Fine Needle Biopsy Accurate with Trained Doctors

August 24, 2001
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Thoroughly training doctors to perform fine needle biopsies dramatically increases diagnostic accuracy, UCSF researchers have reported. Fine needle aspiration biopsy (FNAB), once performed extensively in doctors' offices to identify breast and other cancers, has been falling from favor for years as the medical community's confidence in its accuracy has declined. It has been replaced in many cases with more invasive procedures that carry additional risk for patients, said the study's lead author Dr. Britt-Marie Ljung.

The UCSF study published in the August 25 issue of Cancer Cytopathology found that during 1992, 25 percent of breast cancers were missed at three San Francisco hospitals because poor sampling technique resulted in inaccurate biopsies. "Fine needle biopsy is a great technique when performed correctly," said Ljung, "and it can really help patients. It's fast, it's inexpensive, and it's less likely to cause side effects like bleeding or discomfort because the needle is so small." Ljung is professor of Clinical Pathology at the UCSF Helen Diller Family Comprehensive Cancer Center.

In FNAB, physicians use a fine gauge needle to remove samples of suspicious tissue that are evaluated microscopically. In the study group, formally trained physicians missed 2 percent of cancers, whereas physicians without formal training missed 25 percent. The formally trained physicians had completed fellowship training in cytopathology or the equivalent, and they had performed at least 150 FNABs under supervision. To determine that a cancer was missed, the researchers closely followed the medical histories of 927 women at three San Francisco hospitals for a minimum of two years.

Researchers used 1,043 tissue samples, patient records and the Northern California Cancer Registry database, which is estimated to contain 98 percent of all breast carcinomas diagnosed in the seven Bay Area counties. According to the study, the crux of the issue was the integrity of the biopsied tissue sample. Less-well-trained practitioners were more likely to send to the lab samples that contained the wrong cells. Cancer was considered "missed" either if a sample was misdiagnosed as benign, or if the sample was inadequate to reach a diagnosis. "The difference was entirely due to errors in sampling the lesion rather than in interpreting the specimen," the study authors said.

Patient charts indicated the location of a tumor within a patient's breast, allowing researchers to correlate the tumor to the earlier biopsy. "The only factor that made a difference in the rate of accurate diagnosis was the training of the practitioner," said Ljung.

Although the study only examined breast biopsies, the findings have broader implications, since FNAB can be used for any organ, she said. Many physicians who have observed low rates of accuracy in FNAB have turned to other methods. But when FNAB is replaced by surgical or core biopsy, costs rise, patients can endure delays and the risk of complications increases, according to Ljung.

"One solution to the problem of substandard FNAB results is to train a number of physicians well enough so that they can achieve a reliable diagnosis. We suggest that FNAB be concentrated in well-trained hands to provide the benefit of high-quality, rapid, minimally invasive diagnosis to the maximal number of patients," said the authors. The hospitals included in the study were California Pacific Medical Center, UCSF Mount Zion and UCSF Medical Center at Parnassus. The research was supported by a grant from the Department of Defense to the Carol Franc Buck Breast Care Center. The Breast Care Center is part of the UCSF Helen Diller Family Comprehensive Cancer Center, an interdisciplinary initiative that combines basic cancer science, clinical research, epidemiology/cancer control, and patient care programs throughout the UCSF campus.

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