Experts Explain Intricacies of Image-Directed Breast Core Biopsies

The selection process for determining which procedure to utilize for an image-directed core breast biopsy often remains a mystery to those outside of the pathology and radiology world.

As a result of this ambiguity, Siziopikou and Sarah M. Friedewald, MD, assistant professor of radiology at Northwestern University Feinberg School of Medicine, came together at the meeting to present a joint discussion on the decision-making process faced by pathologists and radiologists in breast cancer biopsy.

The first half of the presentation was dominated by the use of core needle biopsies in diagnosing breast cancer. “Core needle biopsies have evolved into the optimal biopsy,” said Friedewald. “We have fewer complications with core needle compared to open surgical biopsy, with less than 1% of patients experiencing complications.” Siziopikou later added that in her pathology work she now rarely sees an incisional biopsy.

However, Friedewald cautioned that overall core needle biopsies have the potential for false negatives. In an Irish study1of 2427 consecutive biopsies over a 5-year period, 85 resulted in a false negative, with the biopsy coming back benign but the excision finding a malignancy. Of the 3 core needle biopsies available—ultrasound, mammography guided (stereotactic biopsies), and MRI—Friedewald advocated for the use of ultrasound whenever possible because of its greater chance of accuracy.

In the Irish study, ultrasound had the lowest rate of false negatives, and the lowest underestimation rates, 1.7% and 3.4%, respectively. Ultrasound also is more comfortable for the patient, said Friedewald, thereby increasing compliance, and there’s no radiation necessary as with stereotactic.

When calcification is present in the breast, Friedewald said stereotactic core needle biopsy is the first recommendation. While the suspected tissue can be easily targeted with this method, Friedewald remarked that patients might find the table used for the procedure quite uncomfortable. “Women with back and shoulder problems really struggle with this,” she said.

If the suspected calcification is too close to the breastbone, stereotactic biopsy can’t be used. For the procedure, a woman’s chest is pressed down into the device, with her breast placed through a hole beside which the biopsy needle is to be inserted. If the calcification is too close to the table, the tissue can’t be reached. This would be one case where the patient would need to undergo an incisional biopsy, said Friedewald.

Friedewald said MRI-guided core needle biopsy is considered a last resort, when the abnormality is only visible on an MRI. The procedure is often uncomfortable for patients and the 5-minute window available before the contrast dissolves limits the radiologist, explained Friedewald.

Fine needle aspirations (FNA) are a common biopsy seen by pathologists, said Siziopikou. For these, she said, the pathologist evaluates both the cells themselves as well as the background. “If a surgeon excises a section, we correlate the tumor to the x-ray and where it is on the body so we can determine our analysis.” Other common biopsies include core biopsies, excisional (after lumpectomy), mammography, and lymph nodes, said Siziopikou.

Because the breast has no shape, six different colors of ink are used to highlight the biopsied specimen, explained Siziopikou. The ink helps determine how far from the edge the specimen sits. “If it goes all the way to the edge, we will have to tell the surgeon, unfortunately, that we have a positive margin.” To further dissect biopsied tissue, it is converted into a solid block using paraffin wax.

Radiologists and pathologists have continual conversations about the condition of the patient, said Siziopikou. “This helps because we want to have an almost perfect correlation between what we are evaluating and patient care.”

Friedewald presented several real world case studies of patients with breast cancer, complete with visual images and related biopsies, to further explain the level of collaboration between radiologists and pathologists.

Siziopikou and Friedewald also explained the issues surrounding a DCIS diagnosis. Once considered rare, DCIS has become a very common diagnosis, noted Siziopikou, making up 19% of all new breast cancer diagnoses today. “Of interest is in autopsies studied, not related to cancer deaths, DCIS goes all the way to 15% of the cases, without ever having caused the deceased patient any problems,” explained Siziopikou.

What’s worrisome, she added, is that DCIS has the same molecular subclasses as invasive carcinoma, with a markedly increased risk of cancer—approximately 8% to 10% over baseline. It’s the work of radiologists and pathologists to clearly identify women with DCIS to their cancer care team, said Siziopikou, because oftentimes it requires immediate treatment.

Pathologist and radiologists must also contend with the increased role of genetic testing, and not limit their focus onBRAC1andBRAC2mutations, said Siziopikou. “The vast majority of patients have one or more low risk factors that intersect with each other and somehow drive their risk of cancer,” she clarified. A patient’s ethnic background, which may also correlate to less well known genetic mutations, should always be taken into account by the cancer care team, said Siziopikou. “That way we can screen for those genes.”

In short, the best explanation of what goes on behind those laboratory doors: “The radiologist and pathologist are working together in order to optimize patient care in image-guided tissue sampling,” said Siziopikou.

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