Mammographic Needle Localization Biopsies
Todd Doyle, MD
Last Modified: June 18, 2009
Dear OncoLink "Ask the Experts,"
In my last mammogram they found 9 microcalcifications in a cluster in my left breast, which was an increase over past mammograms.
It was suggested to my husband and me that I have a biopsy procedure done. They explained that I would go for another mammogram, and the radiologist would insert a needle, then a wire of sorts to pin point the location for the surgeon. She would then make a small incision and then somehow remove an area slightly larger than the area of the cluster of calcifications.
Is this sufficient or should I be having a surgical procedure?
Todd Doyle, MD, OncoLink Editorial Assistant, responds:
Thank you very much for your interest and question regarding the significance of microcalcifications on mammography and needle localization biopsy for diagnosis.
Screening mammography has been shown to reduce mortality rates from breast cancer by 20 to 30%. This provides compelling evidence that early detection and treatment can prevent the progression of disease to metastasis (spread of cancer) and eventually death.
Findings which are considered suspicious for malignancy on a mammogram include: a mass with ill-defined (or spiculated) margins, distortion of the normal pattern of breast tissue (architectural distortion), skin or nipple changes, and "microcalcifications". Calcifications are worrisome for breast cancer when they are less than 0.5mm in size and are clustered with a variety of sizes and shapes. Using guidelines currently accepted in the U.S., the probability that a suspicious non-palpable (meaning that you cannot feel it, but is found on mammogram) lesion found on screening mammography is cancerous is 20 to 30%. Given this low percentage of cancers, there will be a fair number of negative biopsies. However, doing fewer biopsies (and just watching borderline suspicious lesions) would reduce the number of negative biopsies, but this would be at the cost of reducing the sensitivity of the test (not diagnosing a number of women with cancer at the earliest stages). Obviously each woman's risk of having a positive biopsy is different and is based on many factors, including age, family history, clinical findings, and number and type of abnormalities found on the mammogram.
There are several techniques that can be used to help the surgeon (or radiologist in some cases) find the area to biopsy when it cannot be palpated, but mammographic needle localization biopsy is the most common. The procedure involves placing the tip of a needle in the exact location of the abnormality by using mammography to show the needles' position. If this is not technically feasible, ultrasound or CT guidance can aid in placing the needles. When the needle is in place, a wire with a hooked end is threaded to the end of the needle and the needle is withdrawn over the wire, leaving the wire in place. An incision is then made by the physician doing the biopsy and the tissue around the wire is removed. The excised tissue with the wire tip in place is then x-rayed to confirm the presence of the abnormality (microcalcifications) in the removed specimen. If cancer is detected in this biopsy, further surgery is typically performed to remove the entire tumor and an area of normal tissue around it.
Advantages of an excisional biopsy include:
- complete knowledge of histology prior to planning further surgical treatment should cancer be found
- avoidance of false negative biopsies due to a sampling error (possible when pieces of tissue are biopsied with other modalities such as fine needle aspirations)
- If cancer is found and the specimen margins are negative for tumor, the biopsy may serve as the definitive lumpectomy
- the need for an incision and scar
- discomfort, anxiety
- increased health care costs
For an increase in number of clustered microcalcifications on serial mammograms, particularly when no mass is palpable, a needle localization biopsy is an indicated procedure. You should discuss all the specifics of your case with your oncologist.
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