Biopsy Best to Confirm Breast Cancer Diagnosis
A breast biopsy is the preferred follow-up procedure to confirm a cancer diagnosis, even though several other test options exist and may be offered by physicians, according to a report from the Agency for Healthcare Research and Quality (AHRQ).
The AHRQ study compared the effectiveness of biopsy, long considered the "gold standard," with four other tests.
The other four tests were magnetic resonance imaging, or MRI; ultrasonography; positron emission tomography (PET) scanning; and scintimammography, or breast scan.
The report focuses on a very specific question, says AHRQ Director Dr. Carolyn M. Clancy. The researchers were addressing whether or not any of the other noninvasive tests sufficiently are accurate to diagnosis cancer or to rule it out.
A biopsy is accurate but invasive, requiring the taking of a sample of breast tissue and analyzing it for signs of cancer in a lab. Because of this, researchers have been searching for noninvasive tests that would be as accurate.
The four tests assessed in the report, all suggested as substitutes for biopsies, were not as accurate as a biopsy overall.
The tests studied missed between 4 percent and 9 percent of breast malignancies in women at average risk, the report found, and probably would miss more cases than that among women at higher risk of the disease.
How accurate is accurate enough?
"Some experts say a test would have to miss fewer than 2 percent to be considered sufficiently accurate," says Dr. Clancy.
It is hard to pinpoint the exact accuracy of biopsies, but a study published last year in the Annals of Surgery found that the "false-negative" rate for one type of biopsy, called a "core biopsy," was 6 percent, according to Fran Visco, the first president and spokeswoman for the National Breast Cancer Coalition in Washington, D.C.
In the AHRQ report, the researchers found that the use of MRI missed 38 cancers for every 1,000 women; ultrasound missed 50 tumors for every 1,000 women; and PET scans missed 76 per 1,000 women.
Scintimammography, a nuclear medicine test method that uses a small amount of a radioactive substance and a scanner to detect cancer, missed 93 tumors for every 1,000 women.
The report on the four noninvasive tests is valuable, explains Visco.
"My interest in the 2006 AHRQ report focuses on the fact that we move these technologies into clinical practice when we don't have the data that show they are effective,” notes Visco. “That adds to healthcare costs and also doesn't serve women well."
Having access to solid data that proves a test is accurate will help women and the healthcare system, she says.
Dr. Clancy adds that the findings in this study provide good information for women to have additional conversations with their physicians.
If a physician suggests one of the alternate tests after an abnormal mammogram it would be reasonable to ask for a biopsy instead of these tests.
Always consult your physician for more information.
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Based on initial breast exams, your physician may decide that no further tests are needed and no treatment is necessary. In such cases, your physician may want to check you regularly to watch for any changes.
Often, however, the physician must remove fluid or tissue from the breast to be sent to the lab to look for cancer cells.
The procedure, called a biopsy, may be performed using a needle to acquire a tissue sample or by a surgical method.
A biopsy is a procedure performed to remove tissue or cells from the body for examination under a microscope. A breast biopsy is a procedure in which samples of breast tissue are removed with a special biopsy needle or during surgery to determine if cancer or other abnormal cells are present.
Biopsies may be performed under local or general anesthesia. There are several types of breast biopsy procedures. The type of biopsy performed will depend upon the location and size of the breast lump or abnormality.
Types of breast biopsy procedures include, but are not limited to, the following:
fine needle aspiration biopsy - a very thin needle is placed into the lump or suspicious area to remove a small sample of fluid and/or tissue. No incision is necessary. A fine needle aspiration biopsy may be performed to help to differentiate a cyst from a lump.
core needle biopsy - a large needle is guided into a lump or suspicious area to remove a small cylinder of tissue (also called a core). No incision is necessary.
surgical biopsy (also called an open biopsy) - a surgeon removes part or all of a lump or suspicious area through an incision into the breast. There are two types of surgical biopsies. During an incision biopsy, a small part of the lump is removed; whereas during an excisional biopsy, the entire lump is removed.
In some cases, if the breast lump is very small and deep and is difficult to locate, the wire localization technique may be used during surgery. With this technique, a special wire is placed into the lump under x-ray guidance. The surgeon follows this wire to help locate the breast lump.
There are special instruments and techniques that may be used to guide the needles and to assist with biopsy procedures. These include, but are not limited to, the following:
stereotactic biopsy - stereotactic biopsy finds the exact location of a breast lump or suspicious area by using a computer and mammogram results to create a three-dimensional (3D) picture of the breast. A sample of tissue is removed with a needle.
Mammotome® breast biopsy system (also called vacuum-assisted biopsy) - a type of tube is inserted into the breast lump or mass. The breast tissue is gently suctioned into the tube, and a rotating knife removes the tissue.
ultrasound-guided biopsy - a technique that uses a computer and a transducer that sends out ultrasonic sounds waves to create images of the breast lump or mass. This technique helps to guide the needle biopsy.
advanced breast biopsy instrumentation (ABBI) - uses a rotating knife and cylinder to remove a large sample of tissue. Although this type of procedure has not received widespread acceptance, it is often possible to remove the entire breast lesion with this method.
sentinel node biopsy - a procedure used to determine if cancer cells have spread to the lymph nodes. It involves injecting a dye and/or radioactive substance near the tumor.
Always consult your physician for more information.
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