancer Society. For Women Facing a Breast Biopsy. Core Needle Biopsy (CNB). Revised: 09/19/2007.
  • International Journal of Cancer. Diagnostic accuracy of stereotactic large-core needle biopsy for nonpalpable breast disease: Results of a multicenter prospective study with 95% surgical confirmation. Helena M. Verkooijen. Vol. 99, No. 6, Pages 853-859, 2002.
  • National Cancer Institute. Understanding Breast Changes: A Health Guide for Women. Follow-Up Tests to Tell You More: Core Needle Biopsy.