Accuracy Rates of FNA for Breast Cytology Said to Be Increasing

PHILADELPHIA—Fine needle aspiration (FNA) for breast cytology has a false-positive incidence “very close to zero,” Nadia Al-Kaisi, MD, said in an interview with Oncology News International. “For the past several years,” she said, “the accuracy has increased because of increased recognition of the cytologic features of the various benign and malignant lesions.”

Dr. Al-Kaisi, associate professor of pathology, Case Western Reserve University, reported on the subject at the annual fall meeting of the American Society of Clinical Pathologists and College of American Pathologists. In the interview, she named four “new aspects” of FNA breast cytology: Improved accuracy, establishment of FNA clinics, increasing use of new processing techniques, and use of FNA in the diagnosis of nonpalpable lesions.

The Value of Experience

The incidence of false-positive FNA results is probably less than 0.5%, she said, adding that the incidence of false-negative findings is also decreasing, leading to improved sensitivity and negative predictive value. Nonetheless, she added, for various reasons, there remains a large percentage of false negatives (about 10% to 15%).

“This is either because of the difficulty inherent in the lesions themselves or because of the inexperience of the aspirator,” she said, adding that published studies have shown the value of experience.

Sensitivity is also markedly increased if the pathologist personally performs the aspiration, allowing for rapid assessment. “With immediate access,” she said, “you can tell on the spot whether the smear is diagnostic, that is, whether you have adequate material. And if you do not, then you can go ahead and re-aspirate while the patient is still there.”

Dr. Al-Kaisi mentioned the trend toward establishing FNA clinics where the cytopathologist aspirates the lesion, prepares the smear, and provides the diagnosis to the referring physician. “This is a trend providing convenience. I think more cytopathologists are establishing FNA clinics,” she said.

She noted that new preparation techniques and methodologies such as ThinPrep instruments are increasingly being used to process FNA samples, leading to increased accuracy.

Use in Nonpalpable Lesions

Finally, she said, FNA is beginning to be used more in the diagnosis of non-palpable lesions. “Now that more women are getting an annual mammogram, we’re discovering more mammographic abnormalities that need to be either followed or biopsied,” she said.

Use of stereotaxically directed FNA technology can be an important adjunct to mammography, raising the specificity of mammographic findings and possibly avoiding the need for a core biopsy.

She concluded that FNA is a “valuable tool” in the evaluation of palpable breast lesions. Its role in palpable masses varies at different institutions, from a screening technique to a diagnostic tool for planning definitive surgery or preop-erative chemotherapy. Now, she said, several multicenter studies are underway to determine whether FNA should be standard procedure after discovery of a nonpalpable mammographic abnormality, rather than excisional biopsy.